Notes from soggy bottom

Hooded Crane Origins

2011-12-29T13:45:00.000-08:00

Where did the Tennessee Hooded Crane come from?

Apparently this is much on the minds of the North American birding community. Through yesterday there had been 922 visitor-days tallied on the sign-in sheet at the observation platform at Hiwassee NWR since the crane first arrived in mid-December; these visitors have come from 38 states and several foreign countries. My wife and I stopped by on our way to Atlanta a few days ago and were rewarded with leisurely views of our state's current celebrity V.I.B. Opinions vary quite a bit as to what the source of this bird might be; one youtube video appears to suggest that he or she came from Planet Claire.

My initial knee-jerk reaction on hearing of the bird was "that's gotta be an escapee." But as I have learned more, I have shifted from this starting point. There are two critical questions:

1. Is it there a reasonable scenario under which a wild Hooded Crane would arrive in Tennessee without human assistance?

2. Is there a plausible source for an escapee?

My feeling is that if the answer to (1) is yes and (2) is no, then my vote for the bird (I am on the Tennessee Bird Records Committee) is "accept;" otherwise it is "reject." I am still very much in exploratory, open-minded mode about this. But here are some of the most interesting things I have come across:

Much was made of the escape of three Hooded Cranes in Idaho a few years back (date appears to be uncertain). However, it seems fairly certain now that these birds were pinioned and thus could not be the source of either the Tennessee or Nebraska birds in 2011.

The total zoo population of Hooded Cranes worldwide is very small (I have seen the number given as 84), and no escapes are known. The number and status of birds in private collections I have not seen so much about, but there are not going to be many. As I saw it described, "The Hooded Crane is a rare and valuable species and usually in a very secure setting." This means banded and probably pinioned.

There have been long-distance vagrant Hooded Cranes seen in Asia. There are records from Kazakhstan and eastern India, both at least 1000 miles from the usual breeding and wintering areas. If you go only slightly farther to the northeast rather than west, you are in mainland Alaska, and certainly in potential contact with U.S.-wintering Sandhill Cranes.

John Vanderpoel, in a recent blog post, describes the movements of a family group consisting of a Sandhill Crane, a Common Crane, and hybrid offspring. He says that they were Siberian nesters that were seen in the Jasper/Pulaski refuge in Indiana, the Yukon Delta (headed west), and Nebraska. If he has the facts correct, this would seem to make the "wild Hooded Crane comes to Tennessee" scenario very plausible. Many people have doubted whether a wild Hooded Crane could make contact with the Sandhills that winter in Tennessee. Considering that many of the Hiwassee cranes also pass through Jasper/Pulaski, it's only a couple of small steps from the travels of this wild CommonHill Crane family to plop a wild Hooded Crane at Hiwassee (and Nebraska last spring). Remember that this is not a Sandhill Crane and it will not necessarily be tied to the traditional migratory patterns of the Sandhills. It is also an unmated bird, which has a long summer to wander solo in the north.

In recent years there have been Common, Hooded, and Demoiselle Cranes found in the U.S. in the company of flocks of migratory Sandhill Cranes. If these are all escapes, why are they all species that nest in central and eastern Asia, with none of the African or Australian species (some of which are also common in captivity)?

As I said, I remain in investigative mode and am a good ways from casting a BRC vote, both intellectually and temporally. The evidence at this point is definitely trending towards "wild" in my mind; but that could change. Additional information, especially about captives, would be extremely welcome.

ADDENDUM

I've been looking in to the Common Crane scenario more, and here is what I have found in back issues of North American Birds (it is more complicated than what Vanderpoel wrote). If anyone has corrections or expansions to this info, by all means let me know:

Fall 1998: Alaska's first Common Crane in 40 years is found in Delta Junction in a (Lesser) Sandhill staging area. This is southeastern Interior AK, far from the Yukon Delta or Siberia.

Spring 1999: Common Crane at Kearney Nebraska invites speculation because it "shared the pale plumage worn by [the] bird found last fall in Delta Junction." Bird in the company of Sandhills, mostly arctic-nesting Lessers.

Fall 1999: Common Crane mania in Quebec. One adult associating with a Sandhill and two juveniles of possibly hybrid characters. Meanwhile elsewhere in the province, two 1-year old Common/Sandhill hybrids found. This is Greater Sandhill territory, though the subspecies of the Sandhill mate was not determined. Speculation that the adult might be the same bird seen several years previous on the Atlantic coast of the U.S. and determined to be an escapee of known origin, along with two years' worth of its hybrid offspring. No connection presumed between this bird and any wild birds from western North America. Later, though, this escapee was found to be happily resident and reproducing in New Jersey and not wandering in Quebec (see below, Winter 2000-2001)

Fall 1999: About a month later, a Common Crane appears at Jasper-Pulaski in Indiana, the major staging ground for Greater Sandhills. The bird is in the company of an adult Sandhill and two juvenile hybrids. Initially believed to be the same as the Quebec bird, but then the adult Sandhill was determined to be a LESSER Sandhill. Suspicion then turns towards its possibly being the same bird seen in Nebraska in the spring. Birders farther south eagerly await the arrival of the Common Crane with the migrating Sandhills; however it is not seen.

Spring 2000: A Common Crane appears in Nebraska in the company of a Lesser Sandhill Crane and two apparent hybrid youngsters. Could the Indiana family have found its way back to Nebraska???

Winter 2000-2001: An SA report in the Hudson-Delaware region details that there is a small resident population of Sandhills, the original escapee Common Crane, and numerous hybrid offspring in New Jersey. So this escaped bird does not account for the Quebec or Indiana birds.

Of course it is not definite that ANY of these birds were the same individual, or than ANY of the eastern birds were wild (western birds are generally presumed wild). One thing it does make clear, though, is that some Lesser Sandhills do reach Jasper-Pulaski. The similarity to the sequence of the three recent Hooded Crane occurrences (ID spring 2010, NE spring 2011, TN fall 2011) is interesting. It does appear to suggest that a wild Common Crane made it over from Siberia, paired up with a Lesser Sandhill, and travelled to Indiana (and presumably farther south, as it disappeared from Indiana in November).

Hooded Crane in Tennessee

2011-12-14T19:53:00.000-08:00

I'm sure this news is buzzing through the birdosphere already!

An adult Hooded Crane was found today among the wintering Sandhill Cranes at Hiwassee National Wildlife Refuge in east Tennessee. For those unfamiliar with the species, this is a bird of southeastern Siberia and elsewhere in the far east. It is endangered in the wild, and also kept in captivity in North America. Amazingly, this is the THIRD Hooded Crane sighting in the U.S. in recent years, after one in Idaho in 2010 and one in Nebraska in April of this year. Discussion will doubtless continue for a long time about the possibilities for wild versus escaped origin, the odds that the Tennessee bird could be the same as the Nebraska and/or Idaho birds, etc. But whatever its origins, this is a rare and beautiful sight, bringing the total of crane species currently residing at Hiwassee to three (though only one is presently ABA-countable).

Woodpecker Wingbeats Revisited

2011-11-14T21:51:00.000-08:00

I didn't really want to dredge all this old stuff out again, but it has remained a point of contention and misaprehension, and of course there are some new datums to consider.

Years ago I posted a graph of some comparative wingbeat data between the bird in the Luneau video and some known Pileateds, without comment. Well, it seems time to repost this with additional data, and with comment. I have added the two launch sequences of the Imperial Woodpecker, and the data presented by Louis Bevier for his best (fastest, most Luneau-like) Pileated (click image for a larger view):

First some comments on the Bevier data (for those curious my original response to his articles is here). These have only been presented in very limited, summary form without the actual videos being made available. I realize that he is operating on the notion that he only needs to find one Black Swan (to refute the statement that All Swans Are White), and feels that there was no need to lay out extensive results. But the swan in question was described in a somewhat roundabout way, and on closer inspection it kinda begins to look sort of whitish, really. The main point of fogginess is the way he expressed the wingbeat frequency data, which initially suggested that the flap rate of this champion flapper Pileated only dropped from 8.8 Hz to 7.5 Hz over 12 wingbeat cycles. But the numbers he gave were cumulative through 12 cycles, not the individual value for the 12th cycle. Reworked from the data points given, you get what I have plotted, showing averaged of 8.8 Hz for cycles 1-5, 7.4 Hz for cycles 6-9, and 6 Hz for cycles 10-12, which is a much more substantial dropoff than suggested by the data as originally presented. One also has to wonder at the comparison between captive birds being released from human hands versus a free-flying bird launching from a tree; both the starting dynamics and the bird's likely mental state would seem to be very different between the two. Jumping (dropping? being tossed?) from human hands is a pretty strange way for a woodpecker to initiate flight; on the other hand, flushing from a tree trunk in response to the approach of a couple of guys in a jon boat propelled by an electric trolling motor is a rather ordinary experience for a woodpecker in the Big Woods, I'd expect, and not likely to trigger extreme behaviors.

Next, some general comments about the graph. Like the earlier graph, it shows the Luneau bird holding steady and flapping the fastest of them all, with very little upward curve to its line (upward= slower wingbeats). The Pileateds start out near it, but tail off after several wingbeats. Even the Bevier bird does not in fact keep up (in contrast to the assertions at the original site), falling increasingly behind just like all the others. The Imperial lines bracket the Pileated data for the most part, but the salient feature here is that it also does not tail off (slow down), remaining steady and straight.

I have maintained all along that wingbeat rate per se is not an especially strong or informative piece of evidence, as it is just one tidbit of data about flight dynamics and many things can affect it. What I find more informative are the mechanics underlying these changes (or lack of changes) in wingbeat rate. There is a qualitative feature of Pileated flight that causes this tailing off in wingbeat rate. After around 3-7 wingbeats, all the launching Pileateds I have seen videos of begin inserting brief closed-wing pauses in the upstroke between flaps. Initially these pauses are too brief to be obvious to the naked eye, but they are clearly evident on slow-motion video. As the flight proceeds the pauses grow into visible bounds (closed wing ballistic flight segments) separated by discrete flaps, which we all know as the classic Pileated cruising flight. It is the insertion of these discrete pauses that causes the apparent slowing of the wingbeat rate, not a dramatic reduction in the rate at which the wings are being moved during the flap. Again, all Pileated videos I have seen show this. I would expect the Bevier bird shows this too given its rapidly dropping flap frequency.

The Luneau bird does not display this flight behavior, which is why its flap rate holds steady. The Imperial does not display it either, with steady flaps until it either leaves the frame or closes up into one, discrete, readily visible bound. At the end of the one bounding segment that is shown until its end, the Imperial then resumes unbroken rapid flapping without pauses. It is worthy of note that in the Luneau video, as the bird reappears between trees in the later segments, it is always showing steady wingbeats, even at the very end. No closed wing bounds or pauses are discernible, though admittedly it gets hard to judge. This presence or absence of these brief upstroke pauses is a discrete qualitative difference between the flight styles of these birds, not a mere quantitative variation. It is a much "harder" distinction than the smallish differences in flap rates. I suspect that if this discussion were about virtually any other species of bird (even continental hyper-rarities), this type of feature would be readily promoted and accepted as a diagnostic character for resolving identification questions.

Summary: The flight of the Luneau bird is inconsistent with what appears to be the characteristic, even diagnostic, flight style shown by every Pileated video I have found. It is somewhat faster, but otherwise consistent, with the flight of the Imperial Woodpecker (in the one film that exists). Louis Bevier's "black swan" fast-flapping Pileated appears to be in front of a metaphorical and rhetorical bright light that makes it appear black; its actual color cannot be judged from the information available.

The Imperial Film

2011-11-04T07:19:00.000-07:00

Note: Those who did not come here via Cyberthrush's blog might be interested in the debate between me and David Sibley on these matters in the comment section of this post.

Also note: My subsequent post elaborates more on the wingbeat rate and flight dynamics issues.

As should be widely known by now, the legendary film of a female Imperial Woodpecker shot in Mexico in the 1950s has finally been published and is available for all to see. Contrary to the conspiracy theories advances by Scott Crocker and others, this film does not in fact undermine the claim that the infamous video shot by David Luneau in Arkansas in 2004 is an Ivory-billed Woodpecker. In fact, even on first viewing, it would appear to support the Luneau et al Ivorybill claim.

The Lammertink et al paper covers the film itself, its history, and the present-day circumstances at the spot where it was filmed; I will not delve in to that here. Please read the article and view the video at the site I linked above if you have not already done so. My focus here will be on the impact this film has on analysis of the Luneau video, as it fills a major data gap that seriously impeded that analysis until now: the lack of any films of Ivory-billed Woodpeckers in flight for comparison. Of course, the Imperial Woodpecker is not the same species as our North American Ivorybill, but it is very closely related. I don't have the reference at hand, but wasn't there a recent genetic study that found that the genetic distance between the Imperial and the North American Ivorybill was about the same size as the distance between the Cuban and North Amercian Ivorybill subspecies? I believe it is fair and justifiable to use the Imperial as a close analog to what our Ivorybill would have looked like on film.

For the record, I had no advance access to this film. I saw it for the first time on the day of publication last month, same as everyone else. So I have not had months or years to examine it, nor were any of my earlier conclusions about the Luneau video influenced by having viewed the Imperial film, having spoken to anyone who had viewed it, or even having heard any credible rumors as to what it contained.

All of my previous analyses of the Luneau video can be reached from this link which is the same as the one in the right-hand sidebar on this blog. I will take this work as read and will not repeat it in detail, simply refering to my important conclusions and findings. Anyone who read my work could tell that I had very strong leanings towards an Ivorybill identification for this bird, and found multiple major and fatal flaws in the Sibley et al analyses that concluded that this video was consistent with a poorly-imaged Pileated Woodpecker. However, the lack of any suitable Ivorybill comparison material left unresolved dangling issues in several areas that have stopped me from proclaiming that this bird was definitively an Ivorybill. These issues fell into two areas: the launch sequence, and the flight mechanics (structure and pattern of wingbeats).

Launch behavior

First, to the launch sequence. This focuses on Infamous Frame 33 of the Luneau video, when a flash of white appears from behind a tree trunk just as the bird launches in to flight. The Cornell interpretation has been that this is the white shield on the back of the bird, and they used this to estimate the size of the bird. Sibley et al felt this flash showed the underside of a raised wing, and my own examinations of launch sequences of Pileated Woodpeckers led me to agree with this alternative interpretation. However, in contrast to Sibley et al, I found that the subsequent frame strongly suggested that the trailing edge of this underwing was white, not black, and that all the supposed black trailing edges they identified in the entire video were nothing but edge artifacts created by the digital imaging process. Hence even this alternative interpretation pointed to Ivorybill, not Pileated.

Now having seen the Imperial film, I have to say I may have been mistaken in disagreeing with Cornell's interpretation of this sequence. The behavior shown by the Imperial in the two launch sequences in the film is a very good match for the Cornell hypothesis and very different from that shown by typical Pileateds. Of course, as I mentioned before, both interpretations (when you stop misinterpreting imaging artifacts as plumage) come down on the Ivorybill side of the scale; but the Cornell interpretation is much stronger in both providing an unambiguous view of the "white shield" and in giving a size estimate that is outside of the Pileated range and right on for an Ivorybill. So this is a much heavier brick in the Ivorybill tray.

Flight mechanics: Flap rate

Discussions of the flap rate of the bird in the Luneau video generated a great deal of controversy. Its wingbeat frequency was higher than that shown in any of the Pileated Woodpecker comparison material available; in spite of claims of unpublished videos showing otherwise, there has still not been a video of a Pileated Woodpecker presented to the public in which the bird achieves and sustains such a rapid wingbeat rate. Of course, the real problem was that there was no film of an Ivorybill in flight to indicate whether or not this species actually possessed a rapid and sustained flap rate. Sibley and others argued that as a larger species, it should be expected to show a slower flap rate.

The Imperial isn't an Ivorybill, but it is very closely related and even larger. As discussed by Lammertink et al, it shows a very fast flap rate, considerably faster than what is typical for a Pileated. In the first 5 wingbeats of the second flight sequence, it achieves 8 flaps/second, nearly matching the Luneau bird.

I think we can safely conclude now that the Ivorybill had a fast, sustained flap rate, significantly faster than that of the Pileated, and likely extremely close to what the Luneau bird shows.

Flight mechanics: Wingbeat patterns

The flight of a Pileated Woodpecker after launch typically consists of a short series (3 to 7) of fairly rapid wingbeats, then a break into bounding flight where individual or paired wingbeats are separated by bounds (periods when the wings are folded in to the body and the bird functions as a ballistic missile). Sustained cruising flight of a Pileated generally continues this pattern of discrete flaps separated by bounds: flap....flap,flap....flap....flap....flap...

The flight of the Imperial contrasts sharply with this. In the first flight sequence the bird executes 7 wingbeats without a break before it moves out of sight. In the second it completes 15 steady wingbeats then executes a bound. After the bound, it resumes steady flight with 5 more uninterrupted flaps before it disappears from view. In the final sequence, the launch is not visible. When the bird appears in frame it is in steady flight, and completes at least 12 wingbeats before closing up into a bound and "cannon-balling" until the end of the film. One could describe the flight of this bird more as "flapapapapapapapapapapapapap.....flapflapflapflapflap"

The Luneau bird is in view for 4 seconds from launch to its final diappearance. It passes behind trees intermittently during this time. It is in continuous view shortly after launch for about 1.2 seconds, during which it completes 10 uninterrupted flaps without a hint of bounding flight. For the rest of the video, every time it reappears between the trees it appears to be engaged in steady wingbeats without bounds. There is no point at which the wingbeats appear to have stopped or even be separated by brief bounds. The bird completes 23 visible wingbeats during these 4 seconds; if you watch in slow motion and count along with the rhythm there seem to be no breaks, and interpolating behind the trees yields about 27 flaps in this time. This is a far better match for the Imperial than for a Pileated.

Flight mechanics: Wing movements

The film is shot at 24 frames per second (fps) which means that there are only a few frames (typically 3-4) representing each wingbeat. Hence, in any given wingbeat there are only a few wing postures shown. However, each flight sequence shows multiple wingbeats, and the adjacent flaps are often viewed from a similar angle and occur at about the same rate. However, as the flaps and camera shutter are never in perfect synch, each successive wingbeat is imaged at different point in the flap cycle. So, one can composite several adjacent wingbeats to create an approximate representation of what a single wingbeat would have looked like had it been shot at a higher frame rate. This is similar to the manner in which films of rotating objects (vehicle tires, fans, etc.) often will appear to show the object spinning in slow motion, or in reverse. I have constructed these composite wingbeats for two of the three flight sequences in the Imperial film, with interesting results. The second sequence yields the most attractive result, whith three successive flaps combined in to one:

Note that the bird jumps around in the frame, and the background does all sorts of distracting things. But if you concentrate on the bird, this yields what looks like a pretty fair representation of a singe flap filmed at 72 fps (by a very shaky hand).

The third flight sequence yields an interesting composite (again three separate flaps combined for a simulated frame rate of 72 fps):

In this case we see the bird almost directly from behind.

The first flap sequence does not yield a good composite. The bird traveled far across the frame, and the flaps were almost in synch with the shutter so there is less of an effect of each frame filling in the gaps from the others to create a smooth wing motion. And for purposes of comparison with the Luneau video, this side-on viewing angle is perhaps the least informative of the three.

Note that both of these composite sequences show the bird in cruising flight, not during the initial takeoff and acceleration. The salient feature notable here is the relatively shallow nature of the wingbeats compared to Pileated flight. The wings are not fully opened on the downstroke until they are at about a 45 degree angle, and they are draw in rapidly at the bottom of the stroke without being fully extended downwards. This is of course exactly what is shown by the Luneau bird and is not typical of Pileated flight.

Flight mechanics: Bowed wings

One of the salient features I found in the Luneau video that was inconsistent with Pileated flight was the manner in which the bird bows its wings downward during the downstroke. This is not apparent in the two composite sequences of the Imperial flight shown above. However, it does appear earlier in the Imperial flight sequences, most prominently in sequence 2 while the bird is accelerating and banking. A final composite shows the bird in mid-downstroke on 6 successive wingbeats:

The flap rate of the Imperial at this time was almost exactly 8/s, so the wings are imaged in nearly the exact same part of the cycle in each frame. Note that the bow increases as the bird banks, then flattens out when cruising flight is achieved. The wing bowing never looks as prominent as is shown by the Luneau bird, but it is present nonetheless. It also appears to be present in the side views of the first Imperial launch sequence in frames 654, 658, and 663. It does not show at all in the third flight sequence, which is missing the initial acceleration and also shows the slowest flap rate of the three.

The naked eye view

The frame-by-frame analyses are revealing about the behavor of the bird, but they do not necessarily reflect directly on what a birder in the field sees when a large black and white woodpecker flies off a tree and vanishes in to the forest. To give a suggestion of what this might all look like to the naked eye, I created a mash-up of 5 segments of fleeing large woodpeckers. I used the first two Imperial flight sequences, the Luneau Video, and two of David Nolin's Pileated videos. For the Pileateds I deliberately chose the two most Luneau-like of them, showing a bird executing rapid flaps and sustaining steady flight for the longest time before breaking in to bounding flight. The modern digital videos are deinterlaced at 30 fps (alternate deinterlaced frames); the Imperial film has been adjusted from 24 to 30 fps by duplicating every 4th frame (standard film-to-video conversion procedure). You likely will need to play this video repeatedly to take it in and start to get a sense of the comparisons between the birds. The mash-up is not intended to show detailed wing movements, etc; it is deliberately shrunken so you just get the quick flash impression, as though you were startled in the woods by stumbling upon one of these birds.

First to the marked similarities. All the birds explode from the tree in a barrage of rapidly flashing black-and-white. The differences in flap rate are not really discernible initially. And all take off like a chiropteran out of Hades. The Pileateds' breaks from steady flight to rapid bounding flight are noticeable at the end of their sequences on repeat viewing, but it is not a dramatic shift. Remember that I deliberately chose the two most Luneau-like (and also Campephilus-like) videos I had on hand for this comparison. The real contrasts to the naked eye would probably happen later in the sequence, when the slow bounding flaps of a Pileated would contrast sharply with the sustained rapid flaps of a big Campephilus (perhaps broken by well-defined bounds); but lacking a longer Imperial movie this is not knowable for certain. Overall I would say that in a place where a large Campephilus was known to occur alongside Pileated Woodpeckers, then a practiced eye could learn to distinguish the two species from a rapid naked-eye glimpse as they explode off trees and vanish into the forest based on flight gestault. Hopefully this situation will arise again somewhere in the future; at the present there is nowhere on earth that matches this description.

Conclusions

As I mentioned before, I have in the past generally hedged my declarations about the identity of the bird in the Luneau video, stopping just short of proclaiming what species the bird is rather than what I felt it was most likely to be. Enough of that.

The bird in the video shot by David Luneau in Arkansas in 2004 is an Ivory-billed Woodpecker, Campephilus principalis. I have no residual doubts, either personal or scientific. This species did not go extinct in 1945 or 1984, it persisted at least through 2004 and is quite likely still extant as I type these words. All the anomalies identified a priori (without foreknowledge of the Imperial film) in the flight of the Luneau bird that did not appear to line up with a Pileated Woodpecker do line up with the documented flight of an Imperial Woodpecker, the Ivorybill's closest relative. Combine this with the fact that there are no other discernable features of the bird that are inconsistent with the Ivorybill ID and several that do not match a Pileated (again, when you stop trying to make plumage markings out of image artifacts), and the case is closed.

I will echo what I said in some of my other Ivorybill posts. This creature is not a ghost, a fantasy, or a yeti. It is a bird. A very rare bird that is very difficult to locate and relocate. But it is a bird nonetheless, one that is probably alive and pecking on a tree somewhere within a few hundred kilometers of where I sit right now. Birders, ornithologists, and conservationists should treat it as such.

If any of these video links fail to function, please post a comment to let me know this so I can address the issue. I work over dialup so it is often hard for me to evaluate these things myself. Thanks!

Tennessee Breeding Bird Survey -- Summary

2011-10-11T13:49:00.000-07:00

For me, major point to be gotten from 45 years of the Breeding Bird Survey in Tennessee is that the birds are doing pretty well, overall. Most species have shown increases in their numbers, and the non-native invaders remain a small component of the avifauna in most areas. The two most coherent trends are large increases in diurnal birds of prey and in a large suite of forest-dwelling birds that do not winter primarily in the neotropical regions. The former I would expect to be attributable to direct conservation efforts and increased cultural awareness; the latter strongly suggests a fundamental and substantial improvement in the amount and quality of forest habitat within the state. Even beyond these suites of species, trends average modestly upwards in most cases (even for the neotropical migrants).

Behind this happy picture there is a small suite of species that appear to be in serious trouble. Landscape-level habitat changes probably underlie many of these large declines; the same improvement in forest habitat will be linked to a reduction in edge and agricultural habitats. The exact mechanisms underlying these declines are doubtless unique to each species and are not always obvious. Some of these drops seem more drastic than simple habitat changes can account for.

One lesson I would also take from these data is: "Conservation works." Many of these optimistic trends really took off in the late 1970s; it hardly seems coincidental that this comes on the heels of the major advances in environmental legislation and programs that began in ernest in the early 1970s. Of course this can make avian conservation a victim of its own success -- why do we need all these programs when the birds are doing so well? This same ironic conundrum affects all successful programs. It still does not mean that we should overlook or downplay the successes and try to gloss over the fact that in total our state's breeding bird populations appear substantally healthier than they were 45 years ago.

The final lesson would be: "Past performance is no guarantee of future results." Many of these upward trends show hints of abating in the last decade, though it is too early to tell for certain. This may just be the wobbles of this varied and nicely-rebounded avifauna as it settles down into a new quasi-steady state in our improved, avian-friendly landscape. But it might not. Nothing can be safely taken for granted in this arena.

As a closing note, I should point out that I do not see any suggestion of a climate change effect in these trends. There is no pattern of species spreading preferentially northwards, southwards, eastwards, or westwards, as would be expected in response to large-scale shifts in climate patterns. This is not surprising, as the actual climate change signature in Tennessee's own climate records remains very small and difficult to detect statistically if it is there at all. One would expect these effects to show earliest and strongest in species that nest in areas experiencing the greatest changes, such as the far north. We of course only see those birds in Tennessee in migration and in winter.

Whatever the future may hold, we in Tennessee have headed in to the Third Millenium with a breeding avifauna that is on the whole diverse, robust, and thriving. Let's work to keep it that way.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS: Inflection Points

2011-10-09T17:17:00.000-07:00

As I scrolled through all those graphs for the individual species, it became clear that 45 years was not only long only enough to show trends, it was long enough to show trends in trends -- the second derivative, not just the first. Few of the graphs show a simple up or down trend over the whole period, even when allowance is made for the year-to-year wiggles. American Goldfinch provides a stark example of this; Chipping Sparrow shows another. There appear to be three periods around which these inflection points cluster. I have had trouble making sense out of some of these; perhaps readers with more knowledge of the changes in land use, legislation, and other possible impacts in the mid-south during this era might shed some light.

Turning Number 1: Late 1970s-1980

Something clearly happened around this time. I discussed this earlier as the Great Sparrow Shift; it involves other species as well, from Goldfinches to Orioles to Herons. This is the time at which several of the woodpeckers and raptors began their impressive increases. Overall, for the species that seem to show a notable shift in the direction of their trend lines at this time, the large majority of these shifts are towards the positive. Many of these are weedy and edgy species, though a marked exception is the Gray Catbird, which began a sharp drop around 1980.

Turning Number 2: Around 1990

About a decade later, there was another shifting in the trend lines for a variety of species. This is a very mixed bag, with some increasing trends flattening while other flatlines started increasing and some species entirely changed directions. As with the first turning, the majority of the shifts were positive, but less dominantly so in this case. Wood Ducks, Chimney Swifts, Great Horned Owls, and Red-winged Blackbirds are among the species that began declines at about this time.

Turning Number 3: Early 2000s?

As it is close to the end of the current dataset, this third turning is less definite. Most of these suggested trends remain hard to distinguish from ordinary short-term wobbles. Still, there are indications of another shift in the trend lines for many species in the last decade. Unfortunately, most of these possible shifts appear to be in the wrong direction, or at least the flattening out of a long-term increase. There are some positives, including the surges in Tree Swallows and Mississippi Kites. The coming decade will tell whether most of these hinted-at changes are sustained.

I would expect these turnings to primarily be associated with landscape and habitat shifts. These could come about from official programs, economics, or many other factors. I would be curious to hear suggestions as to what these factors might have been.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Next: Summary

Tennessee BBS: It’s the Habitat

2011-10-09T11:49:00.000-07:00

As alluded to in the last post, the population trends of birds indicated by numbers from the Breeding Bird Survey in Tennessee appear to be related in some degree to the habitat requirements of each species. I looked at this in more detail by categorizing each species according to very general, landscape-level habitat preferences. The categories I chose were:

Forests -- relatively continuous and closed canopy forests. Occurs throughough the state, but most extensive in the eastern mountains and hill 'n' holler portions of the Highland Rim.

Edge/Mosaic -- the mosaic of woodlots, smaller farm and pasture areas, edges, roadsides, successional clearcuts, lower-density houses, and other mixed habitats typical of rural and less dense suburban areas that archetypally characterize much of Tennessee. Widespread statewide, and especially typical of the Highland Rim, hillier parts of the Coastal Plain and Central Basin, and the less rugged areas of eastern Tennessee.

Open country -- large-scale acriculture, with most land area in croplands and pasture. Characteristic of much of the Coastal Plain and Mississippi Alluvial Valley, the flatter inner Central Basin, and the Barrens areas of the Highland Rim. Small areas of this sort of landscape occur in most regions of the state wherever flatter ground occurs.

Residential/suburban/urban -- higher population density areas with lawns, “landscaping,” parks, commercial areas, etc. Includes centers of small towns as well as suburbs of large metro areas.

For each species, I checked off one or more of these categories based on general pereferences, not strict obligate requrements. For instance, Broad-winged Hawks are scored as “forest” and Horned Larks as “open,” but I have seen and heard both species from the exact same spots on our “edge/mosaic” farm in a Highland Rim hollow.

I also added a fifth category, both because it is of much interest in the conservation community and because a quick inspection seemed to confirm its significance. I checked off species that are neotropical migrants -- those migrants for which the majority of the population winters south of the U.S.

And as a final detail, when I calculated averages and other statistics on the percent changes, I used a logarithmic transformation in the form of X = ln(N_f/N_i) where N_i is the average count in the initial 10 years (1966-1975) and N_f is the average count in the final 10 years (2001-2010). This straightens out and balances the skewed nature of these ratios and gives them a more approximately normal (statistically speaking) distribution. Using the log metric, if one species has dropped to half while another has doubled, they will average out to zero. Using the straight percentages, they would average out to +25%. To give the final numbers, I converted these log transfomed averages back to regular percentages.

Averages by habitat type

When treated as described above, the following average and median changes come out for birds of each habitat preference:

Habitat	No. Species	Median	Mean
Forest	36	+74%	+101%
Edge/Mosaic	59	+35%,	+24%
Open	27	+15%	+32%
Residential	20	+67%	+71%

Though statistical tests do not make these trends significant, they confirm the impression that forest species are doing better than average. This gives a strong suggestion that one of the main driving factors for the rise in numbers of most Tennessee birds has been an improvement in the quantity and quality of forest habitat across the state.

The Neotropical Effect

When looked at in isolation, the difference between the neotropical migrants (NMs) and the non-neotropical migrants (non-NMs) was not significant. The 48 NM species showed an average increase of 21% (median 25%); the 53 non-NM species averaged 70% (median 75%). This appears to be a substantial difference, but because of the very large variability between species this difference is not outside the 95% confidence zone. Remember that individual species range from a drop of 99.8% to a rise of 69400% (excluding the three species that were not recorded in the 1966-1975 period and hence have an infinite percentage increase).

It is more revealing to look at the interaction between the neotropical effect and the general habitat preferences. Here are the median percent changes for the species in each category, with the number of species in parentheses:

Habitat	NM	non-NM
Forest	+20% (20)	+143% (16)
Edge/Mosaic	+32% (29)	+55% (30)
Open	-5% (7)	+43% (20)
Residential	+231% (4)	+69% (16)

In the first three habitats the neotropical migrants all show lower median changes; this reverses in the final category but there are very few neotropical migrant species that prefer residential habitats.

Looking at the average (rather than median) change, in most cases the pattern is similar with larger increases for the non-NM species in all cases:

Habitat	NM	non-NM
Forest	+43%	+208%
Edge/Mosaic	+13%	+35%
Open	-13%	+48%
Residential	+40%	+79%

In the case of the averages, statistics can be applied; the one pattern that is (highly) significant is the very large increase among the non-neotropical migrant forest species in comparison to all other categories. In the cases of the other three habitats, the smaller differences between the NM and non-NM trends are not quite statistically significant. It is interesting, though, that they all fall in the same direction.

Overall, the predominant pattern is large increases (an average of three-fold) in non-neotropical migrant forest birds, and a smaller general increase in other species (including the neotropical migrants). Of course a large number of these species do not show simple monotonic trends up or down over the entire 45 year history of the BBS; this is the topic for the next post.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Next: Inflection Points
Summary

Tennessee BBS: Ups and Downs

2011-10-09T05:37:00.000-07:00

I have heard and read comments in the recent past suggesting that in another 50 years our North American avifauna will consist of a highly depauerate relict of exotics and a few generalists, with most of our native birds religated to isolated remainders if not outright extinction. If this doomsday future is going to come to pass, it certainly is not giving any hints of itself yet in Tennessee. These 45 years of Breeding Bird Survey data for Tennessee actually paint a picture of an avifauna that remains robust, diverse, and overwhelmingly native. Though there are some major red flags, and one native species that has been effectively extirpated in recent decades, the majority of Tennessee's breeding bird species have shown statistically significant increases over this time period. Exotics are not taking over the landscape; while there have been two new arrivals during the time frame, of the three other long establish invaders two have shown flat numbers while the third has declined rather drastically. The median for the 104 species that have sufficient data to establish a meaningful trend is a 66% increase between the 1966-1975 interval and the 2001-2011 period. This looks like a sign of Apocalypse Not rather than Apocalypse Now.

Downs

As mentioned, there are some "red flag" species showing ongoing major declines in numbers, and more that have experienced smaller drops. So to get to the bad news first, these 27 species showed statistically significant declines in BBS counts (biggest loosers listed first):

Bewick's Wren
Loggerhead Shrike
Golden-winged Warbler
Yellow Warbler
Northern Bobwhite
Common Nighthawk
Gray Catbird
House Sparrow
American Redstart
Eastern Meadowlark
Northern Flicker (Yellow-shafted Flicker)
Common Grackle
Whip-poor-will
Orchard Oriole
Cerulean Warbler
Chuck-will's-widow
Black-and-white Warbler
Chimney Swift
Belted Kingfisher
Prairie Warbler
Blue Jay
Yellow-breasted Chat
Wood Thrush
Common Yellowthroat
Brown Thrasher
Northern Mockingbird
Eastern Towhee

In this list and all the remaining analyses, I have not included species that occur only on small numbers of routes (generally high-elevation birds of far east Tennessee or wetland birds of far west Tennessee) or that were not recorded in enough years to display a meaningful trend. Many of these species are ones whose declines have attracted notice and concern, such as Bewick's Wren, Loggerhead Shrike, and Northern Bobwhite. But some were surprises to me. How much concern have you heard expressed about the disappearance of Northern Flickers as a breeding species in the region? Or Gray Catbirds? Or Orchard Orioles? It is interesting to note that the majority of these species are to a fairly large degree now dependent on human activities to create and maintain their habitats -- from the obvious (House Sparrows, Chimney Swifts) to the more subtle (Thrashers in early successional habitats, Belted Kingfishers on farm ponds). I will discuss habitat and landscape-level patterns in these trends more in a forthcoming post.

Holding Steady

These next 17 species showed trends that, though no identically equal to zero, where not significantly different from it. Again they are listed in order of their percentage change, even though these changes were not statistically significant:

Green Heron
Horned Lark
Ovenbird
Field Sparrow
Eastern Screech-Owl
Grasshopper Sparrow
Eastern Kingbird
Northern Cardinal
Kentucky Warbler
Mourning Dove
Summer Tanager
Red-winged Blackbird
European Starling
Rock Pigeon
Louisiana Waterthrush
Blue-winged Warbler
Great Horned Owl

This fairly short list is quite a mixed bag of species.

Ups

Finishing with the good news, the list of gainers is quite long. These 60 species showed statistically significant gains over the period (largest increases listed last):

Indigo Bunting
Eastern Wood-Pewee
Barn Swallow
Brown-headed Cowbird
American Crow
Killdeer
Great Crested Flycatcher
Acadian Flycatcher
Yellow-throated Vireo
Red-bellied Woodpecker
Worm-eating Warbler
Broad-winged Hawk
Downy Woodpecker
Dickcissel
White-eyed Vireo
Pileated Woodpecker
Hooded Warbler
Tufted Titmouse
Red-eyed Vireo
Chipping Sparrow
Song Sparrow
Barred Owl
Red-headed Woodpecker
Wood Duck
Scarlet Tanager
American Robin
Carolina Chickadee
Purple Martin
Baltimore Oriole
American Kestrel
Northern Rough-winged Swallow
Hairy Woodpecker
Eastern Bluebird
Eastern Phoebe
Carolina Wren
Blue Grosbeak
Yellow-throated Warbler
Blue-headed Vireo
Red-tailed Hawk
American Goldfinch
Ruby-throated Hummingbird
Blue-gray Gnatcatcher
Turkey Vulture
Sharp-shinned Hawk
Warbling Vireo
Pine Warbler
Black Vulture
White-breasted Nuthatch
Red-shouldered Hawk
House Wren
Cliff Swallow
Cooper's Hawk
Cedar Waxwing
Northern Parula
Wild Turkey
Great Blue Heron
Canada Goose
Tree Swallow
Eurasian Collared-Dove
House Finch

Though this is also a diverse list, two patterns jump out as you read through it. First, as I mentioned before, this list includes all of the diurnal birds of prey plus the two vultures. Even American Kestrels, subject of much concern regionally, showed a positive trend. Though it is just hypothesizing on my part, I have to suspect that this trend must be a combination of the effects of the DDT ban and reduced persecution because of better laws, law enforcement, and awareness. I know my own rural neighbors do not routinely shoot hawks; I suspect this would not have been the case 45 years ago!

The second pattern is a larger one which I will discuss more in the next post: Most of our forest birds are on this list. As Tennessee is principally a land of forests, both at present and in our ecological past, this pattern is the primary contributor to the overall message of good news for Tennessee's breeding birds coming out of these data. We still are home to extensive forests that are some of the most biodiverse temperate ecosystems on the planet, and our avifauna continues to strongly reflect this.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Next: Habitats
Inflection Points
Summary

Tennessee BBS 9: Icterids to House Sparrow

2011-10-05T15:32:00.000-07:00

Dickcissel

35 year change: +1.90 (+70%) ± 1.65

Numbers of Dickcissels tend to bounce up and down more than those of many other species, but the overall trend has been a modest and significant increase.

Red-winged Blackbird

35 year change: +3.57 (+11%) ± 6.26

The overall net change in Redwings for the BBS era is essentially zero. The graph suggests this was the end result of about 20 years of modest increases followed by a similar decline.

Eastern Meadowlark

35 year change: -26.50 (-61%) ± 3.68

Meadowlarks have declined steadily through the BBS era, with an overall drop of roughly threefold.

Common Grackle

35 year change: -55.30 (-58%) ± 18.82

Common Grackles have also dropped steadily and substantially through the period, again showing roughly a three-fold decline overall. At the beginning of the period this was by far the most abundant species on the BBS in Tennessee; it has now descended into the pack.

Brown-headed Cowbird

35 year change: +2.96 (+32%) ± 1.18

Cowbird numbers have shown a fairly modest but statistically significant increase over the BBS period.

Orchard Oriole

35 year change: -4.34 (-52%) ± 0.48

The more common of Tennessee's two oriole species has declined steadily, with recent numbers being less than half of those at the beginning of the survey.

Baltimore Oriole

35 year change: +0.39 (+125%) ± 0.17

Baltimore Orioles are less widely distributed, with the largest counts coming from the MAV routes in northwest Tennessee. Their numbers have shown a steady increase over the BBS era.

House Finch

35 year change: +4.56 ± 1.02

After first appearing in 1987 numbers of House Finches rose sharply over the next decade. Recent data suggest a possible decline from this peak, but more years are needed to assess whether or not this is real.

American Goldfinch

35 year change: +7.98 (+220%) ± 1.75

The overall change in Goldfinch numbers is a substantial increase of more than three-fold. This appears to be constructed from a low flat line through 1980 followed by a steady climb through 2000, then a modest decline in the last decade.

House Sparrow

35 year change: -23.80 (-70%) ± 5.29

House Sparrows have declined by nearly a factor of four since the beginning of the BBS. The rate of decline appears to have moderated in the last decade or so. It is interesting to note that this decline appears to have been underway before the arrival of the House Finch as a breeding species in 1987, but the steepest drop in House Sparrows does coincide with the time of most rapid increase in House Finches.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Next: Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS 8: Towhees to Buntings

2011-10-05T15:09:00.000-07:00

Eastern Towhee

35 year change: -1.42 (-12%) ± 1.17

Towhee numbers have remained rather steady on Tennessee BBS routes. The small decline is statistically significant but is a minor change in context.

Chipping Sparrow

35 year change: +5.14 (+80%) ± 2.33

There seems to have been a "Great Sparrow Shift" around 1980 in Tennessee. Before this time, all the common species were showing rapid changes in abundance; when The Shift came their trends switched to the opposite direction or stabilized. In the case of the Chippie the initial trend was a substantial decline, which then shifted to a sustained increase. Overall the numbers rose significantly for the period.

Field Sparrow

35 year change: -3.05 (-18%) ± 3.45

For Field Sparrows, the Great Sparrow Shift was preceeded by a rapid decline amounting to a drop of over 50% in less than 10 years. After The Shift numbers gradually recovered, so that by the end of the period the net change was not significantly different from zero.

Lark Sparrow

35 year change: +0.01 (+8%) ± 0.07

Though they have been found on several different BBS routes, the data for Lark Sparrows are too limited to allow any trend to be seen.

Grasshopper Sparrow

35 year change: -0.06 (-6%) ± 0.45

This is another sparrow that shows a rapid decline of 50% or more in the beginning of the BBS period, followed by a recovery after The Great Sparrow Shift around 1980. The data are "bumpier" than those for some of the other sparrows, probably because of the loosely colonial nature of the species and the somewhat ephemeral nature of its habitat. Again, the net change for the total period was not significantly different than zero.

Song Sparrow

35 year change: +4.39 (+84%) ± 2.04

The Song Sparrow reverses the pattern shown by the other common sparrows. Its numbers rose rapidly in the early decades of the BBS, then stabilized after The Great Sparrow Shift. The overall increase for the BBS period was nearly two-fold.

Three other species of sparrows were tallied as presumed breeders on a few Tennessee BBS routes and on a very few occasions: Savannah, Vesper, and Bachman's. In all cases the data were far to skimpy to provide much information. Another species, Henslow's Sparrow, has been found in recent years to be highly local breeder at a number of sites spread over a large area of Tennessee. It has yet to be recorded on any BBS route in the state, however.

Summer Tanager

35 year change: +0.41 (+9%) ± 0.61

Summer Tanager numbers have remained stable over the BBS period, with no significant change.

Scarlet Tanager

35 year change: +1.46 (+111%) ± 0.42

In contrast, Scarlet Tanager numbers have more than doubled since the beginning of the BBS. Most of this increase happened before 1993, with fairly stable counts since then.

Northern Cardinal

35 year change: +1.34 (+4%) ± 2.84

Cardinals are abundant, ubiquitous, and show stable numbers over the BBS era.

Rose-breasted Grosbeak

35 year change: +0.02 (+628%) ± 0.02

This species has been tallied in quite variable numbers and on only a small number of BBS routes. Hence even a 628% increase is not statistically significant.

Blue Grosbeak

35 year change: +3.35 (+162%) ± 0.63

Blue Grosbeaks have increased steadily throughout the period, more than tripling in numbers from 1966 to 2010.

Indigo Bunting

35 year change: +4.374 (+11%) ± 3.08

Another of the most abundant and ubiquitous species on Tennessee BBS routes, Indigo Buntings have shown a statistically significant but fairly small increase. Overall their numbers appear to have been stable

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
Next: 9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS 7: Wood Warblers

2011-09-30T18:01:00.000-07:00

Ovenbird

35 year change: -0.36 (-18%) ± 0.43

Ovenbird numbers on Tenneessee BBS routes have fluctuated, but the overall change is not significantly different from zero.

Worm-eating Warbler

35 year change: +0.24 (+69%) ± 0.17

Worm-eating Warblers have shown a fairly steady increase in Tennessee over the BBS era.

Louisiana Waterthrush

35 year change: +0.17 (+22%) ± 0.18

Though the overall trend is not significant, Louisiana Waterthrush numbers appear to have dropped substantially between 1966 and 1980 then recovered steadily.

Blue-winged Warbler

35 year change: +0.12 (+35%) ± 0.17

The numbers of Blue-wings have remained relatively stable over the BBS period. The upswing in the last few years is due primarily to large counts on a few of stops on one route (Collinwood) where a large area of old clearcuts has reached the proper successional stage. It does not seem to be part of a large-scale trend.

Golden-winged Warbler

35 year change: -0.14 (-89%) ± 0.08

Never widespread, Golden-winged Warblers have declined steadily to the point that they have not been recorded at all since 2007.

Black-and-white Warbler

35 year change: -0.42 (-41%) ± 0.17

Numbers of Black-and-white Warblers have declined substantially over the BBS period. These data also illustrate the "Appalachian bump" that will be a prominent feature in the data for several more species below. In the early 1990s there was a sharp increase in the detection of many woodland species on eastern Tennessee routes. This appears to have been more of an observer effect than a real change in populations. It complicates the interpretation of trends for species that occur primarily or exclusicely in the eastern mountains.

Swainson's Warbler

35 year change: +0.01 (+83%) ± 0.02

Swainson's Warblers have been recorded in low numbers throughout the period, with no statistically significant trend discernable.

Kentucky Warbler

35 year change: +0.11 (+5%) ± 0.46

Though not abundant, Kentucky Warblers are widespread and have shown no significant trend in numbers over the BBS era.

Common Yellowthroat

35 year change: -3.16 (-23%) ± 0.93

Yellowthroats have shown a steady modest decline throughout the period. Even with the decline they have been one of the two most numerous warblers on Tennessee BBS routes throughout the period.

Hooded Warbler

35 year change: +0.83 (+74%) ± 0.37

Though Hooded Warbler counts have shown a statistically significant upward change, it appears that this may primarily a function of the "Appalachian bump" in the early 1990s, with flat numbers before and after the bump.

American Redstart

35 year change: -0.60 (-65%) ± 0.36

Redstart numbers have shown a substantial drop in spite of a significant "Appalachian bump" effect.

Cerulean Warbler

35 year change: -0.39 (-48%) ± 0.24

Similarly, Cerulean numbers have also dropped significantly even with a large "Appalachian bump." The data from 2009 and 2010 show a drastic drop; hopefulyl this will be reversed with 2011 data.

Northern Parula

35 year change: +2.93 (+881%) ± 0.62

Parula numbers appear to be growing exponentially, with about a 10-fold increase over the BBS period. They have now climbed to the point that they are the third most abundant wood warbler on Tennessee BBS routes, after Common Yellowthroat and the (probably not really a warbler) Yellow-breasted Chat.

Blackburnian Warbler

35 year change: +0.01 (+153%) ± 0.03

Blackburnians have been recorded in small numbers on very few routes. No significant trend is discernable from the limited data.

Yellow Warbler

35 year change: -1.78 (-87%) ± 0.26

Yellow Warblers have shown a steady, severe decline over the period, with a drop of nearly 10-fold.

Chestnut-sided Warbler

35 year change: +0.08 (+90%) ± 0.05

This is perhaps the most confusing instance of the "Appalachian bump." Numbers appeared to decline, then rose sharply in the "bump" time, with additional declines after the bump. The overall change is significantly positive, but one suspects that the bump is in fact masking an underlying long-term decline. This is where the much more refined analyses used by the BBS researchers are far more powerful than my simple approach. In the Appalachian region of Tennessee there are just not enough routes to average out the observer effects and other biases, which do appear to come out in the wash for more widespread statewide species.

Black-throated Blue Warbler

35 year change: +0.03 (+28%) ± 0.04

Black-throated Blues were found in too small numbers and on too few routes to discern a significant trend.

Pine Warbler

35 year change: +1.05 (+418%) ± 0.19

Pine Warbler numbers rose steadily through 1990. with an especially rapid rise beginning in 1985. Since 1990 numbers seem to have been roughly stable. This increase would seem likely connected to pine conversion forestry practices.

Yellow-throated Warbler

35 year change: +2.28 (+194%) ± 0.44

Numbers of this species rose steadily and substantially until the late 1990s, and appear to have stabilized since then.

Prairie Warbler

35 year change: -1.10 (-37%) ± 0.53

Prairie Warblers showed s steady, moderate decline until about 1990, with stable or slightly increasing counts since then.

Black-throated Green Warbler

35 year change: +0.46 (+104%) ± 0.24

Similar to the Chestnut-sided, this is another case where a large "Appalachian bump" seems to be obscuring what may be an overall declining trend. Numbers appear to have fallen off a cliff in 2010; the data from 2011 will illuminate whether this was just a fluke or a real event.

Canada Warbler

35 year change: +0.36 ± 0.18

Canada Warblers were found only on the Fish Springs route and only in the "Appalachian bump" period. Though the increase is statistically significant, it is probably not meaningful.

Yellow-breasted Chat

35 year change: -5.10 (-31%) ± 1.09

This anomalous warbler (which is probably not really a warbler) shows a pattern very similar to that shown by the Prairie Warbler, with which it shares many habitat preferences. Counts declined modestly until about 1990, then stabilized or perhaps rebounded somewhat. Even with the decline, Chats have been one of the two most abundant warblers on the Tennessee BBS throughout the period.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
Next: 8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS 6: Gnatcatchers to Waxwings

2011-09-30T17:47:00.000-07:00

Blue-gray Gnatcatcher

35 year change: +8.13 (+267%) ± 1.12

Still another common species that has shown a large increase in numbers on Tennessee BBS routes. Gnatcatcher counts have increased steadily by roughly a factor of four.

Eastern Bluebird

35 year change: +9.73 (+146%) ± 1.54

Though the first decade or so of the BBS appeared to show a decline in Bluebirds in Tennessee, in 1979 this turned and the overall trend for the BBS era has been strongly upwards.

Veery

35 year change: +0.01 ± 0.01

Recorded only on the Fish Springs route and only in a few years, the Veery data provide little information.

Wood Thrush

35 year change: -2.25 (-24%) ± 1.02

Wood Thrushes have declined modestly since the inception of the BBS, with most of this drop taking place between 1975 and 1990. Numbers have been quite stable in recent decades.

American Robin

35 year change: +13.21 (+113%) ± 4.36

Robin numbers increased steadily until about 1990 and have remained approximately stable since then. This is now one of the most widespread and abundant species on Tennessee BBS routes.

Gray Catbird

35 year change: -3.04 (-71%) ± 0.42

Catbirds have declined throughout the BBS period, with an especially steep drop during the 1980s. Present day counts are barely a quarter of what they were in the 1960s.

Northern Mockingbird

35 year change: -4.32 (-16%) ± 1.59

There has been a small but statistically significant drop in Mockingbird numbers, most of which took place before 1980. Mockingbirds remain abundant and widespread with stable counts in recent decades.

Brown Thrasher

35 year change: -1.15 (-21%) ± 0.68

Thrashers have also shown a small but statistically significant decline through the period.

European Starling

35 year change: +8.14 (+15%) ± 9.78

Though Starling numbers appear to have fluctuated somewhat, the change across the entire BBS era is not statistically significant. They were abundant in the 1960s, and remained just as abundant in the 2000s.

Cedar Waxwing

35 year change: +2.28 (+871%) ± 1.12

Waxwing numbers underwent a rapid shift during the late 1980s and early 1990s from a low, stable level to a much higher and more variable plateau.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
Next: 7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS 5: Larks to Wrens

2011-09-30T17:22:00.000-07:00

Horned Lark

35 year change: -0.34 (-25%) ± 0.45

Numbers of Horned Larks recorded on the BBS in Tennessee appear to have fallen, then risen, and ended up not significantly changed from where they started.

Northern Rough-winged Swallow

35 year change: +1.87 (+141%) ± 0.79

All five species of swallows recorded on the BBS in Tennessee have shown increases in numbers during the period. In the case of Rough-wings, the increase happened between 1980 and 2000, with some small retreat suggested since then.

Purple Martin

35 year change: +5.33 (+121%) ± 1.43

The significant increase in Purple Martins has happened primarily since 1995.

Tree Swallow

35 year change: +0.99 ± 0.25

As presumed breeders, Tree Swallows were unrecorded on the BBS in Tennessee until 1986; there was one 1973 report that was presumed to be late migrants. Numbers stayed low through 2000, then spiked upwards dramatically to the point that this is now an expected species on many BBS routes across the state.

Bank Swallow

35 year change: +0.10 (+2063%) ± 0.21

Bank Swallows are found infrequently and on only a very few BBS routes in Tennessee. The trend in counts has been upwards but this is not statistically significant.

Barn Swallow

35 year change: +6.30 (+26%) ± 3.53

Barn Swallows are abundant and ubiquitous on Tennessee BBS routes. Their numbers have increased less dramatically than the other swallow species in the area. Though the increase is statistically significant, overall the numbers have generally undulated around a fairly stable level.

Cliff Swallow

35 year change: +6.24 (+798%) ± 2.96

The increase in Cliff Swallows has mostly happened since 1988 and especially since 1998. As their favored habitat in this area is bridges, the BBS is generally good at detecting them. However, they are also very clumpy in distribution and subject to large shifts from year-to-year in response to bridge construction.

Carolina Chickadee

35 year change: +5.90 (+117%) ± 1.51

The roughly 2-fold increase in Chickadee numbers occurred entirely before 1990. Since then counts have been roughly stable with perhaps a slight decline

Tufted Titmouse

35 year change: +8.29 (+75%) ± 1.44

Titmouse numbers have shown a steady modest increase since about 1980.

Red-breasted Nuthatch

35 year change: +0.12 ± 0.11

Red-breasted Nuthatches have only been recorded on the Fish Springs BBS route. The marginally significant increase is not necessarily of any larger meaning.

White-breasted Nuthatch

35 year change: +3.20 (+756%) ± 0.47

White-breasted Nuthatches have increased spectacularly and steadily over the entire BBS period. The average count for the late 20-Aughts was 10-fold higher than the average for the late 1960s.

Brown-headed Nuthatch

35 year change: +0.02 ± 0.03

Brown-headed Nuthatches have been spreading dramatically through the Tennessee Valley in eastern Tennessee In recent decades. However, Tennessee BBS routes have only record the species in very small numbers so far. A major spike occurred in 2010; it will be interesting to see what 2011 data show.

Brown Creeper

35 year change: +0.003 ± 0.006

Creepers have only been recorded on the high elevation Fish Springs BBS route, and only in a few years.

Carolina Wren

35 year change: +14.58 (+154%) ± 2.31

The Carolina Wren is another common species that has shown a dramatic and sustained increase in numbers in Tennessee during the BBS era, especially since about 1980. It is now one of the most abundant and numerous species on the BBS in this state.

Bewick's Wren

35 year change: -0.66 (-100%) ± 0.19

The collapse of eastern Bewick's Wren populations region wide is well known, and the BBS data show it clearly. The species was already in a precipitous decline when the survey began in 1966; by 1979 numbers were reduced to just a small relict. The remaining populations continued a slower decline, last being found on a BBS route in Tennessee in 2005 (which was itself the first record in 7 years). Outside the BBS only a very few Tennessee nesting sites are known to still exist in a small region of the eastern Central Basin.

House Wren

35 year change: +0.63 (+786%) ± 0.18

House Wren numbers rose very slowly in the early decades of the BBS, then began a rapid climb after 1990.

Winter Wren

35 year change: +0.01 (+188%) ± 0.02

Winter Wrens are another high elevation species that have been found only on the Fish Springs route. No meaningful trends can be extracted from this meager data.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
Next: 6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS 4: Flycatchers to Corvids

2011-09-30T16:59:00.000-07:00

Eastern Wood-Pewee

35 year change: +1.43 (+22%) ± 0.65

Pewees showed a statistically significant modest upward trend in numbers on BBS routes in Tennessee, though this appears to have primarily occurred in the 1975-1990 period. Recent data suggest a possible slight decline.

Acadian Flycatcher

35 year change: +1.32 (+50%) ± 0.50

Tennessee's only widespread Empidonax species has increased significantly, especially since 1990. Though this may in part be an "Appalachian bump," the upward trend appears to be sustained up to the present

Willow Flycatcher

35 year change: -0.01 (-18%) ± 0.02

Very limited data from a small number of routes showed no significant change in numbers of this uncommon and local nesting species.

Least Flycatcher

35 year change: -0.03 (-81%) ± 0.02

Also uncommon, local, and with very limited data, the Least Flycatcher nonetheless showed a statistically significant downward trend. The skimpy data do not necessarily indicate an ecologically meaningful trend, however.

Eastern Phoebe

35 year change: +3.89 (+147%) ± 1.02

Phoebes have shown a dramatic increase on Tennessee BBS routes, especially since about 1985.

Great Crested Flycatcher

35 year change: +1.10 (+48%) ± 0.42

This species has also increased steadily, though less dramatically, throughout the BBS period.

Eastern Kingbird

35 year change: -0.24 (-5%) ± 0.70

Kingbird numbers have remained relatively stable on Tennessee BBS routes over the period.

Loggerhead Shrike

35 year change: -2.31 (-90%) ± 0.54

As has been widely noted, shrikes have declined drastically and exponentially over the BBS period. There are hints that his decline may have stabilized in the last decade or so; even if it has, it still represents a huge decline from the 1966 levels.

White-eyed Vireo

35 year change: +3.57 (+72%) ± 1.54

All five species of Vireos recorded on Tennessee BBS routes have shown substantial and statistically significant increases over the period. In the case of the White-eyed this appears to have taken the form of a rapid rise beginning rather suddenly in the 1990s.

Yellow-throated Vireo

35 year change: +1.01 (+66%) ± 0.32

This species has shown a steady, modest increase over the BBS era.

Blue-headed Vireo

35 year change: +0.16 (+195%) ± 0.07

Primarily restricted as a breeder to the eastern parts of Tennessee, the Blue-headed Vireo has increased dramatically since the early 1980s. This rise began well before the "Appalachian bump" period of the early 1990s and continues steadily to the present. This puts the apparent nesting pair I found in Lewis County in 2010 (well to the west of the typical breeding range) in context.

Warbling Vireo

35 year change: +0.52 (+363%) ± 0.14

In contrast to the Blue-headed, the Warbling Vireo is primarily a bird of west Tennessee. It has shown an even more dramatic increase in numbers, rising steadily from near zero in the 1960s to being widespread, even abundant on some routes, in recent years.

Red-eyed Vireo

35 year change: +6.05 (+77%) ± 1.07

This most ubiquitous vireo in Tennessee rose in number steadily from 1966 until about 1995, then apparently reached a plateau or even began a slight decline.

Blue Jay

35 year change: -6.94 (-34%) ± 2.35

Blue Jays are not at their most conspicuous during the BBS season but nevertheless they are detected in large numbers on nearly all routes. The average counts have declined modestly but steadily over the decades. I found it interesting that there is no noticeable effect of the arrival of West Nile Virus in the early 2000s; the decline was ongoing before then and has continued at about the same rate since.

American Crow

35 year change: +11.78 (+43%) ± 2.36

One of the most conspicuous and ubiquitous birds on the Tennessee BBS, American Crows have increased modestly over the period. Again, there is no noticeable West Nile Virus effect.

Fish Crow

35 year change: +0.05 (+175%) ± 0.06

The "other" crow is only recorded in small numbers on a few Tennessee BBS routes. The apparent upward trend is not statistically significant overall, which is more a reflection of limited data than an indicator of real stable populations.

Common Raven

35 year change: +.03 ± 0.02

Ravens did not appear on the Tennessee BBS until the 1990s, and have been recorded in small numbers on a very few routes in east Tennessee in most years since then. There is a suggestion of a continuing upward trend but the data are too limited to evaluate this statistically.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
Next: 5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS 3: Cuckoos to Woodpeckers

2011-09-29T21:22:00.000-07:00

Yellow-billed Cuckoo

35 year change: -3.60 (-37%) ± 1.92

This most common of Tennessee's two cuckoo species has shown a steady and statistically significant decline through the BBS period.

Black-billed Cuckoo

35 year change: -0.05 (-93%) ± 0.04

The Black-billed Cuckoo also showed a statistically significant decline through the period; however this is based on much less data so the real magnitude of it is harder to determine

Eastern Screech-Owl

35 year change: -0.003 (-9%) ± 0.04

Owls are not recorded very efficiently by the BBS, as the routes begin only 30 minutes before sunrise. The small numbers of Screech Owls found show no change over the period.

Great Horned Owl

35 year change: +0.02 (+101%) ± 0.04

Great Horned Owls showed no significant change from the beginning to the end of the period; however, in the middle they showed a large increase in numbers followed by a near complete retreat from this peak. Is this a real phenomenon? It is hard to say.

Barred Owl

35 year change: +0.11 (+92%) ± 0.10

Barred Owls were recorded in the largest numbers of any owl species on Tennessee BBS routes, as they are less strictly nocturnal than the other species. Their modest increase in numbers was statistically significant, and fits with the similar pattern of increases in all species of diurnal birds of prey.

Common Nighthawk

35 year change: -0.31 (-78%) ± 0.12

The three species of nightjars that occur in Tennessee are found more regularly on BBS routes than are the owls, as they are generally more vocal in the pre-dawn hours. Nighthawks showed a substantial and statistically significant decline over the period, though counts seem to have flattened out in the last decade.

Chuck-will's-widow

35 year change: -0.47 (-46%) ± 0.22

This is the most numerous night bird found on Tennessee BBS routes. It showed a curious sharp decline around 1990, with fairly stable numbers before and after this.

Whip-poor-will

35 year change: -0.40 (-52%) ± 0.20

Like the other nightjars, Whip-poor-wills showed a significant decline in Tennessee during the BBS period, with numbers stabilizing in the last decade or so.

Chimney Swift

35 year change: -5.97 (-40%) ± 2.79

Chimney Swifts showed a substantial and significant decline over the period, with most or all of it seemingly occurring since 1990.

Ruby-throated Hummingbird

35 year change: +1.07 (+231%) ± 0.32

Hummingbird numbers on Tennessee BBS routes have increased substantially throughout the period.

Belted Kingfisher

35 year change: -0.33 (-37%) ± 0.29

Kingfisher numbers seem to have shown a steady decline; because of the "bumpiness" of the counts in the first few years this trend is only marginally stastictically significant but it does seem likely to be real.

Red-headed Woodpecker

35 year change: +0.28 (+96%) ± 0.16

Of the six woodpecker species recorded on Tennessee BBS routes, the Red-headed tends to be the one with the spottiest distribution. The erratic trend shows a significant increase overall over the BBS period.

Red-bellied Woodpecker

35 year change: +4.86 (+67%) ± 1.21

Abundant and ubiquitous, this is by far the most frequently recorded woodpecker on Tennessee BBS routes. It has shown a steady and highly significant increase over the period.

Downy Woodpecker

35 year change: +1.56 (+70%) ± 0.54

This second most abundant woodpecker on the BBS in Tennessee has also shown a substantial and significant increase in numbers over the period.

Hairy Woodpecker

35 year change: +0.36 (+143%) ± 0.09

The Hairy woodpecker is consistently tallied the least often of the six woodpecker species found on Tennessee BBS routes. It has increased steadily through the BBS era, showing the largest percentage increase of the six woodpecker species.

Northern (Yellow-shafted) Flicker

35 year change: -1.92 (-58%) ± 0.54

In contrast to the other woodpeckers, Flickers have shown a steady and steep decline in numbers reported for Tennessee BBS routes. This roughly linear drop resembles that shown by Bobwhites, and gives suggestions of accelerating in recent years. Extrapolating it forwards indicates that the Flicker would effectively disappear as a breeding bird in Tennessee within the next decade or two.

Pileated Woodpecker

35 year change: +1.13 (+74%) ± 0.42

Pileateds have increased similarly to the other (non-Flicker) woodpeckers in Tennessee, though perhaps less monotonically.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
Next: 4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS 2: Vultures to Doves

2011-09-29T09:42:00.000-07:00

Vultures, Hawks, etc.

There are 11 species of vultures and diurnal birds of prey with enough BBS data for Tennessee to make meaingful graphs. All 11 of them seem to be telling the same story:

35 year change: +2.38 (+661%) ± 0.63

35 year change: +3.76 (+295%) ± 0.73

35 year change: +0.04 (+1685%) ± 0.03

35 year change: +0.06 (+2206%) ± 0.02

35 year change: +0.0012 ± 0.0011

35 year change: +0.03 (+354%) ± 0.02

35 year change: +0.17 (+841%) ± 0.07

35 year change: +0.73 (+771%) ± 0.17

35 year change: +0.12 (+70%) ± 0.10

35 year change: +0.71 (+213%) ± 0.23

35 year change: +0.44 (+130%) ± 0.29

All of these species have shown a statistically significant increase in this time, even the ones with limited data. Most of these increases have been quite large, with a median growth of nearly 8-fold. This may be an effect of the DDT ban, reduced persecution, increased food availability, or active restoration programs; it is probably a result of all these as well as other factors. Whatever the reasons, it is clear that birds of prey have had some good decades since the 1960s. Some of these increases appear to have stabilized while others seem to be continuing. Hopefully none of them will turn around anytime soon.

Killdeer

35 year change: +1.35 (+47%) ± 0.90

Only one species of shorebird has a meaningful amount of BBS data for Tennessee. There are a few scattered records for Spotted Sandpipers and American Woodcock, but not enough to provide any real information. The statistically significant increase in Killdeer numbers all happened in the first decade of the BBS. Numbers have been relatively stable since then.

Least Tern

35 year change: +0.16 (+173%) ± 0.31

Though the graph gives the impression of a substantial presence of Least Terns on Tennessee BBS routes, in reality virtually all these birds are found on one single route, PawPaw in Lake County. A single individual was also found one time a bit farther north on the Tiptonville route, also in Lake County. Hence these data are less meaningful than they might appear. Because of the large year-to-year variation, the nearly three-fold increase in the average count over the course of the survey is not statistically significant.

Rock Pigeon

35 year change: +0.74 (+21%) ± 1.22

Though there are apparent ups and downs, overall the counts or Rock Pigeons appear stable. As they tend to occur in clumps and flocks near suitable bridges, silos, and other structures, small local effects (e.g. bridge construction) can make large bumps.

Eurasian Collared-Dove

35 year change: +0.31 ± 0.17

A recent arrival in Tennessee, this alien species first turned up on a Tennessee BBS route in 1999. Numbers quickly rose; whether they will continue to rise or have begun to stabilize remains to be seen.

Mourning Dove

35 year change: +1.81 (+6%) ± 4.28

Abundant and ubiquitous, Mourning Dove counts have remained remarkably steady through the entire BBS era. The tiny increase in average counts is statistically insignificant.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
2: Vultures to Doves
Next: 3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Tennessee BBS 1: Waterfowl to Herons

2011-09-28T21:44:00.000-07:00

Of the first 15 species, 13 are water birds. Some of these are widespread statewide; many though are limited and subject to the "MAV" effect discussed in the intro.

Canada Goose

All of my graphs will be structured the same as this one. Time runs horizontally from 1966 to 2010. The blue line shows the statewide average count (birds per route) for each year; the red line shows a 5-year moving average of these same data:
35 year change: +3.31 (+69400%) ± 1.22

The Canada Goose shows a clear cut (and well-known) example of a new arrival in the region supported by introductions; in this case deliberate stocking of non-migratory populations. After the dramatic increase, numbers appear to have stabilized since about 2000.

Wood Duck
35 year change: +0.17 (+98%) ± 0.10

This widespread duck shows an interesting pattern of a steady increase followed by a more recent modest decline. The initial rise is doubtless fostered by restoration programs; the apparent recent decline is disappointing.

Mallard
35 year change: +0.19 (+39%) ± 0.59

Identifying "wild" Mallards in Tennessee in summer is a questionble proposition at best. The large majority of these birds are counted along the shore of Reelfoot Lake, hence whatever the local trend might be it is not particularly meaningful on a large scale.

Like the other "puddle" ducks, Mallards are not sampled very efficiently by the BBS. There have been a few records for other species, but not enough to be worth discussing.

Northern Bobwhite
35 year change: -26.00 (-78%) ± 2.11

This is one of the most disturbing graphs that came out of this project. Not only has this formerly abundant bird shown a drastic decline, the drop appears to be linear (possibly even accelerating). Projecting this line forward shows a Bobwhite that has been effectively extirpated from Tennessee in 2014 -- just three years away. If you look at the change from 1966 to 2010 (rather than the difference in the 10-year averages), the decline is nearly 90%. In the 1960s this was one of the most abundant species on Tennessee BBS routes; in recent years it is has not been detected at all on many of them.

Wild Turkey
35 year change:+1.03 (+1273%) ± 0.41

The converse of the Bobwhite, Wild Turkeys have increased steadily in recent years with restoration programs.

Pied-billed Grebe
35 year change:-0.01 (-43%) ± 0.02

A few Pied-billed Grebes get spotted occasionally on the MAV counts; no meaningful trend to be had from this limited data.

Double-crested Cormorant
35 year change:=0.11 (% undefined) ± 0.11

Cormorants are primarily a MAV bird on the BBS in Tennessee, so this apparent sharp recent increase is based on data from a very few counts. Still, it is marginally significant (statistically), and it agrees with generally observed trends.

Great Blue Heron
35 year change:=+1.85 (3350%) ± 0.36

One of the two widely-observed herons on the BBS in Tennessee, Great Blues showed a sharp rise between 1980 and 1990 with fairly stable numbers since then.

Green Heron
35 year change:=-0.30 (-25%) ± 0.22

The other widespread heron on the Tennessee BBS, the Green Heron has shown a slight but statistically significant downward trend. It appears that most of this decline occurred between 1980 and 1995, with stable numbers since then.

Other Herons and Egrets

Six other species in this group have been recorded with some regularity on Tennessee BBS routes. In all of these cases, the totals come almost entirely from the two MAV routes in the far northwest corner of the state. They show interesting trend lines, but these generally are not statistically significant and are as likely to reflect shifting local conditions as any larger-scale trend.

Tennessee BBS index:
Introduction
1: Waterfowl to Herons
Next: 2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

The Breeding Bird Survey in Tennessee - 45 years of data

2011-09-28T20:52:00.002-07:00

The North American Breeding Bird Survey (BBS) represents one of the most extensive long-term datasets in existence for tracking the populations of North American birds over the decades. If you are not familiar with it, the link will give you a detailed description of what it is and how it operates. In short, it consists of many hundreds of roadside routes all across the U.S. and southern Canada, which are sampled every year during the nesting season using a standardized protocol. The survey began in 1966, and many routes have been sampled continuously every year since then.

The strengths and weaknesses of the BBS data have been discussed and analyzed at length over the years. The BBS has developed sophisticated statistical methods to extract long-term trends from the data while compensating for complications such as differences between observers and routes that are not run every year. Sometimes, though, the numbers than come out of complex statistical models can feel a bit divorced from the real, in-the-field experiences of the actual observers who stood there for three minutes a stop, 50 stops per route, over five decades. I decided I wanted to have a more direct look at the basic raw numbers and how they have changed over the last 45 years, in my adopted home state of Tennessee.

Probably the major complicating factor when looking at BBS data is the observer effect. Even birders of seemingly similar skill levels will produce quite different data on the same route. We all have our unique biases -- some people tune out Cardinals but will key in to a Cerulean Warbler at 100 yards, others can spot a Cooper’s Hawk in a split second but might miss the soft murmuring of a Gnatcatcher. Many statisticians have labored for many years to find ways to account for this. My simpler take on the matter, though, is that so long as you are averaging over enough different routes, and so long as the average biases of the whole pool of obervers have not changed substantially over time, then this will come out in the wash. I was not birding in 1966, but I was in 1974 and I ran my first BBS route in 1976. So I have been around for a large portion of the BBS era. To be sure, field ID skills have changed over that time, and in substantial ways they have improved. But in a place like Tennessee, the bulk of BBS skill boils down to one thing: How well can hear and correctly identify the typical vocalizations of the expected common and uncommon species of birds in your area? The birders I learned from in 1974 might not have yet figured out all the structural differences that help tell silent Empidonaces apart, and hybrid gulls were all but Terra Incognita. But they knew perfectly well how to pick out singing Acadian, Least, and Willow Flycatchers from the morning din. I do not really think that the birders of the 1960s and 1970s were all that different, on average, from the birders I go out with now in the 3rd Millenium when it comes to aural accuity and the ability to hear and identify the songs and calls of their local avifauna. While engaging in state-of-the-art deliberations about the molt sequence of a mystery gull that might have been passed off with a glance 40 years ago, it still seems to be the same proportion who will catch the distant chattering of a Red-headed Woodpecker, and the same proportion who will overlook it.

The second major complicating factor is than not all routes are run each year. While some gold-star routes have a complete 45 year sequence, many others have missing years, in some cases long chunks of missing years. Again, for the most part this will come out in the wash if the coverage lapses are not heavily biased to particular regions. For routes in most of the state, where the avifauna is not dramatically different between areas, this seems to be the case. There are some exceptions, however.

Three routes in particular have a disproportionate effect on the averages -- two in the far northwest part of the state and one in the far northeast. In the west, Tiptonville (001) and PawPaw (002) are the only Tennessee BBS routes that sample the Mississippi Alluvial Valley (MAV), which is biogeographically quite distinct from the rest of the state. Tiptonville runs along the south shore of Reelfoot Lake for many miles, and the nearby PawPaw route covers large areas of open cropland with many intermittent ponds, passing very close to the Mississippi main channel near Island 13. Statewide totals for many species of wetland birds are almost entirely dominated by counts from these two routes, with the Moscow Route (003) in the southwest contributing some as well. Year-to-year variation in these counts tends to be quite high with the small number of routes, the extreme variability in wetland habitat conditions between years, and the random hit-and-miss of large flocks. As a for instance, I currently run the Tiptonville route myself, and in 2011 after extensive flooding in the area I had the first record for Snowy Egret on the route -- 20 of them, all in one flock in one flooded field! Clearly these sorts of incidents have very little bearing on real Statewide population trends, but they can make for impressive spikes in a graph.

In east Tennessee the higher mountains also are ecologically quite different from the rest of the state. For the first several decades of the BBS, these high elevation habitats were only minimally sampled. In the early 1990s several new routes were added and coverage stepped up on existing routes, creating an “Appalachian bump” on counts of many warblers and other woodland species when averaged statewide. To help reduce this effect, I excluded the five 900-series routes that were first added in 1989 specifically to increase coverage of the high elevation public lands. Even so, improvements and changes in coverage on the other existing routes in this region contribute some to a residual “Appalachian bump” that is still visible in many graphs, peaking around 1993-1995. After excluding the 900-series routes, there remains only one route that samples the highest elevation birds such as Winter Wrens, Veeries, and Canada Warblers -- Fish Springs (042). This route runs from Watauga Lake to south of Roan Mountain with extensive areas above 1000m elevation. As it has been sampled steadily since 1966 with only a few missing years, I included it in the tallies. Still, given its unique habitat it also shows disproprotionately in the graphs for these high mountain species, with year-to-year sampling variability and changes in observers causing quite bumpy lines! Again, the significance of these sampling bumps as indicators of real population trends is minimal. In each of these cases (the MAV and Fish Springs Effects and the “Appalachian Bump”) I will point out on a species-by-species basis when they are dominating the patterns.

My approach was very basic: Take the statewide total for each species for each year (excluding the 900-series routes), and divide it by the total number of routes surveyed. Presto, a statewide average for individuals counted per route. I then plotted these numbers out, both the individual years and a 5-year moving average to give a smoother trend line. To get an overall summary number for the long-term trend, I took the difference between the average for the first 10 years (1966-1975) and the last 10 years (2001-2010; 2011 data are not yet available). I made an error estimate for this 35-year change by calculating the standard error for the 10 paired 35-year differences (1966 versus 2001, 1967 versue 2002, etc.) and then giving the 95% (2-tailed) confidence interval.

I’ll present these data in taxonomic order in batches, starting with the next post.

Tennessee BBS index:
Introduction
Next: 1: Waterfowl to Herons
2: Vultures to Doves
3: Cuckoos to Woodpeckers
4: Flycatchers to Corvids
5: Larks to Wrens
6: Gnatcatchers to Waxwings
7: Wood Warblers
8: Towhees to Buntings
9: Icterids to House Sparrow
Ups and Downs
Habitats
Inflection Points
Summary

Downhome Breeding Birds Plus 5 Years

2011-07-04T08:08:00.000-07:00

Having completed last year my little project of running BBS-style surveys on nearly every public road in the county, this year it was time to start my 5-years-later resample. I reran the first three routes, run previously in 2006. Putting the data side-by-side, they suggest some substantial changes over that time; but three routes of 50 stops each is not a big sample. Still, it is the minimum necessary to do a paired t-test on them and look for any statistically significant changes. So I did just that.

The particulars -- square-root transformed data, N = 3, DF = 2, total species examined = 86. Note that at a significance level of p=.05 I would expect 4 or 5 spurious hits; at p=.01 I would expect about 1 spurious hit.

A total of 5 species showed a significant change (p=.05) from 2006 to 2011. Those marked with ** are also significant at the p=.01 level (2 species)

Red-tailed Hawk
Yellow-billed Cuckoo
Blue Jay**
American Crow
Scarlet Tanager**

The power of this test is very low; many species showed large differences between the two years that were not statistically significant. This is not a whole lot more than what would be expected from random data, except for one thing: ALL of these changes are increases. No species showed a significant decline.

The biggest (statistically) change was the increase in Scarlet Tanagers. This is consistent with my general impression that this bird has substantially increased in middle Tennessee since I arrived in 2002. It does not seem to have been at the expense of Summer Tanagers, however: their total for these three routes were exactly the same in 2006 and 2011.

A lot of species showed pretty large changes that were not significant using this (low power) test. Many of these changes were consistent with patterns I feel like I have been seeing in general -- for example, increases in all woodpeckers except Northern Flicker, which is decreasing. When I get the chance I hope to pull up the statewaide long-term BBS data for Tennessee and see what it shows for the larger trends.

Powering Happy Hippies?

2011-06-27T06:35:00.000-07:00

A couple of recent things have converged in my mind in the last week or two, leading me to ponder more of the quantitative aspects of this whole sustainability thing. The first of these was spending the weekend at Jeff Poppen's solstice festival, and contemplating his views on society, economy, and agriculture. As he lays out in this interview, he envisions a system that I have kind of dubbed in my head "happy hippie feudalism." I don't mean this at all as an insult; in his version the "serfs" are actually totally free agents who live a quite pleasant life. Part of his thesis is that since a farm can feed 50-100 people, why do the other 49-99 folks need to be toiling away in the capitalist economy? He envisions them as just hanging out most of the time, enjoying life, strumming guitars, and then all pitching in at the times when a lot of person-power is needed at once. There is a whole lot more to his philosophy and practice, including strongly anti-capitalist views, a belief that when you sell produce and turn it in to a commodity you destroy farming, and an adamant position that a farm MUST have animals (preferably cattle) on it to complete its functions. But since we were there on one of his "everybody come hang out, eat good food, and strum guitars" festival weekends, this is the part I was pondering the most. I was in particular contemplating whether his fundamental thesis is really viable -- can you support 50-100 people on 300 acres of land in a sustainable and happy way? His vision actually seems like a quite nice way to live for all involved, if it is possible.

I suspected that he might be underestimating the extent to which his lifestyle and productivity were supported by the fossil fuel system that holds up pretty much everything in modern life, including most contemporary organic agriculture. I saw plenty of diesel- and gasoline powered equipment, and fields that looked to have been plowed by tractors, not horses or oxen. And his produce is delivered by car and truck, even if he is giving a lot of it away for free. I never had a chance to talk to him directly about this (very hard to corner a host when he has 1000 house guests; I was lucky to get that one photo I posted last week!). So I wondered if, in the absence of these subsidies, the lifestyle of the 50-100 happy hangers-on would actually be as relaxed as he describes.

The second thing was coming across the work of Axel Kleidon of the Max Planck Institute. He does what I have long thought ecosystem ecologists needed to do (if they actually understood thermodynamics, which most don't) -- he examines the total earth system from a complete thermodynamic perspective of energy, entropy, and free energy, and looks at the disequilibrium power generation of the total earth system. This stuff is not fringe; it may be controversial (especially among those who dislike his conclusions) but it is based on sound, solid scientific principles. There is a summary of a presentation he gave in August, 2010 available online.

One of his interesting conclusions is that the earth system on average generates about 2 W/m² of useable (free energy) power. This is in contrast to about 1000 W/m² of incoming solar radiation. And, he points out, that this 2 W/m² is already being used to drive the earth system processes on which the biosphere depends -- the climate system, soil processes, the hydrologic cycle, etc. Any of this power that we divert for human uses, such as wind or hydropower, is power taken away from the rest of the earth system. In other words, less power available to drive all those "free" processes that we take for granted but without which we cannot live. He is lately catching flack from renewable energy proponents for suggesting that their favored energy sources may be more limited and have more unforseeable impacts upon the earth system than are widely appreciated.

So I put Kleidon and Poppen together, and wondered whether those 300 acres of the earth system can really power the needs of 100 people. Using the 2 W/m² rule of thumb, those 300 acres (120 ha) generate 2.4 MW of power. A person's basic biological needs are about 100 W (yes, you and a 100 W light bulb are about equivalent). So just to give them the calories to stay alive, those 300 acres could drive 24,000 people. A ridiculous conclusion, of course, since people need far more than just their basic calorie intake, and there is no way to extract all that power from the earth system without destroying it (which is one of Kleidon's major points). But, that still is a whole lot of slack, and it does not seem at all unreasonable that there is way more than enough power from those 300 acres to keep 50-100 people comfortably fed, clothed, housed, and heated without disrupting the earth system. So maybe Jeff is really on to something, even without the diesel tractors.

Going at this from a more traditional ecological perspective, how does it work out? Well, typical annual ecosystem net primary productivity (NPP) of land such as this is in the ballpark of 0.4 W/m², which works out to about 480 kW for the 300 acre farm. Those 100 happy hippies need 10 kW of food to stay alive. A very rough rule of thumb is that agriculture can convert about 10% of NPP to human food. So the 100 happy hippies only need about 20% of those 300 acres in managed agriculture to stay fed. That is definitely in the ballpark, I would think, of the size of the human footprint on the landscape that could be considered sustainable and compatible with an intact ecosystem and habitat mosaic. It might be better at 10%, in which case we are still feeding 50 happy hippies without any fossil fuel inputs. It is harder to say how much labor would be required to keep everyone fed, clothed, and housed, and if this would be low enough to allow for enough hanging out and guitar strumming for the hippies to truly be happy. But it does look like Jeff might not actally be off the mark; even without the fossil fuels his vision might well be feasible.

It certainly is vastly more feasible than many present-day visions of "sustainable green-energy futures" with a hydrogen-powered vehicle in every garage and a state of the art wind turbine on every roof where people live in energy efficient suburban comfort twiddling away on their iPads.

The Road to Ruin

2011-06-26T19:58:00.000-07:00

I received another of those "America is on the Road to Ruin" e-mails today. These things are always circulating, each one explaining how some particular sociopolitical trend, demographic group, and/or leading figurehead is destroying our nation and our society. In this particular case, it laid out a bunch of twisted and mangled demographics from the 2008 election to basically "prove" that Obama was elected by the criminal foreign drug-addicted welfare-swilling underclasses and was destroying the nation built by the hard-working middle class tax-paying white christian True Americans. As a digression, I always find it curious that this particular brand of demagoguery almost always comes from people who would self-identify as Christians, yet they are demonizing the sort of people Jesus preferred to associate with and glorifying the classes that he preached against -- that whole "comfort the afflicted, afflict the comfortable" thing they find so damned inconvenient. But I've gotten the same e-mail in the other direction too; the common thread is usually that one particular political group or movement is leading America straight to Hell.

The thing is; America and the rest of our "Global Economy" ARE on the Road to Ruin, and nobody in any of the major political or media cohorts wants to even begin to address why. It's not about collapsing values or the failure of the social contract or the illegal immigrants or even the fiscal problems. It's not about anything that our elected government has shown any interest at all in addressing. It's far more fundamental than any of these issues. The global economy is unsustainable and cannot be tweaked, regulated, incentivized, or greenificated in to sustainability. Fossil fuels are hitting their limits; sure there are massive amounts left, but the remaining stores are more expensive and more destructive to get to. "Renewables" and all that "green/clean" junk cannot in the long run provide us, in a truly sustainable fashion, with anything even remotely approaching the luxurious flood of energy we have been basking in for the last century. Financial bubbles, unemployment, fiscal crises, these are all the myriad things that play out on top of this hard, inevitable reality: something that is unsustainable will not be sustained.

So who is leading us down The Road to Perdition? Don't go pointing fingers in politics or economics. It is you, me, us, each end every one, in our own lifestyle choices. Societies and economies are not built of thousands of elected and corporate leaders; they are built of millions and billions of individuals and each one of our individual choices and actions. It is our own lifestyle expectations and demands, not the votes cast by those ignoramouses for all the wrong people, that have put us where we are now. And, at this point, is it WAY to late to do anything to stop the long, slow, massive train wreck that has already been unfolding for years.

You have control over exactly one person: yourself. It is essentially impossible to disengage from the entire economic system in which we are all embedded; even if you wanted to cease your own individual contribution to the catastrophe-in-progress that is the global economy, you will quickly find that you cannot even come close. The one big thing you can do, though, is to become aware. I mean aware of the big picture, of the huge forces on the scale of entire societies and their thermodynamic, ecological, and geophysical realities that are the real underpinning of our place and trajectory on the arc of civilization. Stop viewing everything as the result of battling factions; let go of the fantasy that if we could just elect the right people and pass (or repeal) the right laws, we could Fix The World. Don't misunderstand; electoral politics and activist movements are definitely important. But the underlying forces are far bigger than they can fundamentally alter. What they can do is help improve (or undermine) realistic, appropriate, effective responses to these huge and inevitable changes that will be dominating the decades to come, for the rest of our lives and far beyond. And what you can do is cultivate the awareness in yourself, and let it guide your own choices and actions.

Conclusive Photographic Proof

2011-06-20T09:58:00.000-07:00

I can now present definitive evidence that Jeff Poppen a.k.a. The Barefoot Farmer and I are in fact not the same person:

It was pointed out to me, though, that this is a bit like those "how many differences can you find between these two pictures" puzzles. The definitive mark at close range, of course, is beard dred versus beard braid. The braid is occasionally absent, being replaced with a wispy cascade of loose scruff; the dredlock in contrast is an invariant characteristic and its presence or absence is diagnostic. At a distance or through intervening vegetation (crowds, pickers-n-fiddlers, whatever) the generally paler, fluffier, and unconfined gizz of the farmer and his mane relative to the birder is helpful. Presence or absence of a shirt (particularly with a hawaiian print) can also be suggestive; shoes, however, are usually absent in both cases. Rumor has it that the birder is occasionally seen sporting antlers; this has not been confirmed in the peer-reviewed literature.

What, you thought I was talking about some other kind of photographic proof?

eBird Visualizations: Eurasian Collared-Dove explosion

2010-11-19T10:08:00.000-08:00

The total amount of data in eBird is starting to reach the point where some really interesting things can be done with it. In particular, enough users are putting in all their old data going back many decades that some long-term trends are starting to become evident. I decided to put together one example of this from the recent past, an animation showing the dramatic spread of the Eurasian Collared-Dove in North America over recent decades. Click on the image below to open a 775K animated GIF in a new window:

The image should play in a continuous loop after it downloads completely. It runs from 1984 until the present (through last month), one frame per year showing the aggregated data for the entire year. You can see how the expansion really began in the late 1990s, and took off explosively in the early Aughts. Note in the last few years how the numbers have begin increasing towards the south into Mexico and the eastern Caribbean as well.

The "negative" areas are of two kinds. The beige blocks are ones that contain no data; the gray blocks contain valid negative data. Note how the amount of beige drops over time steadily, from very spotty coverage in the 1980s to near continuous data across the Lower 48 and southern Canada in recent years. This spottiness makes it harder to see some of the more subtle and slower changes in populations. It also brings up one big question:

Are YOUR observations on these maps?

Putting all your lifetime's data in eBird is a time-consuming task, but it is also very rewarding. On beyond the interest of going through all your old notes and seeing all your data neatly summarized, and the satisfaction of having made your personal data available for the whole world to study and benefit from, you also have an off-site backup of all your field notes should something catastrophic befall your own copies. This "cloud-sourced" backup is hosted and managed by two institutions (Cornell and National Audubon) that have been around for quite a long time (unlike, say, Google and Flikr) and are likely to be with us for a long time to come. So, are your data on these maps, and if not, why not?

Making this animation by hand was rather slow and tedious, but I will try to put together some others over the coming weeks and months.

Whippin' Them Dawgs

2010-11-02T22:29:00.000-07:00

I haven't seen this pattern pointed out by the pundits yet, but the whoopin' the Democrats just took in the House of Representatives was especially turned on those annoying "Blue Dogs." About half of the members of the Blue Dog Coalition got voted out and placed with Republicans; these folks comprise about half of all the losses the Dems took in this election. So this might not have as big an impact on the ideological makeup of the Congress as it first seems, replacing one bunch of Pro-lifer NRA homophobes with another. Of course all the leadership positions change, but the people in these seats were already the ones road-blocking most real meaningful legislative action in congress in spite of the (now extinct) large bicameral Democratic majority.

Since no one in either party wants to talk about the real profound and fundamental problems with the American and global economies, neither gang is going to have any success at addressing them anyway.

EDIT: To those who are distraught or elated over the outcome of this latest election, I refer you to my post from six years ago, "Votes that Matter," and invite you to take some deep breaths, back up, and think large and long about individuals, society, and politics.

Phantom Followup: Bachman's Warbler

2010-10-12T12:35:00.000-07:00

In the interest of my suggestion to "put the phantoms back on our birding radar," I'll spend a little time on the other one that is a swamp bird, Vermivora bachmanii. The prospects for this species' continued existence are also debated, though with much less venom than in the case of that large woodpecker. The last undisputed sightings and photos are significantly more recent; however it is also a shorter-lived species. Still, many of the arguments about large areas and small numbers of birds apply here as well and could have allowed a tiny relict population to be missed.

Bachman's Warbler was never a well-known species. Its breeding range was apparently spotty and very poorly characterized even before the population crashed precipitously. It spanned at least from Missouri and Louisiana to South Carolina and possibly Virginia. Migrants were seen in Peninsular and insular Florida in early spring and late summer (March-April and July-August), a migration pattern shared with many birds that nest in the Deep South and winter in the Antilles.

To understand this bird you should put it in its biological and ecological context. V. bachmanii is perhaps best viewed as part of a trinity of three very closely-allied buzzy-voiced brush-loving species of Vermivora, the other two being the Blue-winged and Golden-winged Warblers. These three birds are quite similar in size, structure, voice, and apparently habitat preferences as well. They essentially form a latitudinal gradient: Bachman's in the southern bottomlands, Blue-winged in the mid-latitudes and mid-elevations, and Golden-winged farthest north and highest up.

Many have the impression that the Bachman's was a deep swamp bird of the forest primeval. But it appears that, like its buzzy brushy brethren, it was actually a bird of gaps, edges, and early-mid successional habitats within the general forest mosaic. The famous I'On Swamp where it was last documented nesting had been a rice field a few decades before the warblers were first found there. By the way, most of you probably don't know that "I'On" is just a folksy colloquial spelling of the non-rhotic Low Country pronunciation of "Iron" -- "AH-uhn." Bachman's two primary vegetation associates appear to have been cane (Arundinaria gigantea) and blackberries; it seems to have been much less particular about the overstory trees. One might hypothesize that its true breeding range once spanned nearly the entire distribution of Arundinaria, which covers most of the coastal plain and many river bottoms extending into the uplands as well. Though it had more of a preference for, or at least a tolerance of, more forest canopy than do the Blue- and Golden-wings, the critical factor is still gaps, edges, and early successional components creating the mandatory dense understory.

The successional - gap dynamics aspect of Bachman's Warbler habitat has a major implication for anyone interested in where the species might still exist: Forget about the detailed locations where it was previously found. Would you look for Blue-wing in the same spot one was found 40 years ago? Of course not. The habitat is almost surely no longer suitable. So in the case of the Bachman's, forget the I'On Swamp, forget the Congaree. If there are any out there they are much more likely to turn up in some entirely unexpected brushy spot just about anywhere in the southeast than they are to be found in these historical spots. Folks just need to keep their eyes and ears open all through the region.

V. bachmanii is of course a warbler, and we all know how to find warblers: with our ears. Like any bird of deep cover, knowing the sounds this species makes is critical to having a chance of locating any that might still exist. Vocally, Bachman's Warbler is also closely allied to the other two Buzzy-Brushies. The good folks at the Macaulay library have compiled and cleaned up the entire collection of known sound recordings of the species into one 6 minute clip -- I'd wager that far fewer people have committed this sound bite to memory than have been imprinted on the Singer Tract Ivorybill audio. It has often been described as resembling the songs of a Northern Parula; but if you listen to it in the context of the Buzzy-Brushy Trinity the resemblance in quality to the Blue-wing and Golden-wing is very close. Only two song types for the Bachman's are documented; the other two buzzy-brushies have quite a variety of alternate songs so it is very likely that the Bachman's repertoire is larger than what you hear in that audio clip. But it is also likely that the dry thin buzzy Vermivora quality is consistent and characteristic.

To help get a better sense of the nature of the Bachman's Warbler songs, I have compiled a few examples of songs from the Parula and the other two brushy-buzzies for comparison. I'll be referencing sonograms here; but in the real world you will be using your ears not a spectrograph so listening to and studying the sound clips is the most important thing. For reference, here are sonograms of the two documented song types of the Bachman's Warbler:

It's just a surmise, but as the first song came from a presumably unmated bird in Virginia while the second was from a bird on territory in an active nesting area in South Carolina, I'd think it likely that the top one represent the "primary" or "type I" song while the second represents an "alternate" or "type II" song. This distinction is common among Vermivorae and other wood warblers. Type I is more frequent early in the season and from unmated males; type II is associated with mated birds and later in summer (though any individual male can sing either song at any time -- these are birds, after all, and they don't read the books). It is also typical for the type II song to be more variable than the type I.

The tonal quality and flat staccato nature of the Bachman's songs is very reminiscent of the type II songs of the Golden-winged and Blue-winged Warblers. A good example of the Blue-wing type II song is here, with a sonogram of one individual song below:

Similarly, here are two examples of Golden-wing's alternate songs:

The Blue-wing has a bit of harshness and dryness compared to the Bachman's and Golden-wing; on the sonogram this is resolved as a visible buzz whereas in the other songs the buzz is too fast to see the individual "ticks" comprising it. This faster, "thinner" quality is also shared by the Golden-wing's well-known "see-bzz-bzz-bzz" primary song as well as the first note of the classic "seeeee-b-z-z-z-z-z-z" type I song of the Blue-wing. This is probably a pretty good guide to what a real, live Bachman's might sound like in person.

In general, the Northern Parula has a less buzzy, less staccato, more tonal quality to its songs. Below is a typical primary song:

When fully executed, this song should provide no confusion with a Bachman's Warbler or anything else. The most common alternate songs also provide little trouble, having a more complex and variable intro but still having the distinctive Parula quality and final note. One variant I have come across that can get your heart pumping, however, is essentially just the staccato, even-pitched intro to the type I song shown above, without the rising segment or the final flourish. This give you just a flat, staccato series of buzzy notes, on first impression rather similar to the second example of Bachman's Warbler (the presumed type II song). On further listening, however, the Parula-like quality has been apparent. If you look at the sonogram, you will see that the individual notes of the Parula trill are "shaped," whereas the Bachman's buzzes are structureless flat boxes. To the ear this is what gives the Parula notes more "musicality," "pitch," or "color."

Now, though, I toss in the monkey wrench. There's a fascinating recording of a Northern Parula responding to a playback of a Bachman's Warbler song, from the site of a former Bachman's nesting area in South Carolina:

This song is eerily similar to the first (presumed type I) Bachman's song; the bird was seen by the recordist so there is no doubt about its identity as a Parula. It appears as though the Parula was actually imitating the Bachman's playback. On close inspection, spectographic differences are noticeable -- the Parula notes have a visible "buzz" to them, and they are less flat in pitch, wavering up and down the scale a bit in typical Parula fashion. These characters can all be picked up by the ear as well on close listening, but there's still a very important lesson in this: An audio encounter alone will never confirm the presence of a Bachman's Warbler, even if it is documented with a recording. Still, if by lucky chance V. bachmanii is not extinct, an audio encounter with a singing male (that leads to visual contact and photographic proof) is still the best bet of finding them, and increased birder awareness of the species' vocalizations (and life history) is the best way to help this unlikely but very happy event come to pass.

As for calls other than the song, no recordings exist and the written descriptions are rather non-distinctive within the pantheon of warbler calls.

Finally, the issue of visual ID. An adult male Bachman's well seen is distinctive; the field marks are covered in those field guides that include the phantom species. In short they are black bib, gray crown with yellow forecrown, no wingbars, etc. Still, you should keep in mind that if you catch a glimpse of a small warbler singing a strange buzzy Vermivora song with yellow underparts and a black throat, it is much more likely to be a Lawrence's Warbler (Blue-wing X Golden-wing hybrid) than a Bachman's. It's probably also more likely to be a Golden-wing X Tennessee or some other weird hybrid than a real Bachman's. A good look is mandatory to see all the diagnostic features, not just a few of them; for a territorial male it should also be attainable. The females are a real challenge; the long-accepted "last photo" of the species has just been reanalyzed and found to be in reality a Yellow Warbler of the "golden" race. The same is probably true of a video circulated a few years ago of a "possible female Bachman's" in Cuba. It might not be possible to prove a female Bachman's at this point without having the bird in hand, given how much more likely any possible bird is to be an aberrant individual of some other species, or a strange hybrid between two common species. At least now for the bird in hand you would just need to retain a few feathers or a drop of blood for DNA analysis and send her on her way, rather than putting her in a museum drawer.

In summary, the basics to keep in mind to put Bachman's Warbler "back on your birding radar:"

1. Biome -- bottomlands anywhere from Missouri to Louisiana and east to the Atlantic; also migrants in peninsular Florida. Forget the "historical hotspots;" their habitat is unlikely to still be suitable.

2. Habitat -- canopy gaps, edges, clearings, openings, areas thinned by storms, etc. that have grown a thick brushy, brambly, and/or caney understory. Think blackberries, cane, and very thick

3. Voice -- the thin dry staccatto of the brushy-buzzy Vermivora complex; typically thinner and weaker than a Parula.

Of course, also remember than even if you are in perfect habitat and hear a dead-ringer song, it's still FAR more likely that you have found a funny Parula or an out-of-range Blue-wing or Golden-wing. Fortunately the other two of the buzzy brushy trinity are usually much easier than large phantom woodpeckers to actually SEE and relocate after you hear one; the same would likely be true for a Bachman's Warbler as well.

Ivorybills and Other Phantoms: A Call to Action

2010-09-22T21:15:00.000-07:00

Those who are absolutely convinced that the odds of Ivorybill persistence in the 21st Century are zero or less, and that anyone who thinks otherwise is an utter fool whose sightings of every bird anywhere should all be expunged from every database they might have slipped into, should kindly stop reading now. I'm not addressing this to you. I am writing to the other 90%+ of competent, experienced birders out there who, no matter how dubious they might be, still maintain credence in at least a small sliver of possibility.

This will be my final posting on the Ivory-billed Woodpecker barring any new discoveries. There is little (nothing) to be said that has not already been said, repeatedly, in every available venue. I am not going to review the evidence, or the discussions of the evidence. Nor am I going to repeat all the arguments about why the extinction of this species has not been demonstrated to anything even remotely resembling a statistical certainty; it's been covered in my earlier posts and in other fora. Here in my last post I'm going to talk about the future.

The noble Campephilus principalis is one of three phantom bird species in North America (north of Mexico), those whose continued existence has not been proven yet cannot be disproved either. There are other phantoms around the world. Of our three here (the other two of course being Eskimo Curlew and Bachman's Warbler) only the Ivorybill has generated a stir in the last few years, so that is the one I am directly addressing. The situation is not dissimilar for the others, however. It is abundantly clear that focused searches by teams of dedicated individuals (even large-ish teams) are simply not capable of generating enough field hours over enough terrain to either nail these suckers down or nail the lids on their coffins in any reasonable time frame or budget. There is likely only one way to accomplish this. I hereby challenge my fellow birders with the following Call to Action:

Put these phantoms back on your birding radar.

That's it. Simple enough. Quit thinking of these creatures as ghosts or yetis, and think of them as what they really are: regular old birds that are exceedingly rare if they do exist. Throw away the baggage, mythology, and psychology and just treat them like birds.

So, what does this mean, really? It means familiarizing yourself with their habits, habitats, identification, vocalizations, behavior, etc,; all the things that we stuff in our heads about many other potential rarities. Come on, you've done this for Sharp-tailed Sandpiper, you can do it for Ivory-billed Woodpeckers. It also means putting in at least some mental and logistic energy in to finding these species.

Let me spell out some specifics here in the Ivorybill case, starting with a little personal experience. Like many southern birders of my generation, I had that Singer Tract sound recording burned into my brain at an impressionable age. Whenever I have been anywhere near a swamp, I have had a little "kent" detector running in the background. But, for all those decades (as far back as the early 1970s when the odds for the species' continued existence were less miniscule than they are now), I was not the slightest bit tuned in for double knocks. Didn't know much about them, didn't think about them, didn't listen for them. And, of course, ample evidence suggests that what I was NOT listening for was probably the most likely thing I might have heard. So, I'd charge all competent birders who live in the southeast to ask themselves these questions:

-- What does a Campephilus double knock sound like? What are its distinctive characteristics (quality, pattern, timing, intensity)? What other sounds might it be confused with?

-- What about the "kent" call? Same questions.

-- If a bird that you thought might be an Ivorybill flew past you at high speed, in the few seconds you have what should you look for other than the white secondaries (which would probably have been the first thing that caught your eye)? You have a precious instant to look for a few other key marks that would help confirm or correct the ID; where do your eyes need to go? [FYI the answer here is "the head!" We have SOO many sightings of headless "Ivorybills" in flight!]

There's more to this, though, than just brushing up on these points. There's also the question of effort. There are thousands and thousands of birders roving around the southeastern U.S. If every one of them would dedicate just a few hours each year to spending time in potential Ivorybill habitat that would quickly dwarf the total effort of the official Cornell search summed over all its field seasons. Fact is, birders do occasionally stumble across the totally unsuspected, but far, far more often we find what we expect, where we expect it, and when we are looking for it. So, once a year, in late winter or early spring, go spend some time in a swamp with not an expectation but maybe with a silly hope that you might hear a double knock. What have you got to lose? As I have noted elsewhere, birders have a strong tendency to avoid closed-canopy bottomland hardwood forests. Birders have been driving by the entrance to Moss Island for year after year on their way somewhere else, almost never bothering to stop in. There are thousands of Moss Islands out there. Pay some of them a visit. And don't just all trek to the Congaree, Choctawhatchie, and Big Woods. Don't everybody keep looking in the same few places over and over. If these birds still exist, it's pretty obvious that we don't know where they are!

And if you do stumble across something that turns your head inside out and your heart upside down, take some deep breaths and remember: It's not a ghost, it's not bigfoot, it's not a space alien. It's a bird. A really really really rare bird, but still it's a bird. Treat it as such.

Given the magnitude of the task, we birders are our only hope. No one else will ever muster the skills and person-power to sort this out.

Winter vs. Pacific Wren vocalizations

2010-08-08T14:38:00.000-07:00

In just a few months it'll be Winter Wren season again for those of us who live in mid-latitudes and low elevations (i.e. not the breeding grounds). As most birders already know, this formerly cosmopolitan species has just been split into three species: Pacific Wren, Winter Wren, and Eurasian Wren. The first two of these occur in North America, of course. The breeding ranges of the two American species are well-known; however their wintering ranges are much more uncertain. There are broad areas across the central and western U.S. where either or both species might be expected; the eastern extent of the wintering range of Pacific Wren is very poorly known at this point. This winter will be a biggie as we start to sort this out.

Most birders also already know that the primary visual mark to separate these species is the throat color (rusty red for Pacific, mousy brown for Winter). But the throat color on Winter Wrens is actually rather variable and often hard to judge in shady forest understories. As you get farther east, the "bar" for calling a Pacific Wren gets higher. There's a photo of a bird from western Tennessee (Moss Island, actually) from 2009 that shows a "Winter"-type Wren with a quite rusty throat. Is this a Pacific Wren?

My opinion is that to identify this species in Tennessee or any other eastern State without a specimen you will need to use vocalizations as a critical characteristic. We may eventually find out that the Pacific is a regular bird in some areas east of the Rockies; but until then we need to treat it as a State-level rarity. Even where both species are common, these are some of those birds that prefer to be heard and not seen, so vocalizations are definitely the easy way to go.

Fortunately, the calls of the two species are distinctly different. The typical call of both is a sharp chip, often (but not always) doubled as if to say "Win-Ter, Win-Ter, Win-Ter." A good sample of an eastern Winter Wren (from Ontario) is here:

http://macaulaylibrary.org/audio/63286

The quality of the call of the eastern bird is rather similar to the chip of a Song Sparrow; in fact I think it often gets overlooked because of this, judging from the huge variability between different birders in their Winter Wren totals on Christmas Bird Counts in the southeastern U.S. The doubling of the note is characteristic, though, and usually lets you tell the wren from the sparrow.

Here is a typical sample of the corresponding call from the Pacific Wren (recorded in Oregon):

http://macaulaylibrary.org/audio/119456

The pattern is the same, but the quality is much different. It is drier and harder. Western birders liken it to the chip of a Wilson's Warbler; a sound they hear far more often than we Easterners do! Still, the warbler-like quality is quite different from the call of the eastern species, and is diagnostic.

Of course, until we know the true status of the Pacific Wren in many eastern regions you will really need to both see AND hear the bird to nail the identification; the same is true for Winter Wrens in parts of the West. I also think that, barring any specimens turning up in existing museum collections, we should get some audio recordings to document the Pacific Wren in the eastern States before thinking of adding it to any State lists. Fortunately both species are quite vocal and responsive to spishing, so that should not be too great a challenge. Even small handheld camcorders can record audio adequate for this purpose.

And, of course, after you carefully sort out the species of your "Winter" Wrens, be sure to enter the data in eBird so that we can ALL watch the emerging picture develop. The species-level split has not yet been implemented there (but likely will be before the winter birding season starts); in the meantime you can use the options for 'Winter Wren (eastern)" and "Winter Wren (western)" and they will get correctly reassigned to the species when the split is put in force.

Just some wintery thoughts during a stubborn heat wave...

Down Home Breeding Birds

2010-06-30T13:26:00.000-07:00

Over the last five years, I have been running Breeding Bird Survey-style roadside routes across my home turf of Lewis County, Tennessee; a few routes every year. My goal was to cover the vast majority of the public roads in the county, allowing for the half-mile nominal spacing of the stops. This year I finished the 13th route, completing my coverage. Next year I'll begin them all again, running two or three a year, so I will keep a 5-year moving average estimate of countywide bird numbers.

My 13 routes include an unofficial run of the same roads covered by the official Lewis Forest BBS route, which is contained entirely within Lewis County and has been run for many years by the same skilled observer. Unlike the real BBS, I did all my coverage after sunrise, generally using the first 4 hours of daylight. I also did not necessarily complete a route in a single day, frequently splitting them between two mornings. My strategy for laying out the routes was mostly to keep turning left until I was blocked (by the county line, the end of the road, or areas I had already covered), then turning around and backtracking (without making additional stops) until I could turn left again. I also added small side trips etc. as needed to avoid leaving road segments "orphaned," unsurveyed but surrounded on all sides by roads that had already been covered. This more or less made a crooked clockwise spiral in towards the center of the county; as I got down to the last few routes I needed to do more picking and choosing of strategy to fill the remaining holes. Also unlike the BBS, a single "route" is not necessarily continuous, but includes skips and backtrack sections where I did not make stops. This is also a reason for not trying to cover an entire route in one morning; the skips and backtracks take up quite a bit of time and doing 50 stops in 4 hours was not usually practical. In the end, I did succeed at covering nearly every public road in the county, totaling 650 three minute roadside point counts.

My totals for 13 routes over 5 years (2006-2010):

Canada Goose 35
Wood Duck 3
Northern Bobwhite 83
Wild Turkey 12
Great Blue Heron 7
Green Heron 11
Black Vulture 12
Turkey Vulture 86
Cooper's Hawk 2
Red-shouldered Hawk 24
Broad-winged Hawk 7
Red-tailed Hawk 3
American Kestrel 5
Killdeer 38
Rock Pigeon 37
Eurasian Collared Dove 7
Mourning Dove 268
Yellow-billed Cuckoo 85
Eastern Screech-Owl 1
Barred Owl 2
Chimney Swift 59
Ruby-throated Hummingbird 8
Belted Kingfisher 4
Red-headed Woodpecker 21
Red-bellied Woodpecker 202
Downy Woodpecker 62
Hairy Woodpecker 23
Northern Flicker 13
Pileated Woodpecker 100
Eastern Wood-Pewee 131
Willow Flycatcher 2
Acadian Flycatcher 127
Eastern Phoebe 96
Great Crested Flycatcher 100
Eastern Kingbird 43
Loggerhead Shrike 2
White-eyed Vireo 243
Yellow-throated Vireo 137
Blue-headed Vireo 1
Warbling Vireo 1
Red-eyed Vireo 336
Blue Jay 182
American Crow 456
Northern Rough-winged Swallow 19
Purple Martin 176
Tree Swallow 6
Barn Swallow 105
Cliff Swallow 183
Carolina Chickadee 134
Tufted Titmouse 581
White-breasted Nuthatch 99
Carolina Wren 434
House Wren 21
Blue-gray Gnatcatcher 297
Eastern Bluebird 181
Wood Thrush 131
American Robin 237
Gray Catbird 30
Northern Mockingbird 181
Brown Thrasher 101
European Starling 509
Cedar Waxwing 25
Blue-winged Warbler 23
Northern Parula 112
Yellow Warbler 3
Yellow-throated Warbler 78
Pine Warbler 79
Prairie Warbler 162
Cerulean Warbler 1
Black-and-white Warbler 15
Prothonotary Warbler 4
Worm-eating Warbler 38
Ovenbird 31
Louisiana Waterthrush 27
Kentucky Warbler 99
Common Yellowthroat 182
Hooded Warbler 49
Yellow-breasted Chat 282
Eastern Towhee 208
Chipping Sparrow 207
Field Sparrow 212
Henslow's Sparrow 2
Grasshopper Sparrow 5
Summer Tanager 201
Scarlet Tanager 176
Northern Cardinal 655
Blue Grosbeak 102
Indigo Bunting 455
Dickcissel 4
Red-winged Blackbird 115
Eastern Meadowlark 217
Common Grackle 178
Brown-headed Cowbird 187
Orchard Oriole 88
Baltimore Oriole 3
House Finch 62
American Goldfinch 180
House Sparrow 138

Total -- 98 species, 11,107 individuals, five highest counts (descending order): Northern Cardinal, Tufted Titmouse, European Starling, American Crow, Indigo Bunting.

There are five additional species of nocturnal birds that I know nest in the county: Great Horned Owl, American Woodcock, Common Nighthawk, Chuck-will's-widow, and Whip-poor-will. These would bring the total up to 103 species.

Very roughly, these 650 point counts probably detected about 1% of the total number of birds in the county -- more for conspicuous and roadside-loving birds, less for inconspicuous and nocturnal species, and in many cases much more likely to detect males than females. Still, to an order if magnitude, if you multiply my 5-year totals by 100 you get a very crude first-draft ballpark estimate of the total breeding population in the county. This very loose ratio is based on an extremely rough estimate that a BBS stop will effectively detect the birds in an area of about 1 ha (0.01 km², a square 100m on a side or a circle 56m in radius), the total of 650 stops (giving 6.5 km² covered), and the total area of the county of 730 km².

It is interesting to contemplate that a bird I only found once in theory likely has about 100 other undetected individuals in the county (100 Blue-headed Vireos and 200 Willow Flycatchers? The mind boggles...). That leaves me pondering what the birds might be that there really are only a few pairs of, making it very likely I would have missed them. Some reasonable candidates might be Bewick's Wren and Bachman's Sparrow, a few of which could be lingering in the many clearcuts I do not have access to. There are almost certainly some American Redstarts in the area as well, as I get them regularly on BBS routes in surrounding counties. A few pairs of Sharp-shinned Hawks spread over 730 km² could be very easy to overlook. But what of all the other, less obvious possibilities? A pair of Hooded Mergansers on a pond I can't get to, maybe? Perhaps a Black-throated Green or a Swainson's Warbler hiding in a deep hollow somewhere?

As is usual, if you take those counts, rank them, and plot them from lowest to highest on a log scale, the left (lower) part of the graph roughly approximates a straight line. This suggests that there should be approximately as many species between 0.1 and 1 as there are between 1 and 10, and the same for 0.01 and 0.1. A total of 0.01 is statistically about what you might expect for a species that there is only one of in the entire county. As there are 23 species on the list with single digit counts, this seems to be suggesting that there might be 40 more species than the 98 I actually found, in the county, at any given moment in late May or June. Clearly this sort of extrapolation is fraught with problems and easily could greatly overestimate the real number of missed species. I can't come up with 15 additional species that would not be considered extremely unusual, even unprecedented occurrences in this area at this season.

This makes you really start to ponder the mega-rarities -- Tropical Parula anyone? How about some bizarre mesoamerican flycatcher? Thing as strange as this have happened (Tropical Parula in downtown Fort Collins CO, Variegated Flycatcher in Tennessee). As my regular readers know, the fact that there are many more birds out there than what gets detected and identified by birders is a recurring theme of mine. It is a safe bet that at any given time, any given area likely contains a surprising number of mega-rarities living there quietly unnoticed. The thought that there may be dozens of birds at this very moment in my own small home county that I have never recorded here makes me just want to drop everything else and go out birding! Odds of me finding even one of them: very low; odds of this causing major adverse impacts on the rest of my life: rather high. Sigh.. still, remember that the vastness of the unknown remains much greater than the tiny fraction of the world that we are able to actually get our eyes, ears, and binoculars on.

eBird goes Global

2010-06-07T12:53:00.000-07:00

As of a few days ago, eBird is now accepting checklists from anywhere on earth. It was previously limited to the New World plus Antarctica and (for some reason) New Zealand. The new global functions are definitely still in beta mode, of course. The checklists and abundance filters for Old World regions are very course and not very regional; as a result you are presented with an extremely long list to scroll through even in places like the UK and central Europe where the diversity of the avifauna is pretty low by global standards. At this point the review and quality control are quite limited, hence many boo-boos will be slipping through until it gets more shaken out. And there is still a clear American focus, with names such as Gray Heron instead of Grey Heron and no languages but English, Spanish, and French. Obviously there's a ways to go yet before it really begins to provide the same level of access and quality for the Old World as it now does for the New.... BUT you can enter data from anywhere, for any species now! Wooo hoo!

I don't mean to criticize the work that has been done so far; not at all! This is a massive undertaking, and these are the first publicly available fruits of this labor. It is a great step forward. I just want users who go there to check it out to know that what they find now is more limited and less user-friendly than what the finished products will surely be. Better, cleaner, and more powerful functions are doubtless coming along in the near future.

For now I expect these new functions are mostly being used by Americans who have travelled to Europe, Africa, Asia, Oceania, and Australia to complete our personal datasets. When I last checked yesterday, for example, most of the data for the UK and all the data for the Czech Republic were checklists from me that I had entered in the last couple of days. I'm sure this will change. I don't know if Team eBird actually have ambitions of becoming a resource for birders around the world, or if they are thinking more of being a resource for Americans who have traveled the world.

I know I have readers from around the world; how about some of you check it out and see if you think it might be something that would be useful and interesting to birders in your home nations? I should say that in the places where it is fully implemented, like the U.S., the default checklists you are provided are much more finely tuned to location and season and far more representative of the actual common species you find in routine birding. Eventually I'd expect the same in at least the more well-birded parts of the Old World, like Europe, Australia, and the Pacific Rim. Worth noting that one of the ways that this regional precision is obtained in the U.S. is by a small army of volunteer regional editors with local expertise who fine-tune the automated filters and default checklists as well as review reports of unusual species and high counts. I'm sure the eBird crew would be very eager to hear from people that might be interested in filling similar roles in all the newly-added territories!

To hell with global warming

2010-06-03T11:10:00.000-07:00

Take one glance at what is happening in the Gulf of Mexico these last 45 days and you will see a vivid example of why it does not matter a flying copulation at the moon whether or not fossil fuel burning is warming the planet. There are many other really good reasons to drastically reduce our burning of fossil fuels. Even if the global temperature remains right where it is now, fossil fuel extraction, consumption, and (soon enough) scarcity will wreak havoc with economies, politics, and ecosystems time and time again. Once upon a time issues of energy, environment, and society were considered in a multifaceted, multidimensional framework. That was before the monolith of global warming subsumed and displaced all other topics (thanks, Mr. Vice President).

Unfortunately, recent history has pretty well demonstrated that fossil fuel consumption will only reduce (in the large-scale and long-term) in response to economic forces, not because of well-thought out (or ill-conceived) policies. When the economy either gets too sick, or the price gets to high, or both, consumption drops. Nothing else does it. Our last chance to actually transition smoothly to a less fossil-carbon-dependent world passed 30 years ago, when the American populace resoundingly rejected reality and embraced instead three decades of insane and obscene gluttonous consumption. Those who lived then might remember that for most Americans the 1970s actually afforded a fairly comfortable lifestyle (and those who were left out then are still left out now, the booms and bubbles haven't helped them). But then the decade turned, the politics turned, and "money became the long hair of the 80s." Ask an old hippie what this means if it baffles you. As a result we have run so far beyond sustainability that there's really no hope left of a soft retreat.

A 1000 Year Flood

2010-05-17T10:44:00.000-07:00

NOAA has estimated that the Great Mayday Flood of 2010 in Tennessee exceeded the expectations for a once-in-1000-years flood in many places in the state. I'll duplicate the map of estimated recurrence intervals from the linked article here (click for full size version):

Our place is in the northwest corner of Lewis County, right on the 500-year contour. To our north large areas experienced a rarer-than-once-per-millenium rainfall.

So, what does this mean? Is it a sign of the apocalypse? Is this one of those beyond-the-range-of-historical-variation freak events that would be the vanguard of rapid global climate change? At this point, one would have to say "probably not." This may seem odd given that it shattered records across the area for rainfall totals and flood heights. But rare events must always be interpreted in the large scale.

First, these estimations of quincentennial and millenial extremes are based on extrapolations from roughly 100 years of real data. We have a general idea of the frequency of extreme rainfall events within regions based on data from many stations, but we don't have 500 years of real data from any single point to validate these estimates. So there is some room to question them. But more fundamentally, the occurence of extreme events, even hyperextreme events, is to be expected. If you have 1000 watersheds, on average you would expect one of them to experience a 1000 year flood every year. Someone wins the lottery, and someone gets hit by the meteorite.

In the case of this recent event, there's an important starting point. Tennessee is a rainy place. It is one of the rainiest of the 50 United States on average. At our homestead, my records for 2002-2009 average about 58" of precipitation per year, which is typical for highland rim locations. That's just shy of being a rain forest by some criteria. The Nashville Basin averages a bit drier, but it still runs well over 40" per year on average. Rainfall is also quite variable here. Droughts and heavy rains are common. Before this year, again just from 2002-2009, we have had months with over 15" of rain and months with no measurable rain at all. Daily totals over 3" occur every year; totals over 5" have happened a couple of times before in our brief experience. So, while a 48-hour storm total of 18" might be a millennial extreme occurrence just about anywhere, Tennessee is a good place to look for one.

As for the specifics, if you look at the map and look at the area enclosed within the 1000-year contour, you'll see that it is only a small fraction of the total area of Tennessee. It's actually probably only about 1/1000th of the total land area of the Lower 48. Which means (I'm sure you are ahead of me here already), a rain event this extreme might be expected to hit an area about this size every year, SOMEWHERE within the Lower 48. It's just not very likely to hit any single particular spot. This time it hit populated areas including a State capital. Next time it might be all rural areas and attract far less attention.

You can never infer a trend from a single incident. But even given that, it appears at this point that the 1000-year flood in Tennessee is still likely to be within the expected range of extreme climate variability for the region and continent as a whole. The red flag will be if these types of events become more common. There have been some studies suggesting that this is indeed happening, but you still can't come to a solid conclusion yet.

Personally, I remain suspicious, but will defer to the probabilities at this point pending further recurrences. I'm also still keeping an eye out for a second South Atlantic hurricane; this has not yet happened, leaving the 2004 storm categorized as an isolated event without long-term implications. I also derive considerable comfort in knowing that our own bottomland homestead evidently survived the 500-year deluge with only minor consequences.

More on flooding in Hickman and Lewis Counties

2010-05-04T05:01:00.000-07:00

Yesterday was a sunny, mild day in Tennessee, which allowed people to get started on cleanup and repair after the unprecedented rains and flooding over the weekend. The small streams have mostly fallen back below flood levels, but the larger rivers are only now passing their crests and inundation around them remains extensive. Large areas in downtown and metro Nashville remain submerged.

Around our place in Lewis County, I found an unfortunate flood victim in the middle of our yard, doubtless a casualty of stranding when the waters receded (click any image for a larger version):

These next two shots show how the stream channels realigned themselves in just a few hours, sometimes by as much as several meters. You can see how one bank has been eroded away, leaving undercut steep bluffs, while a gravel bar has accreted on the other bank. There are so many of these changes around our place that it is taking me a while to find old landmarks:

Over the next few months the vegetation will begin stabilizing these new banks, the beavers will rebuild their dams in new locations, and the landscape will settle in to a new normal until the next gullywasher comes along.

A mile down our road is a typical scene:

Before the county road crews barricaded it, people were still driving over this bridge as it was their only way out. Many people remain stranded behind scenes like this. It was this possibility more than anything else that lead us to evacuate our place rather than risk being trapped for a week.

From home we headed north on Highway 48 into Hickman County. Hickman had been entirely isolated by flooded roads and cut off from communications until yesterday. Peggy's commute transects the county, so we felt the need to check out if the roads were open and passable before she attempted them in the pre-dawn darkness. As I had feared, the lowlands south of Centerville along Highway 100 had been hard hit. A typical scene:

Note the mangled fences bearing high water marks that are well up into the buildings. The jumbles of mangled debris are ubiquitous.

Another common sight is flooded and overturned vehicles:

One hopes that they were not occupied at the time!

The power substation at Centerville was flooded:

All power in the area went out, including ours, about 8:30 a.m. on Sunday, probably when this station failed. Our power came back in less than an hour; most of Hickman outside of downtown Centerville remained in the dark through yesterday.

When people don't have tap water for days on end, they get it where they can find it:

Just north of downtown Centerville our excursion came to an end at the Duck River bridge on highway 100:

Normally this bridge sits high in the air over soccer fields.

The water was clearly well over the bridge at the crest:

This would help explain why phone service has been out county wide:

As the power outage also knocked out the cell towers, there was no communication in or out for about 36 hours.

At the north end of the bridge the roadway drops down a bit into the Defeated Creek drainage. It was probably still under 6-8 feet of water; the fish camp and restaurant has disappeared entirely below the river. Clearly Peggy was not going to be commuting past this point anytime soon:

Duck River at Centerville

2010-05-03T21:51:00.001-07:00

The all-time record flooding on the Duck River at Centerville Tennessee this afternoon. This is the USGS gauge on the Highway 100 bridge which earlier recorded a crest nearly 10 feet above the previous all-time record. As you can see from the debris on the supports, the water was about five feet above this level at the crest, and well over the road surface on the bridge. Ordinarily this bridge sits far above the river, with a city park and soccer fields well below it. The bridge was still closed by floodwaters at this time and had become the major attraction in town. Centerville is without drinking water and has only had phone and electric service restored very recently.

More photos from Hickman County tomorrow.

Flood photos

2010-05-03T15:59:00.000-07:00

A few images from the flood yesterday and its aftermath here at home. So Google searches can find the right post, these pictures are from western Lewis County, Tennessee, near Hohenwald, in the drainage of Cane Creek. Click on any image to see a larger version.

Two shots snapped during our escape as the waters were rising rapidly; as you can see we might have waited a few minutes longer than would have been ideal. Looking out the windshield:

The water was less than a foot deep, but it was still unnerving. Especially considering the view to the right:

That is our across-the-street neighbor. The water is pouring over the levee of the pond to the left and across the yard. In the background on the upper right you see the roiling raging torrent of mud that is Cane Creek, normally a placid headwater stream a few feet across and a few inches deep.

Later that afternoon as the waters receded, they left us many gifts and flattened fences:

At the downstream end of our property the road was washed out:

This is not as impressive as it may seem; this road washes out about every other year on average.

Today we drove up into Hickman County, which seems to have been hit as hard as anywhere. More details and photos will follow.

14.21" / 361 mm

2010-05-03T05:12:00.000-07:00

That is the two-day storm total rainfall at my official CoCoRAHS reporting station in the orchard. There are two things that are remarkable about this number, other than its just being FRIGGIN' HUGE. First, this is a typical number for this storm! Total of of 12-16" are widespread; covering many counties, hundreds of small stream drainages, and the homes of probably close to a million people. Second, this number is so far beyond unprecedented it is hard to believe. Nashville's official NOAA 2-day storm total was 13.53". This is a new record, breaking the old record of 6.68" set in 1979 (records go back to the 1870s). In other words, this is more than twice as much rain in a 48 hour period than has ever before been recorded there in 140 years. In our case, the bulk of that rain fell between noon Saturday and noon Sunday, so if I had measured hourly increments I would probably have a 24 hour period with about 10" of rain in it.

To our north, Hickman County seems to have fallen down a black hole. Radar estimates indicate that they were one of the hardest hit counties. They are very rural and hilly, much like Lewis County where we live. The last report was at noon yesterday, when the county government issued a civil emergency statement declaring a county wide flood emergency and that the entire area was without power and communications. Another report indicated that the drinking water treatment plant had shut down. It is typical in these situations for isolated areas to drop off the media radar, to resurface days or weeks later with harrowing tales. As an indication of how bad things might be there, the automated USGS gauge on the Duck River at Centerville has been transmitting data through the flood. It shows the Duck having crested nearly 10 feet above the previous all-time record crest, with data going back at least 119 years.

I know that you can't infer much from single events, especially in an anecdotal context. But you combine things like this with the snowstorms last winter in the mid-Atlantic, and it does make you begin to seriously wonder about global weirding. We were noting that the last three places we have lived (here, Fort Collins CO, and Georgetown SC) have all experienced "100 year floods" during our time there (the Great May Day Floods of '10, the Spring Creek Flood, and Hurricane Hugo). It isn't just that these events were in the general area; they directly affected our immediate location. Something does not add up about this...

It also appears that the first person who was killed by the flooding in Nashville was a young man whom we actually know.

What a weekend...

ADDENDUM: The Nashville NWS office has prepared a summary of storm total rainfall from CoCoRAHS data. They have us mapped as 14.39" in the western edge of Lewis County; I guess they included my 0.18" from Friday in the total.

Hard to comprehend...

2010-05-02T11:56:00.000-07:00

...what is happening in middle and west Tennessee over the last two days.

Widespread rainfall totals in excess of 12" from a train of storms that refuses to quit. Every body of water in this region is setting a new "all time" flood record. Water rescues are happening in places that have not seen a drop of floodwater in decades.

I tried to ignore the sound of the rain when it started back up at 6:00 this morning, but I just couldn't. Within an hour we had gotten 4 more inches on top of already swampy ground. The creeks on both sides of the house climbed higher than we had seen before; when the water touched the corner of the house we grabbed the dogs and changes of clothes and headed for high ground. We almost waited too long, as the neighbors pond was overflowing its levee in a solid sheet of water and washing across the road. The floodwaters weren't just covering the low spots, they were forming cascading blankets across the slopes.

Sometime later this afternoon we should be able to try to see how close to home we can get to find out what has been happening there. Meanwhile the videos coming out of Nashville look like archival footage from Katrina.

ADDENDUM: Made it home, the house is fine, water entered the crawlspace but not the structure Much of our drinking water supply infrastructure was obliterated and there is damage to fences and such, probably not much that a few hundred dollars in supplies and a week's labor can't fix. We definitely are among the lucky ones in Tennessee today!

Schroedinger's Woodpecker

2010-04-25T10:19:00.000-07:00

Barring dramatic new information, the Ivory-billed Woodpecker situation has once again settled in to stalemate. Various summaries and such will be coming out in the near future, but they will be unlikely to reveal anything major that is not already known. I've got a few big-picture summary points I want to make as well. To begin, I want to review the order-of-magnitude probability issues I have gone over several times in the past.

A fundamental split in opinion can be summarized as follows:

Opinion A. If there were any out there, surely they'd have been adequately documented by now.

Opinion B. Finding a few birds in a large area is extremely difficult, and they could remain undocumented for a very long time even with many people looking.

Biologists are generally a bit math-phobic; ask anyone who has taught undergraduate genetics about the blank stares and panicky fidgeting that fill the classroom as soon as you get to population genetics and write the first equation on the board. People in general are also quite poor at comprehending the very small and the very large. Because of these two factors, most bird people have been arguing Opinions A and B based on not much more than hunch, intuition, and common sense. Those who work in other sciences, in contrast, are much more inclined to try to work with actual numbers when dealing with these matters of the huge and tiny. The order-of-magnitude approximation is a time-honored tool in most natural sciences. So here, once again, I'm going to apply this tool to Opinions A and B.

The question of how much effort it takes to find a bird can be summed up in a simple equation:

D = A*c

Here D is your detection rate, in terms of detections per hour, A is the actual abundance of the bird (birds per km²), and c is the coefficient of detectability. This coefficient is dependent on the species, time of year, habitat, etc., and your criteria for a "detection" (e.g. heard, seen, captured in a mist net, etc.). For a general and reasonable approximation, for a typical forest bird, if there's one per km² an experienced observer moving about through this square kilometer will detect it by sound or sight about once every 10 hours. This means that c has a value of 0.1 if you are dealing with hours and square kilometers. In spite of all the arguments that ivorybills should be either less conspicuous or more conspicuous than average, I'll use this nice round order-of-magnitude number.

Now we need estimates for A, abundance expressed as Ivorybills/km², under various scenarios. Estimates for the total extent of bottomland hardwoods vary, but a value used by The Nature Conservancy of 20,000 km² is typical. Using this number, if there is only one ivorybill out there, its abundance in this habitat is 0.00005 bird/km². This one individual Ivorybill would be "detected" (more on what this means later) about once for every 200,000 hours of birder effort spent in bottomland hardwoods. If there are 100 Ivorybills scattered in this region, this rate becomes once per 2000 hours of effort.

To address the Opinions A vs. B question, we need an estimate for total observer effort within this region. Here I am just going to make up order of magnitude numbers based on my own experiences as an active birder who has lived in or near the historical range of the Ivorybill for most of my life. I'm going to guess that within this region there are roughly 1000 birders who are competent, reliable, and experienced enough to be able to produce an Ivorybill report that could be granted credibility. This is on the order of 100-200 per state. I'm going to guess that each of these observers spends about 1000 hours per year afield; as this is 20 hours per week it is likely a rather generous estimate. Working with orders of magnitude, this gives us 1,000,000 hours of birding time per year in the region.

How much of this time is spent in closed canopy coastal plain bottomland forests? A quite small fraction, actually. The forested bottomlands are not a magnet for birders; in fact they are a bit of a repellant. After getting their Swainson's Warbler for the year, most birders have little additional need for this habitat. That 20,000 km² of bottomlands is about 2% of the land area within the region; most of it is inaccessible, all of it is frequently to occasionally flooded, and rich in biting insects much of the year. Hence, it seems reasonable to guess than only about 1% of this general birding effort is within this habitat, or 10,000 hours per year.

Now to combine these two ballpark numbers:

-- Individual Ivorybill within 20,000 km² of bottomlands detected every 200,000 hours

-- Birders spend 10,000 hours per year in this habitat

It's simple to figure that a lone Ivorybill would be "detected" once every 20 years.

But what does "detected" mean? In the context used so far, for a typical woodland bird, it means heard or seen well enough to "count" an individual of a species that is expected to be within the area. In the case of forest birds, this means "heard" about 90% of the time; sometimes heard faintly, distantly, and/or only once. Only about 10% of these detections will be visual; one might estimate that only about 10% of those visual detections would be "good" ones that would allow for a detailed description or the opportunity for a diagnostic photograph.

If we use this more nuanced definition of "detection," we find that once every 20 years or so, this lone Ivorybill will be heard, and not necessarily well. It would be seen about once every 200 years; most of these sightings would be "lousy." To expect a good sighting and a shot for a photo or video, you would be waiting about 2000 years.

This all scales up linearly of course. If we have 100 Ivorybills spread within this area, we still predict only one (probably lousy) sighting every 2 years, and a good sighting or photo every 20 years.

The gist of this is that small populations of mobile forest animals (say less than 100 individuals) spread over very large areas are almost impossible to detect with the typical birder effort. The scenario for 10 birds is indistinguishable from no birds at all, given the reality of honest mistakes and the possibilities of fraud.

There are two extensions to this ballpark analysis I'm going to run through. The first is the matter that all of these 20,000 km² might not be suitable habitat, which conceivably narrows the search range. The second is the matter of intensive targeted searches within smaller areas.

I'll start with the "suitable habitat" question. True, in all likelihood only an unknown fraction of all bottomland forest is actually suitable Ivorybill habitat. It is likely, though, that the "suitable habitat" is less accessible, and hence disproportionately less often visited by birders, than the more accessible, "marginal" habitats. Hence, the numbers get even worse if you try to account for this, not better -- one quarter the area with one tenth the effort, for instance.

Now for the target search scenario. Here people identify an area within which they think there is an especially high probability of finding the bird, and focus effort there. This is of course the usual method that birders and ornithologists use to find rare birds. Here a species-specific complication comes in to play. The overall consensus of historical accounts for the Ivorybill indicated that it was a highly mobile bird with a surprisingly large (and entirely forested) home range. It was generally not described as remaining within any small area for very long. Even nesting pairs were difficult to nail down. A general estimate for the size of this home range would reasonably be 10 mi², or 25 km², an area slightly more than 3 miles on a side and approximately the size of a typical breeding bird atlas block. Those who have atlassing experience might think, "surely if I had an ivorybill within one of my atlas blocks I would have found it!" Or, if you are an Ivorybill searcher, you might think that if you did get within the home range of a bird, you'd have a good chance of nailing that sucker. Think again.

A single observer within a 25 km² home range that contains one bird would expect encounters with the following frequency:

Auditory every 250 hrs
Visual every 2500 hrs
Good sighting or photo op every 25,000 hrs

Note that 25,000 hours is 10 hours a day, every day, for 6.8 years. Under the same circumstances, you'd expect some visual contact every 250 days (about 8 months) and an "I heard something suspicious" encounter every 25 days. Any wonder, then, that Tanner only found his birds with the help of a man who effectively lived in the forest full-time?

What about the Cornell scenario? They had about 10 people in the field, all day, for about 4 months each year. That's about 12,000 hours per field season. What is the expectation there, if all this effort was within the home range of this hypothetical Ivorybill, and all of it was good field time, not preoccupied with other tasks (like servicing field equipment, etc.)? That works out to 48 audio detections, 5 sightings, and a half of a photo. For Cornell's initial secret search, these numbers are somewhat high on the audio, low on the sightings, and about right on the photo (I think the Luneau video can be counted as half a photo...). Considering that I am working in orders of magnitude, it's a pretty good approximation. For comparison, look at our Moss Island searches, where we put in about about 2000 hours of effort. The prediction is for 8 audios, 0.8 sightings, and 0.08 photos. Again, this is a pretty fair agreement. The audio rate was about right, we had three uncertain glimpses (does this total to 0.8 sightings?) and were absolutely skunked on the photo front.

Even if you are in the right place, documenting a thinly spread forest bird is daunting. It's nearly impossible for a single observer; and challenging for a group of 10 observers. If you look at the total birding community over the entire historical range of this bird, it would be hard to distinguish even as many as 10-100 residual birds from the background noise of honest misidentifications and weird occurrences, with photo ops coming only a few times a century, if even that much. Some will doubtless try to turn this inside out and say "See, that proves the bird is extinct and all these reports are bogus!" which is certainly a bit of backwards logic. What it actually demonstrates is that those of Opinion A who say "If they were out there, we'd surely have found them by now" are in fact mistaken. Between 10 and 100 surviving birds is far from extinct, yet even this many birds would easily avoid "firm confirmation" of their existence for decade after decade. Thinly spread forest creatures, with very large areas within which they might be scattered, are destined to remain phantoms. Their existence will always be extremely challenging to confirm; their extinction will be essentially impossible to establish. Like it or not, this is the way of things.

What one does about this is a matter of policy, resource allocation, etc. That's a different matter. But anyone who declares that the species is "extinct" or "probably extinct" based on existing information is just voicing a personal belief. From a scientific perspective, this is not knowable. Sibley and Kaufmann were in error in concluding that the extinction of this species (and two others) was certain enough that it did not need to be included in "comprehensive" North American field guides. Of course, the same is true of those who declare that the species is definitely extant. Even if the Arkansas video were undeniably an ivorybill, and even if those double knocks I heard at Moss Island in 2009 were absolutely accepted as being the real deal, well, those two spots are only about 100 miles apart, and it's been over a year since then. Conceivably, it might have all been the same bird, it might have been the last bird, and it might be dead now. Far fetched, but not impossible. The only way this will ever be resolved is if the population manages to rebound in at least one area to a point that firm sightings and good photos can be obtained regularly. I think everyone will agree that this would be a great day; I think most would also agree that this day is not likely coming any time soon.

Schroedinger's Woodpecker is still locked up tight in that box.

"Who could have foreseen..."

2010-04-21T13:13:00.000-07:00

"...that our air travel network would be brought to its knees by a volcano in Iceland??"

A refrain I have heard several times by jabbering voices on the radio lately. The answer to this question:

ANY competent vulcanologist, hell, any geologist of any subspecies, along with millions upon millions of better-informed lay people could have told you that this was not just a possibility, but an eventual inevitability! This is up there with "who knew the levees would fail?" It still boggles the mind how deep the capacity of human societies is to imagine that their infrastructure is divinely ordained, immortal, and invincible, and therefore they need not waste a passing thought on what happens if some "act of god" (i.e. entirely ordinary and fully anticipatable natural phenomenon) interferes with it. Even in the face of breakdowns, it is all viewed as freaks and special cases, without the larger picture (society ultimately is at the mercy of nature, it does not have dominion over it) and lessons (if you can't function without one of your major social subsystems, you better do something pretty f-ing quickly to change this!) ever being noticed by any but the "fringes."

The Financial Economy

2010-04-15T20:46:00.000-07:00

According to the Late Great Douglas Adams, we have been doing this for millions of years. In this excerpt from "The Restaurant at the End of the Universe," he recounts humanity's first Financial Bubble, and the highly effective strategy that was devised to recover from it.

To set the scene -- the Golgafrincham B-Ark has crash-landed on the Earth, 2 million years before the present. The B-Ark was a clever ruse by which the Gogafrinchans rid themselves of a useless third of their population -- all the middlemen, financial planners, telephone sanitzers, etc. They concocted tales of planetary doom, and divided their population into three portions. Each would travel to a new world in a great Ark. The A-Ark would take all the great leaders and thinkers; the C-Ark would take all the people who made things and did things with real skills, and the B-Ark would take everyone else. In a grand show of kindness, the B-Ark was sent off first. The other two-thirds of the population then remained happily at home on Golgafrincham. In this scene, the Golgafrinchans (who will become the progenitors of all earthly humanity) are holding a council meeting as they attempt to build a new civilization on this pristine world. The matter of "money" has just come up; a Management Consultant is speaking, and responding to the assertion that money "does not grow on trees":

"'...since we decided a few weeks ago to adopt the leaf as legal tender, we have, of course, all become immensly rich.' ... 'But we have also,' continued the Managment Consultant, 'run into a small inflation problem on account of the high level of leaf availability, which means that, I gather, the current going rate has something like three decidous forests buying one ship's peanut. ... So in order to obviate this problem and effectively revalue the leaf, we are about to embark on a massive defoliation campaign, and ... er, burn down all the forests. I think you'll all agree that's a sensible move under the circumstances."

Things have not changed much in the intervening 2000 millennia...

Eureka

2010-03-21T09:24:00.000-07:00

Continuing the thoughts from my previous post...

I finally found a quite simple and straightforward explanation as to why it seems to be generally accepted that the entropy of blackbody radiation (such as sunlight) expanding away from its source remains unchanged. If this is true, then the thermodynamic potential of sunlight to do work (on a per joule basis -- the fraction of solar energy that can be converted to electricity or mechanical work) will remain unchanged regardless of the distance from the source. The effective yield of "useable" energy from the sunlight will depend only on the difference in temperature of the source and the temperature of the environment in which the radiation is being put to work. The explanation is straightforward, and wrong. It violates one of the other basic laws of physics (the Uncertainty Principle).

The basis of this argument is that any reversible process cannot involve any change in entropy. This is straightforward enough: if a process results in a change in entropy, then according to the Second Law it can only run one way, the way that causes total entropy to increase. A reversible process is one that can be reversed without the use of any energy or the working of any work. Reversible processes happen all the time at the molecular and subatomic levels; in the macro world where we live they are only ideal theoretical constructs, not things that can actually be built, but they serve as thought experiments to derive principles and calculate values.

Given this, the thought experiment runs as follows:

Take that theoretical blackbody cavity, filled with blackbody radiation at thermodynamic equilibrium, and poke a pinhole in it. Some of the radiation now leaks through this pinhole and radiates out in to space. A real emitter of thermal radiation can be seen as an arbitrarily large collection of these arbitratily small pinholes, so what applies to this pinhole emitter should apply to a real emitter. If you were to place a perfectly spherical, perfectly reflecting mirror perfectly centered around this pinhole, it would reflect the radiation exactly back to the pinhole, reversing the expansion of the light without doing any work or adding any energy. Hence, the expansion of the light away from the source is thermodynamically reversible, and thus the entropy of the light never changes. QED?

No, QE-non-D. Even in this theoretical world of perfect concepts, this thought experiment fails. In order for it to succeed you have to be able to exactly specify the position and momentum of a photon at three different points -- when it leaves the pinhole, when it interacts with the mirror, and when it returns to and reenters the pinhole. Any tiny deviation at any of these points will cause at least some of the photons to miss the pinhole on their return, meaning that the expansion was not actually reversed. However, you cannot simultaneously specify the exact position and momentum of a photon (or in fact anything else) ever, not even once, certainly not three times. Even a theoretical perfect mirror perfectly positioned cannot perfectly focus light. As your arbitrarily small pinhole becomes arbitrarily smaller, more and more of the photons will miss the pinhole. The same applies if the diameter of the perfectly spherical perfectly centered perfect mirror increases.

In another similar thought experiment, you can (somehow) arrange to release your blackbody radiation into the center of the perfectly spherical perfect mirror. In the classical description, the photons will continue to pulse in and out at the speed of light, expanding and contracting perfectly forever, with no change in entropy. But given the realities of uncertainty, with each pulse they will get a bit more spread out, so they will eventually be bouncing randomly around in the perfect sphere, perfectly dispersed. Remember that this is not dependent on imperfections in the mirror. An abslutely perfect mirror will yield this result.

So, the expansion of sunlight out in to the cosmos is not a thermodynamically reversible process (even if the sun were the only object in the universe, which of course it is not). The entropy of sunlight increases with distance, and its capacity to do "useful" work (in the thermodynamic sense) decreases. I don't believe I am equipped to calculate HOW MUCH it has decreased, however, so I can't tell you if it has lost a miniscule and insignificant fraction, or a large portion, of the usable energy it had when it left the sun. But I can say that the statement that it does not change is incorrect and a violation of the fundamental laws of physics.

Sunshine and Entropy

2010-03-18T15:44:00.000-07:00

[Note to regular readers: There is nothing about woodpeckers or any other kind of bird in this post.]

I have a question: What is the entropy of sunlight?

This seemingly esoteric question has been of interest to me for decades. In intermittent searching over that time I have not actually found a satisfying answer to this question, surprisingly. It would seem this would be one of the fundamental quantities in ecological energetics, as it is what makes life on earth possible.

Entropy is a thermodynamic concept that measures the disorder of a system. It also is connected directly to that portion of a source of energy that cannot be used for work. Work in this sense is defined narrowly and precisely: it is a force acting on a mass over a distance, or the freely interchangeable equivalent thereof. In the day-to-day world, works consists of pretty much everything we do; examples include making heat flow from cold to hot (the opposite of its natural tendency), moving mass uphill, pushing objects forward against inertia and friction, making air molecules vibrate to form sound, etc.

Biological activity consists of using work on a microscopic scale to build complexity and reduce entropy. By the unbreakable laws of Thermodynamics, the total entropy of a system can never decrease. If you decrease entropy here, it must increase by at least as much somewhere else. There is no way around this; there is no penalty for breaking this law because it simply and absolutely cannot be broken. So how does the ecosphere accumulate this vast structure and order, representing a vast decline in entropy on a global scale? Simple. It feeds on the photons from the sun.

Sunlight strikes the earth. All sorts of fancy things happen to this energy, and then it eventually leaves the earth again. It arrives mostly in the form of visible light; it leaves mostly in the form of infrared radiation. Overall the total number of calories that enter and leave the ecosphere in a given time frame are balanced. What has changed is the nature of this energy. The incoming photons are higher in energy that the outgoing ones; the same amount of energy embodied in high energy photons has lower entropy than it does when it is converted to low energy photons, at least in part because it takes more low energy photons to carry the same energy (more photons = more things to keep track of = less order). So the outgoing radiation carries more entropy than the incoming energy did; all this extra entropy leaving the planet is what allows living things on earth to reduce entropy locally. There in fact is an "away:" deep space. That is where we throw all this excess entropy.

The question of the entropy of the incoming sunlight has come up recently in a different context. As I mentioned earlier, an energy source that has higher entropy is less "useful" than one with lower entropy: a smaller fraction of the high entropy source can be converted to work. This is relevant now in the context of solar energy and the prospects for replacing fossil fuel energy sources with it. Fossil fuels represent a fairly low-entropy energy source; this is part of why they are so useful. They consist of complex molecules of the sort that have already dispersed a lot of their disorder and become more organized, orderly forms of matter. My intuition has always told me that sunlight must certainly be a higher entropy source -- all those photons flying willy-nilly as compared to those elaborate molecules sitting around in complex forms. If true this would mean that a calorie of sunlight would not be equivalent to a calorie of petroleum, in terms of the work it could do -- work such as, for instance, generating electricity. But, I had not been able to find the numbers in terms that made sense.

Some recent online discussions may have finally led me to an answer that I think is correct. The last piece mayhave been kicked in to place by a blog post from Stuart Staniford, rebutting posts by John Michael Greer about the weaknesses of solar energy. Interestingly, it was what I believe to be an error in Staniford's analysis that pointed out what I think may be the correct answer. From here on out the thermodynamics will get steadily thicker; soon there will be actual equations. The physics-phobic have been warned.

The fundamental question is this: Sunlight is a diffuse, rather than concentrated energy source, unlike fossil fuels. The amount of sunlight it takes to equal the energy content of a gallon of gasoline is a surprisingly large number; I'll leave it to interested readers to search this one out on their own. Staniford's position is the most widespread one: The diffuse nature of sunlight is just a technical problem. Once we collect it by various means, a calorie of sunlight is as useful as any other calorie. It is basic heat energy that can be used to drive all the things we use fossil fuels for, and just as well. Greer's thesis is that this is not actually true; that sunlight is inherently less useful than fossil fuels.

There was confusion in Greer's writings between energy quantity and energy quality, and Staniford took him to task on this. In more precise terms, energy quantity is the total amount of heat energy available; energy quality is the fraction of this energy that can be converted into work in a given environment -- note that quality is dependent on environment and is not an absolute. This quality issue is intimately related to entropy. The relation between useful energy and total energy generally looks like this:

Usable energy = H - T*S

Here H = heat energy (enthalpy in the language of chemists), T = absolute temperature (measured above absolute zero), and S = entropy. The temperature dependence of this equation is important.

What Staniford presented was the standard Carnot cycle heat engine ( by the way, any terms you might find unfamiliar will have Wikipedia pages dedicated to them -- Wiki knows everything). This is a theoretical ideal engine that converts heat into work with maximum possible efficiency. As it turns out, the two most critical variables determining how much work you get from the energy are the temperature of the input to the heat engine, and the temperature of the environment into which the heat is dissipated. The maximum possible efficiency of conversion of energy in to work is given as:

1 - (T_e/T_s)

Here T_e is the temperature of the environment, and T_s is the temperature of the source, sometimes referred to/approximated as the "flame temperature.". This is a maximum possible efficiency; real engines generally function at significantly lower efficiencies. But it does provide a key piece of information: by determining how much of the energy is "useless," it tells you the entropy content of the energy source. The useless energy is equal to T*S (temperature times entropy). So now we come to the big question:

What is the "temperature" of sunlight?

Sunlight, as it does not consist of particles with mass, does not have a "temperature" in the normal sense (kinetic energy in the form of vibrating molecules or atoms). But it does consist of particles with kinetic energy; in fact particles that have nothing but kinetic energy. Staniford in his analysis used the "blackbody temperature" of sunlight as his value, which is 5500K. Blackbody radiation is the thermal radiation given off by everything. Its frequency and amount increase with the temperature of the object -- microwaves from very cold things, x-rays from very hot things, and various forms of "light" (infrared, visible, ultraviolet) from things in between. The increase in the amount of this radiation with temperature is dramatic, increasing as the fourth power of T (double the temperature, get 16 times as much thermal radiation). The sun emits radiation with a spectrum close to what is expected by an ideal emitter (the theoretical "black body") at a temperature of 5500K. Using this value as the effective "flame temperature" of sunlight, Staniford calculated that the theoretical efficiency for a solar-powered heat engine at "room temperature" (298K) is 94%, much better than fossil fuels.

There is an implicit rationale in the choice of 5500K, the blackbody temperature of sunlight, as the flame temperature here. It comes from the notion of the entropy of the "photon gas" contained within a closed blackbody cavity of a given temperature. This cavity will be filled with photons that are constantly being emitted and destroyed. At steady state it is a bit like a confined gas, with the exception that in a real gas the molecules bounce off the container walls, whereas in the photon gas they are absorbed by the wall, which then emits new photons. This is the one circumstance where I have seen the entropy of photons clearly defined. The photon gas in the cavity has no net useable energy by definition; otherwise you could be creating energy out of nothing and getting work for free. So, since:

H - T*S = 0

then it follows that

S = H/T

This would mean that these photons could do no work at a temperature equal to their source (blackbody) temperature, and for the purposes of a Carnot engine they would have a flame temperature equal to the temperature of their source, and equal to the blackbody temperature of spectrum of light they comprise.

But there's a problem here. When you take a real confined gas, open the box, and allow it to expand into a vacuum, its entropy increases dramatically; at the same time, its temperature decreases dramatically. Why would the same thing not happen with the "photon gas?" Why would a cloud of "free-range" photons pouring out in an expanding sphere unfettered into the cosmos have the same entropy and effective temperature as "caged" photons locked in a little black box? Sticking with the gas analogy, they most certainly would not. Their entropy would be substantially higher and steadily increasing with distance from the source, and their capacity to do work would be steadily dropping -- even when you account for dilution. One joule of photons hurtling away from the sun 93 million miles away should NOT have the same free energy, useful energy, exergy, whatever you wish to call it, as one joule of photons just released from the sun an instant before. Actually, let me restate that. If you are trying to put them to work at a temperature of absolute zero, in the coldest cold and blackest black of deepest space, then yes, indeed, they will still have the same useful energy (remember it all depends on the environment -- the Universe is apparently Post-Modern, it all depends on your context and point of view). But in an environment like, say, the surface of the Earth, where temperatures are significantly higher than absolute zero, the usefulness of these photons declines with every light-microsecond they travel away from the sun.

Hence, I don't see that it makes sense to use 5500K as the "flame temperature" to apply to sunlight on the earth. One idea of temperature is that heat flows from hot to cold, and given time objects in contact will equilibrate at the same temperature. This is one manifestation of entropy -- hot next to cold is a more ordered state than is uniformly lukewarm, so as entropy increases the temperature gradient decreases. You can leave an object in full raw unfocused unfiltered sunlight 93 million miles from the sun forever and its temperature will never approach 5500K. It occurred to me that the answer to the "flame temperature of sunlight" probably ought to be the answer to this question:

When you put a "blackbody" surface in the sunlight in a vacuum, what temperature will it equilibrate at?

This will be the temperature where the amount of energy entering the surface from absorbed sunlight is equal to the amount leaving the surface from its own blackbody emissions. This is not hard to calculate. A little algebra from well-known formulae gives you:

T⁴ = P/(A*s)

Where T is absolute temperature, P is power of incoming = outgoing radiation, A is the area of the surface, and s is the Stefan-Boltzman constant. Note that T is to the fourth power, so you need to take a "tesseract root" in this formula to get the final answer. Using 1400 W/m² as the power of sunlight at the top of the earth's atmosphere, you get a temperature of 397K, which is 124C. This is the temperature that an ideal surface will equilibrate at if it is facing directly at the sun above the atmosphere. This makes more sense to me as a "flame temperature" for sunlight than the temperature of the surface of the sun. If you want higher temperatures than this, you will need to do work to concentrate the energy.

So using the heat engine formula, this means that at "room temperature" of 298K, your maximum efficiency of conversion of sunlight into work would be (1 - 298/397), or only about 25%. This indicates that the entropy of incoming sunlight is about 14 times larger than the entropy of the ideal "photon gas" at 5500K used in Staniford's calculation. A 25% maximum theoretical efficiency is a pretty lousy number for a fuel source, far below that of fossil fuels. Given that in the real world it is hard to get much better than half of these theoretical efficiencies, it would change the picture of Our Solar Future rather dramatically.

So what is it, 5500K or 397K, 94% or 25%? The 397K number makes more sense to me, for the reasons I discused above. But, we all know that you can heat things up far hotter than this by focusing and concentrating the sunlight; won't that make the heat engine run more efficiently and give you a higher yield of work from the same energy input? Perhaps, but perhaps only if you believe in perpetual motion machines.

IF (and this is a big IF), my method of calculating the effective flame temperature of sunlight and therefore the entropy of sunlight at the earth is correct, then the answer to that question is "no." IF my calculation is correct, then the 25% limit on the useable energy in terrestrial sunlight is the limit imposed by the Second Law of Thermodynamics; need I reiterate that this Law cannot be broken under any circumstances by any means (so long as you are bigger than a quark, at least)? This really is God's Law, and there is no need for heaven and hell to enforce it because there is no way to violate it. Any efficiency gains you might think you have gotten above this number by concentrating, focusing, or otherwise manipulating the sunlight will be illusory; there will HAVE to be a hidden cost or additional energy input you have forgotten about.

Imagine that this Second-Law-limited efficiency is correct, and let's see what happens if we try to up the efficiency beyond this limit. Suppose you create a heat engine using raw unconcentrated 100% intensity sunlight. Your perfect absorber will operate at 397K; you can use no more than 25% of this heat energy to create useful work without violating the Inviable Second Law. Now build a system that concentrates this energy to produce a higher temperature on a smaller area, where you might think you are getting more useful work since you have made a bigger temperature difference. However, if the work you put in to concentrating the sunlight were to be less than the additional work you got out of the sunlight, you would STILL be in violation of the Second Law. The laws of thermodynamics don't care how your contraption is built; limits are limits and if you think you are getting something for nothing you are wrong. You have just overlooked another "something" that is actually providing the first "something," which cannot really come from "nothing." So if you focus the sunlight to make it appear that you can extract more than the theoretically maximum possible work from it, you are mistaken. It might be in the work that is done in bending the light to focus it, the depreciation of the focusing apparatus this causes, and the work necessary to build and maintain the apparatus. It might be in energy losses you have forgotten to include. There might be strange particle-wave phenomena happening in the focused beam that disperse energy in ways you did not anticipate. Most likely you have forgotten to include externalities that are necessary to keep your system running. Whatever, it has to be somewhere. Otherwise you would be creating energy or destroying entropy, neither of which is possible.

This 25% versus 94% number does not make solar unusable, but it does suggest that you can expect it to be about four times as expensive as what boosters are predicting now, even when all the inefficiencies are worked out. Note that even though I used the theoretical ideal heat engine in these calculations, it really does not matter how you attempt to get work from sunlight. The thermodynamic limits are the same. Also a side note: Using sunlight to heat something is not "work." These efficiency limits do not apply there. Sunlight can heat your water or your house, and cook your food, at an efficiency limited only by the cleverness of your design. In theory 100% of the solar calories can be converted to heat -- that is just the free flow of heat from hot to cold, with no thermodynamic work involved. But the second you try to turn it into something that can drive a motor, cool a refrigerator, compress a gas, etc. then the questions of entropy, useable energy, and the Second Law come in to play.

Which leaves me at the final question that I cannot answer: Did I do this right? The blackbody temperature of sunlight and the entropy of the confined photon gas as used by Staniford do not seem like the right answer at all. But is the alternative approach I used valid? I specifically want critiques and comments from people who know substantially more about physics than I do. Have I made a freshman mistake here, and if so what is it, why is it wrong, and what is the correct approach? On the other hand, if I do have the physics correct here, then there are some intriguing implications back at my initial, long-standing interest in this topic -- the significance of all this to the ecosphere as an "entropy machine."

The Fundamentalist Theocracy of the Glorious Republic of Texas

2010-03-16T11:26:00.000-07:00

So, why exactly do we object to the suggestion that Texas might secede from the Union? This is beginning to sound like a better and better idea with each passing day. I think we should all put our full support behind the Texas Nationalist Movement. Then they'll be out of our hair and out of our politics; maybe there will even be a mass emigration from the U.S. to Texas of all the "like minded" people, and we can get some actual work done here!

Rainsongs and Bounty Hunters

2010-03-06T07:42:00.000-08:00

At this point the Daniel Dean Hepperle (alias Dan Rainsong) affair seems to be fading in to the archives of ignominy, where it belongs; let's hope no ill-advised future actions or pronouncements kick any new life in to it. But before it goes away entirely, think there is one major lesson that should be taken from it and acted upon immediately by those in a position to do so:

Withdraw any and all offers of cash rewards for Ivorybill info. Now. Today. Yesterday, if possible.

This strategy has felt unsavory from the very beginning. In the end, I think it is clear that it has been ineffective at best and probably counterproductive overall. It has not had the desired effect of encouraging sincere outdoorsmen and -women to reveal honest information. What it has done is apparently draw in an unseemly element of treasure hunters whose motivations are anything but sincere and trustworthy. Take Daniel Rainsong, as the most prominent example. This is a man who has trafficked in stolen birds and (allegedly) had his own mother declared incompetent so he could immediately clean out her life's savings to blow on his own personal ventures, including a "lawn care business." This same lawn care business has (allegedly) taken low-bid contracts and failed to follow through with the contracted work. Seriously, would you hire this person to unplug your toilet, if you knew his background? I doubt it. So why, then, should we encourage him and others like him to waste the time and resources of real government and academic scientists while he attempts to swindle cash from them?

Please, rescind the rewards and abolish the Bounty Hunters right now.

Recent History

2010-01-27T11:11:00.000-08:00

Less than a year ago, Steve Sheridan's photo from Illinois that showed an intriguing woodpecker with a red crest and white shield was made public. For quite some time before that, the photo had been known and circulated in secret.

In looking at that image, we all went to substantial lengths to explain its features and explain away its anomalies. The presence of the white shield, the absence of visible dorsal stripes, the shape of the neck stripe, all that was contemplated and discussed at length. When we found things that didn't quite add up, we attempted to account for them as tricks of light, oddities of posture, whatever. We did this even when we could not find any good supporting evidence that our hypotheses were plausible. Why did we do this? Well, because Steve appeared completely sincere and forthright about his image, and because it seemed clear that he would lose far more by fabricating an image than he could possibly gain. Even when we got the first hard data that suggested the image might be bogus, we assumed the data were wrong. Not until the third time those measurements were confirmed did the wall begin to crack; in fact, Steve actually cracked first and confessed before any of us had the chance to proclaim the image a fraud.

In the case of Steve Sheridan, both his sincerity and his photograph were faked. But why?

Steve had been searching in the area extensively. He had both audio encounters and sightings that he was unable to document with recordings or photographs. He knew there were Ivorybills there; he might have been right about this, we can't say. But he could not come up with the proof needed to get others to share his conclusion. In a fit of frustration, he fabricated the proof. In his mind he was only generating the photo that he should have been able to capture legitimately; he was not misrepresenting the presence of Ivorybills at the site, he was in fact trying to help the Ivorybills by getting others to believe in them as well. His certainty in the presence of real Ivorybills at the site probably made it easier for him to project the facade of sincerity and honesty about his bogus image. It is far easier to lie when you are convinced that the lie really could (or should) be true.

He may have been right; there may have been Ivorybills there, and he may have seen and heard them. Nonetheless, his photo was fake.

We who do not learn from our past are condemned to repeat it.

The Secret to Success

2010-01-26T22:14:00.000-08:00

The secret to success is sincerity. Once you can fake that, you've got it made.

Back Away

2010-01-26T19:45:00.000-08:00

I am washing my hands of all things Rainsong. This is not a story line or cast of characters I care to have further association with. Apologies to those who came here seeking information on the matter.

Good for a chuckle

2009-12-30T12:23:00.000-08:00

Another rare bird in another undisclosed location; nothing at all ivory about this one, however.

On the Savannah, Tennessee, Christmas Bird Count yesterday I happened across a totally unexpected male Vermilion Flycatcher (yes, at a remote cypress-lined pond). The notes I scribbled on the back of a tally sheet as soon as I got back to my truck are pretty amusing (click for full-size but not much more legible version):

In documenting rare birds, immediacy supersedes polish and flair!

Anyone in Tennessee who comes across this and wonders why they haven't seen this bird on the RBA and mailing lists, well... it is on private land used by duck hunters, not visible from any public road. In the interest of preserving landowner relations and rights and avoiding the installation of "NO TRESPASSING" signs at the site, the location isn't being revealed.

Joe Lieberman is a filthy hypocritical scumbag.

2009-12-15T11:05:00.000-08:00

Perhaps that is too nice of a description for the Senator from Pharma.

I've hated him since 2000, and he's only gotten worse. His right-wing stump speeches in the 2000 presidential campaign were probably enough all by themselves to drive the critical number of voters away from Gore. But what does he care? The Bush years were superb for his real constituency (the pharmaceutical industry). Now his only interest is protecting their predatory profit margins.

P.S. There are 40,800 hits on Google for "Joe Lieberman" scumbag.

Not San Francisco

2009-12-13T07:07:00.000-08:00

Not New York.

Not Boston.

Houston!

Suck on THAT, "Blue State" snobs!

Flashback: The 2001 Leonid Meteor Shower

2009-12-08T22:48:00.000-08:00

While sorting through some boxes of accumulated stuff from my days as a long-haul trucker, I came across this little memento from eight years back. It was scrawled in my nearly illegible scribble on the back of an envelope (that had contained the bills of lading for the shipping container full of fake Chinese christmas trees I had picked up the previous day at the Port of Los Angeles and was currently hauling to the K-Mart Distribution Center outside of Denver). I don't know who my intended audience was; I suspect they never saw it. So after a significant delay, y'all get first crack at it (transcribed as is, unedited).

For background; the return of the Leonid Meteor storms around the turn of the millenium had been eagerly anticipated for decades. It had been on my must-see list of upcoming astronomical events since I was a child. Astronomers had nailed down 2001 as one of the likely years for this to happen, and November 18th was the night. The outbursts in the previous few years had been poorly situated for North Americans; this one was expected to especially favor us.

**************

Late November 2001, on the road somewhere in the Western U.S.

Among the many hats I wear are those of the professional trucker and amateur astronomer. For the last week I kept a close eye on meteor forecasts and load assignments to try to get myself parked in clear, dark skies on the night of Nov. 18. All came together and I was in the desert in Utah under clear skies with a magnitude 6 visual limit. The only sky glow, mysteriously hanging under Leo, proved to be the Zodiacal Light. When my alarm got me up at midnight, I walked away from the stray lights of the highway and found the sickle of Leo just rising. Almost immediately, a shining yellow Leonid streaked across the sky from east to west, nearly from horizon to horizon. Over the next few minutes three more appeared low in the east, two creeping along the horizon and a third launching vertically like a rocket. This was the confirmation I needed; I returned to my truck, bundled up, and went back to settle in for the show.

By 1:00 I had counted 25 Leonids including those first four; quite an impressive tally, I thought, with the radiant only a few degrees above the horizon. In the next half hour I counted 33 Leonids; between 1:30 and 2:00 a total of 75 of them flashed into view. I put an exclamation mark beside that total in my notes, having never counted that many meteors in a half hour before. But the Leonids were just warming up.

I count meteors the simple, old-fashioned way. I just keep a tally in my head, and every 30 minutes write the number down, to enjoy the show without having to be fumbling with notepads and clocks and lights constantly. But before long I found myself having to use my fingers to keep track of how many hundreds of Leonids I had seen in each half hour. The numbers climbed exponentially: 141, 223, then 546! It might not have been of the magnitude of the colossal Leonid storms of earlier decades, but I knew I was seeing something that I would probably never see again.

At the peak of the display the sky reminded me of a forest filled with lightning bugs, flashing and winking out in ones, twos, and threes. I could just gaze at the radiant, which was quite well up by then, and see meteors flashing every few seconds all around. Along with the classic fast-flying yellow Leonids with trails lingering for a second or two, there were quite a few faint streaks that could have been easily overlooked if there had not been so many of them. The abundance of Leonids made the radiating pattern obvious, and the occasional sporadic meteors seemed almost comically lost, like someone trying to go up the down escalator.

It is hard to say if it was real or just an illusion created by random scattering, but the Leonids certainly did appear to be clustered. Pairs and threesomes seemed to come in rapid succession; at one point five Leonids flashed in one second, giving a brief hint of what the intense storms might look like. Whether there is any real definition of a "meteor storm" I do not know, but I would tend to think of this display as a heavy shpwer, not a full-on storm. The meteors were easily countable, they were not constantly filling the sky, and they did not create the feeling of "racing through space towards the radiant." These all feature prominently in the eye-witness accounts of historical Leonid storms. Whatever it is called, it was a sight to remember!

Leonids kept falling at about 1000 per hour from about 3:00 until 4:00. After that they tapered off only slowly; bright meteors were still visible several times per minute at the end of the night in the dawn twilight. It seemed to me that notable fireballs were notably lacking for the first half of the show; after 3:30 brilliant white fireballs with terminal bursts and trails that persisted for several minutes became common. At about 4:40 when the shower had dwindled to "only" 500 meteors per hour, fatigue and cold won out and I returned to the sleeper of my truck. Even then it was hard to leave the continuing rain of shooting stars outside my windshield, and I kept peeking every half hour or so until dawn finally brought the show to an end.

*******************

As a postscript, I in fact did see a second Leonid outburst the following year from my newly-acquired farm in Tennessee, which was almost as impressive as the 2001 show.

Video Success and Failure

2009-11-23T10:58:00.000-08:00

As promised a week or so ago, more comments about the recent Pearl River video and video in general...

To begin, an important question: Why did so many people, including some who had been quite skeptical of previous Ivorybill evidence, initially get such a pro-Ivorybill impression from Mike Collin's 11/5 video? I think several factors contributed to this. First, when the bird initially appears, it is flying towards the camera. This created a predictable foreshortening of the wings, making them appear narrower than they really are. This is straightforward enough; however, the wings also appeared pointed. This almost kite-like impression in these initial frames colored perception of everything that followed. Secondly, two related phenomena interacted to prevent most from even considering a Red-headed Woodpecker when they first watched the video. Though it was not explicitly stated, I think we generally assumed that the bird had been seen, not just videotaped. and was known to be a large bird. I believe we made an assumption that the video would not even have been circulated if this fact was not known; an unjustifiable assumption, of course. I don't think this assumption was made explicitly or likely even consciously; but it lurked there. This was compounded by the fact that the published and distributed video was a deinterlaced 60 fps video which plays at half speed on most media players. This fact was not stated when the video was first made available; I had to ask to get this piece of information through a couple of links of communication. Of course, this was not done with the intent of deceiving or misrepresenting; it was done to make the video clearer and easier to analyze. Nevertheless, most viewers' first viewing of this clip was at half speed, without their being aware of this, which caused the bird to appear larger with slower movements. If you take the clip and play it at double speed (i.e. true speed), the bird suddenly looks much smaller and far less Ivorybillish. These things combined very quickly -- long pointed wings, assumption of large bird consistent with its apparent flight style -- to put most viewers in a mental state where Red-headed Woodpecker did not even come to mind as an option. Once this impression is in the mind, you become much more forgiving of the things that appear later in the video that might point in other directions.

The lesson from this: Never make any judgement about a video such as this until you have full information about the circumstances of the encounter, what was seen in addition to what is on the tape, and all the possibly relevant technical aspects of the clip. This is in fact why I have never had anything to say about Mike's "fly-under video" from 2008; without having access to the full clip, rather than just selected segments, I feel that I have no context to judge what I might be seeing.

My second point is much more general. Birders do not seem to have figured out yet what to do with video. A video tends to be treated just as a big heap of poor-quality still images. There is a very strong tendency to pick out individual frames in isolation and just interpret what is and is not seen in them. This approach makes use of the worst parts of a video (the image resolution, or lack thereof, combined with numerous artifacts) and discards some of its most useful parts: the documentation of movement, structure, and dynamics. I've gone on at length in the past about the astonishing failures of big-name birders in misinterpreting and misunderstanding imaging artifacts in low-quality video frames; now I'd like to talk about this second aspect.

Some birders tend to speak of the "giss" of a bird as though it is a metaphysical, supernatural property; perhaps an aura that can only be sensed, not measured. This is of course ridiculous. True, "giss" is a "gestalt" phenomenon; indeed before the British term was popularized in this country in the mid 1980s, we in America called it "gestalt birding" not "giss birding." But, it is a gestalt that arises from the physical nature and behavior of the bird. The giss of a bird in flight is created by its physical structure and the dynamics and patterns of its movements. There is nothing mystically incomprehensible about it. All of these attributes such as "wingtip elevation," "wrist angulation," "flap rate," "bound duration," etc. are in fact components of gizz, crystalized and quantified. If you see a "gizz" difference between two videos, you should be able to quantify what is creating it and use this for real, scientific, non-mysterious comparisons to other videos. You can also pick up other consistent, taxon-specific attributes that might not be obvious to the naked eye, such as apparent wingtip shapes, the geometry of the wings on the upstroke, etc. This is the additional information that is available in a video that compensates for the generally lower image resolution. Failing to take advantage of this is a very bad idea. Videos should be examined as a whole, with each frame in context of the temporal sequence, and the added dimensions of time and kinetics used to their full advantage.

As a side note here, many people have mentioned that flight style is a "soft" character, subject to variation. Of course, this is true. But it is subject to variation only within limits. Birds don't learn how to flap fro scratch; that behavior is hard wired. Each species has a set range of flight styles that it can vary within. One will never find a Pileated Woodpecker flying like a Ruby-throated Hummingbird no matter how hard one might look. So, of course if you only have two examples to compare, there's little you can say. But if you have a large suite of comparison material you will get a much better sense of what the range of this "soft" character is, and can in fact determine if an unknown bird is within or outside of this range.

Finally, a point that was illustrated well by this recent video. When you do have the species identification correct, and you have suitable comparison material, you will see everything about the video in question fall in line behind this ID in short order. Allowing for minor glitches and transient illusions, every frame and every feature will be seen to be readily explained by and consistent with the hypothesis that the bird in the video is actually of species X. Once I had a suitable Red-headed Woodpecker video, the recent Pearl video immediately lined up with it so well (frame by frame and in its totallity) that it was clear there was little more to discuss.

It is interesting to note that this has never happened with the Luneau video and attempts to line it up with a Pileated. Only by misinterpreting image artifacts, ignoring flight style and wing dynamics, and focusing on select out-of-context frames can one even begin to line them up. Still, five years later, no one has yet produced a video of a Pileated in flight that even approximately matches the bowed-winged downstrokes of the Luneau bird. It took me one trip to the woods and 30 minutes to get a Red-headed Woodpecker video that was an exact match to the recent Pearl video, in plumage, structure, and movement. The contrast between these two experiences is informative.

The Great 21st Century USA Eclipse Bonanza

2009-11-14T17:09:00.000-08:00

Nothing about woodpeckers here (thankfully)

I happened to check what might be coming up in the next few decades in solar eclipses in North America, and was extremely happy to discover that they are going to be one of the best times for USA Eclipse Watchers in all of history! The bonanza begins in less than 8 years, on August 21, 2017, with a total eclipse that transects the lower 48 from Oregon to South Carolina. My own little homestead lies just 60 miles outside of the path of totality for this event, meaning that my eclipse chase will be quite short, indeed. Favored US cities this time include Corvallis OR, Nashville, and Charleston SC. This would have been good enough news all by itself; but there's far more. Less than seven years later, on April 8, 2024, another (longer) eclipse barely catches the extreme northwest corner of Tennessee on its way from Dallas to Buffalo. I'll only be 56 and 62 years old on these two dates; so the odds are pretty good I'll get to see two total eclipses in the next 15 years within just a couple of hundred miles of home. In the last 48 years I've only managed to see two total eclipses, one of which was a 1500 mile international drive to reach.

After this, the flood continues. Before the end of the century, the moon's umbra will cross the eastern U.S. an incredible five more times! Budding young amateur astronomers who are in their teens and twenties now should count themselves unbelievably fortunate. Even us middle-aged sorts might have a shot at one or two more. On August 12, 2045 yet another totality tracks only a couple of hundred miles southwest of here; I'll be a little past my 83rd birthday then. And if I'm really lucky might be able to be on the gulf coast on March 30, 2052 for yet another encounter with the dragon at the fine age of 90.

I guess clean living is called for, huh?

Side by Side

2009-11-13T13:46:00.000-08:00

Once I got my Red-headed Woodpecker videos from this morning processed so I could frame through them, the striking similarity between them and Mike Collins' recent bird filmed at the Pearl were so obvious that the analysis took a lot less time than I expected. So here I'll just present two side-by-side comparisons of the Collins bird and a known Red-headed Woodpecker, which should abolish all lingering doubts as to the identity of the bird. I know it did for me.

Technical info: My video was shot this morning around 9 a.m. CST at the Meriwether Lewis grave site on the Natchez Trace Parkway in Lewis County, Tennessee, about 12 miles from my house. It is the most reliable year-round spot for the species in our area, consisting of many square kilometers of lovely oak-hickory forest. My video camera is regular definition, not an HD camera like Mike's. However, I was probably considerably closer to the birds, as I was in a National Park, near a campground, and they are quite tame. I shot with manual focus at a manually set shutter speed of 1/1000s and image stabilization on; I strongly recommend all people who attempt to use consumer video cameras to document rare birds to do likewise. Fast shutter speed and no autofocus are essential for hand-held video to prevent everything from turning into hopeless blur when zoomed; use the fastest shutter speed that lighting will allow. The results are less pleasant to actually watch, having a jerky quality; but the individual frames will contain vastly more usable information. My software will only give me 30 frames per second on deinterlaced video, not 60 frames per second as Mike has. So, when I line a frame sequence up side by side between the two, I have one frame for every two of Mike's. I also avoided zooming in too far or getting too close, as I wanted the images degraded somewhat to compare better with Mike's.

Now the results:

First, a comparison of frames where the wings are fully spread during banking flight. It is these frames especially that seemed to give intriguing long pointed wings and black only near the wingtip of the Pearl River bird. These are not entirely equivalent sequences. The lighting is different; my bird is substantially less backlit and in the middle frames the white underparts are well-lit. Also, in Mike's case the bird was in powered flight and I have grabbed the frames at comparable points in successive wingbeats; my bird was engaged in a banking glide without flapping and the frames are consecutive. Still, the illustrate very well both birds in a series of similar viewing angles (click for a larger view):

The structure of the two birds is virtually identical. The shape of the white secondary patch where it is well resolved in the latter frames is also identical between the two. There does appear to be slightly less black at the wingtip of the Collins bird; however the white in the secondaries appears to end at the same spot on both birds. I suspect that the backlight has blurred out the tips of the outer primaries on the Collins bird, making the black wingtip appear somewhat reduced. I certainly see no diference at all between these two birds that suggests in any way they are not the same species.

Next, a direct frame-by-frame comparison of one full wingstroke of both. As I was able to follow the Red-headeds around as they moved actively from tree to tree, I captured their flight from a variety of angles. I have chosen the one that is imaged the most clearly from an angle most directly comparable with the Collins bird. In the case of both videos, the chosen wingbeat occurs during bounding flight, where single flaps are separated by short folded-winged ballistic bounds (I call it "cannonballing"). This is typical of flickers, Pileateds, and Red-headeds, among other species of woodpeckers, when they are covering moderate to long distances. Also in the case of both the Collins birds and the Red-headeds I photographed, the structure, dynamics, and rhythm of the individual wingbeats in bounding flight are extremely consistent. So, the two wingbeats I have chosen (one from each bird) are quite representative of their respective flight styles. I have also included a sample frame for each bird showing it in mid-bound, with wings folded, viewed from the side, to compare the silhouette of body, head, and tail (click for a larger view):

The resemblance is striking. The structure and posture of both birds at the same stage of the wingbeat is virtually identical; the timing of the wingbeats is also indistinguishable. The structure and movement of these two birds are almost exactly the same. Their folded-wing silhouettes during the bound are also essentially indistinguishable.

The bird in Mike Collins' November 5th video is, beyond all reasonable doubt, a Red-headed Woodpecker.

Dammit.

Mike Collins 11-5-2009 Video

2009-11-13T10:33:00.000-08:00

I made it out to visit the local Red-headed Woodpecker tribe this morning and shot some deliberately mediocre video of birds in flight for comparison purposes. I'll post sample frames and side-by-side comparisons later, but it is quite clear that they are a very close match to the bird in Mike Collins' recent video. Flight style, silhouette (including apparent long pointed wings in many frames, and the shape of the head and tail), and location of white in wings are extremely similar.

In addition to posting the direct comparisons, I think there's some interesting discussion to be had here about video interpretation in general and this particular video specifically. A few of the items I'll likely get in to:

--The cognitive/perceptual phenomena that lead many people, including me, to think "Wow that looks like an Ivorybill!" on first viewing, including some who have repeatedly looked at many of Mike's other videos and said quite the opposite.

--Interpreting video is not just a matter of looking at a big heap of low-quality still images; this is a relatively new thing in the birding world and overall I don't think most birders have really begun to fully comprehend it.

--Once the correct species ID is arrived at and suitable comparison material is obtained, everything lines up very neatly and consistently.

More to come...

UPDATE: More details and comparison here.

Where Do We Go From Here?

2009-11-09T20:26:00.000-08:00

The potato harvest is still coming up short...

After two field seasons at Moss Island, plus additional work at other sites in previous years, we Tennesseans have no more to show for our efforts than anyone else. The Federal money is drying up; State money has never been a very large pool; personal resources are of course always quite limited. The 2009 results were just enough to ensure that it will be very hard for us to simply abandon that patch of swamp and leave the situation dangling forever. But we'll mostly be working on private time and what small portion of the schedules of our full-time professional government wildlife biologists that can be allocated to this work.

For myself, I think I will concentrate just on the period from late February into March that has been the source of most of our encounters in both previous years. I'll probably just set aside a couple of weeks to be in the field full-time, and hope I get lucky. But the bigger question is, what should I actually do with my time? What have we not tried? What, of what we have tried, has "worked," at least sort of?

There are a few basic things, of course. Sitting still or paddling and walking quietly has been what has yielded nearly all the encounters. Time spent surveying structured transects, servicing equipment, or trying to "cover ground" by paddling or hiking at more normal speeds does not seem to count. And of course always being ready with the video camera; of the three instances when I heard double knocks in series, only once did I record anything and that was purely fortuitous. I think we can perhaps learn something from some techniques employed by hunters: they focus single-mindedly on their quarry, not being distracted by other tasks, and they always have their weapon at the ready. Clearly, from all the stories of near-misses, "Luneau moments," and things recorded purely by accident, Ivorybill hunters across the region have often been falling short on these measures. I've been figuring out the idiosyncrasies of my particular camera, and have learned how to keep it on standby all day without draining the battery, with 0.5 sec lead time needed to start capturing images, and with focus and shutter speed already preset.

But, of course, even if I had been on the ready like this for all of 2008 and 2009, I still have yet to actually SEE anything that I would have needed to shoot with the camera! Scott, Dave, and Allan all had only very quick encounters that would not have allowed them time to "get the bird" even with only a second or so of necessary lead time. Is there anything else we could be doing to increase the encounter probabilities?

Two other primary tricks used by hunters are attractants and geographic bottlenecks. The only attractant that has been widely used as been the simulated double knock. Even in the tropics when used with common species, its success rate has been variable and modest at best. It's nothing like what you get when, for instance, you play an Indigo Bunting song at a territorial male Indigo Bunting! Is this just a function of the behavior of the genus, or does it reflect on the inaccuracies of the sounds coming out of the double knocker as compared to the real thing? Bottlenecks have not necessarily been widely employed, and perhaps we should spend more time looking at aerial photos while thinking about a wide-ranging, obligate forest interior species. Interestingly, several riparian corridors converge on the southeastern corner of Moss Island, very close to our Rhodes Lake "hot zone."

The one final thing which has actually been effective at Moss Island is simple person power. Days when we had four or more people in the field were substantially more likely to yield something. Pulling this together with the other thoughts above, I can think of three strategies for the limited time in 2010. First, just siting in the woods east of Rhodes Lake, trying to stay awake, waiting for something to happen. Second, studying the maps further and exploring some of the surrounding areas that the riparian corridors connect to. Third, arrange a couple of weekend "big sits" to fill the "hot zone" with stationary, alert, equipped observers for a couple of days. None of this is new; but having perhaps narrowed down the season and location better it might improve the odds a small bit.

As for the grand scheme, Moss Island is just a microcosm of the larger pattern. Everyone remains in limbo, finding too much to just quit, not enough to conclude anything. If there really are Ivorybills behind any of this, there seem to be an extremely small number of them. This makes the quest simultaneously almost futile and even more important. No one knows how to proceed, and everyone seems to be shutting down or scaling back. This will mostly leave the freelancers on their own in the field, plus the occasional chance encounter, rumors from hunters, and similar things. If the beasts are still out there, they have managed this far without our direct assistance; indeed, "being found" has never really helped these birds. The Singer Tract got clearcut just the same, after all. In the Big Woods the birding community has shown a marked preference for image artifacts and incredible space-time bending white bleed over a living Ivorybill. A metaphysical sort might wonder why the critters would even bother with showing themselves to us for all the good it has ever done for them!

And now, 31 blog posts later, I'm afraid this is where I have to leave the tale. Thank you all for reading (slogging through?) to the end.

Someday, somewhere, somehow, someone has GOT to see whatever the hell it is that is making these double knocks.

Other posts in this series:
First
Previous

Developing Story

2009-11-06T13:56:00.000-08:00

To divert from finishing the Moss Island tale for a moment...

Mike Collins has posted several recent videos at his Pearl River search log. One of these does seem to clearly show a large woodpecker with backlight shining brightly through its secondaries, for a couple of wingbeat cycles. Today he has posted a single frame from a new video. This frame seems to show a bird with rather long, pointed wings, almost kite-like, that seems to have light underwings with a narrow dark area at the tip. If the rest of the video makes it clear that this is actually a large woodpecker, this would indeed be exceedingly interesting.

It'll be interesting to see the rest of the video and hear the tale that goes with it, especially such things as if the bird was actually seen, not just videoed, under circumstances that confirm it was a LARGE woodpecker. That underwing pattern can be vaguely approximated by an oddly-positioned Red-headed Woodpecker, though not really very well. The black doesn't look extensive enough.

Wait and see, as always...

Update Nov. 7, 2009:

Mike has made the latest video available. Paralleling the reactions of many people, my first impression was very positive; my second impression becomes more careful. Some legitimate concerns have been voiced that I am not sure I agree with, but I do see than they need to be taken seriously. I'll not be making any public declarations about the bird in this video until after I have had a chance to go through it exhaustively and in comparison to videos of other woodpeckers of known species. When looking at a video like this, there is a tendency to pull out individual frames that tend to make one lean one way or another. But, if you have correctly identified the bird in the video, then EVERY frame in the video should be consistent and easily reconcilable with the ID you propose using uniform criteria (i.e. not invoking one set of distortions for some frames and other completely different distortions for other frames). Individual frames are most valuable in context, not in isolation. I remember that it took me months of staring at the Luneau video and extensive Pileated comparison material before I finally satisfied myself that every frame was consistent with Ivorybill and many were not consistent with Pileated. I don't think it'll take that long in this case, as the video is better quality and the things to look for are clearer to me now. But it's still not going to be done quickly.

Whatever else one might say or think about Mike Collins, he has shown perseverance in this quest far beyond almost all the rest of us.

The Global Big Picture

2009-11-05T20:27:00.000-08:00

Larger implications

The most important part of our Tennessee experiences, in terms of wider relevance, can be summarized in one question:

What does it mean that we have perfect Campephilus-style double knocks in unremarkable second-growth forests at Moss Island?

First, a significant point about the continental-scale phenomenon. Other than a few seconds of bad video, Arkansas does not have anything more than other places. This becomes especially apparent when you allow for the vastly greater effort that has been expended in Arkansas than anywhere else. The best recent sightings have actually come from Florida, not Arkansas. The rate of "brief glimpses," "possible double knock detections" and other soft evidence per unit effort does not appear to be especially great there. So, subtract one extremely fortuitous video, and Arkansas looks pretty much the same as everywhere else.

There is a fundamental divide between the various projects on basic philosophy. The Cornell-led programs use a model that is tried and true for finding rare birds: determine habitat requirements, identify suitable habitat, and search those areas. This model is widely employed both by casual birders and scientific researchers. However, its suitability rests absolutely on the correctness of your habitat requirement information. If you make a misinterpretation there, you will be concentrating your effort in the wrong places and your search will be highly inefficient. Imagine, for example, if you searched for Bachman's Sparrows in Tennessee and Kentucky in open, mature pine woodlands, based on their habitat use in Georgia and South Carolina. You would miss the species entirely. In the northern areas they use recent clearcuts that have been scraped and burned, military live ammunition bombing ranges, and other habitats that look not one bit like the wiregrass savannahs they love so much farther south. Now, in this case, of course, we know how the habitat use varies over space and do know how to find the bird in the north or the south.

But, is this true for the Ivorybill? Do we really know how they would live in 2009 based on how they lived in 1939 or 1869? I would suggest we do not. The landscape has changed enormously during the last 100 years. Many bird species have adjusted their habitat use substantially over this interval. Is Tanner a good guide to where we should search now? Maybe, maybe not. The point is, we don't actually know.

How does this relate to Moss Island? By Cornell standards, our habitat is unsuitable. Hence, our encounters are largely dismissed out of hand. By doing so, the Cornell approach has painted themselves into a rather nasty corner. The logic is simple. To all appearances, we have Campephilus-like double knocks that are at least as good as what has been heard in the "core habitat" such as Big Woods and Congaree. If one claims that in "core habitat" these represent evidence for the possible presence of Ivorybills, but in "marginal" or "unsuitable" habitat they provide no evidence for the possible presence of Ivorybills, one has committed a logical no-no of the first magnitude. If the same sounds come from places where you have concluded that Ivorybills are not going to be, then you should conclude that these sounds have no relevance to Ivorybills anywhere. Conversely, if you feel these sounds are evidence of the possible presence of Ivorybills in South Carolina or Arkansas, then you must also accept that they would be evidence of the same in Tennessee, Illinois, Mississippi, Florida, Louisiana, and Texas. You can't have it both ways.

Anyone who seriously considers that Ivorybills might still persist, and that double knocks and other soft evidence have a relevance to indicating their possible presence, should accept that the evidence in total suggests their habitat requirements might be broader than has been assumed by Cornell et al. I'm not suggesting they will nest in fragmented second growth, or even use it as a full-time habitat; but there are ample indications that if these sort of encounters mean anything anywhere then the birds indeed are using fragmented "marginal" habitats for at least parts of their life history. These habitats are hugely more extensive than the "core" habitats, hence this possibility raises all sorts of further hypothetical possibilities for the natural history, survival, and conservation of the species, all of them positive. In the alternative philosophy to Cornell's, you search where you have learned of rumors, whispers, or credible declarations that something of interest might have been seen or heard there. This of course requires a lot of judgement, and eventually everyone will draw the line somewhere; I'd not put much stock in reports from western Kansas, for example -- although good double knocks in Nebraska or Vermont would settle a lot about what they might mean in Arkansas! But until and unless we actually find some reproducible birds and determine what their 21st Century habitat use patterns really are, minds should be kept open.

You will not get anyone involved in the Tennessee project to state that we have established the presence of an Ivory-billed Woodpecker anywhere in Tennessee as a statistical or scientific certainty. None of us has put an Ivorybill on his or her life list. However, if you asked us off the record for our own personal unscientific feelings, I think you would hear several confessions that indeed, some of us do strongly suspect that there has been at least one of these critters tormenting and taunting us in the delta woods for the last several years. Which means we also think that all that follows from this about habitat, behavior, distribution, etc. should be given serious consideration. Interconnected mosaics of fragmented second growth bottomland forest should be included within the spectrum of possible habitats for the species.

But, this is all still unproven, much like string theory and supersymmetry. The physicists need a visual on the Higgs Boson, we need a visual on the Mystery Double Knocker. Both groups have been waiting for years, and wait still. All remains in limbo in meantime.

My final post in this series next Tuesday will give my own thoughts about what might be done now, with the money drying up and the big questions still unresolved.

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The Local Big Picture

2009-11-02T21:00:00.000-08:00

Overview of Moss Island

All told in 2008 and 2009 we had about 30 different birders spend some time at Moss Island including our crew; 14 birders put in more than two days in the field (not including the local TWRA staff who have routine buisiness on the WMA): The core crew of me, Bob, Scott, and Melinda; Dave Pereksta, Marty Piorkowski and three Cornell volunteers; Alan Mueller and four of the Cornell full-time field staff. Collectively there were nine non-controversial double knock encounters and three controversial ones, along with at least three “brief glimpse” sightings and one or two uncertain “kent” encounters. Total effort hasn't been tabulated precisely, but is probably on the order of 1000-2000 person-hours.

There is an interesting pattern I had not noticed until recently: In each case, the “lower level” encounters (glimpses and kenting) occured within a day of a double knock encounter within the same area. Scott's glimpse and possible vocalization actually occurred in immediate association with his first double knock, Dave's 2008 glimpse was the evening before and about 300m away from the controversial double knock of 3/21/08, Alan Trently's glimpse happened about 7 or 8 hours before and about 500m south of my double knock series on 2/24/09, and my kentings were heard the day before and about 700m away from the spot from which I believe the controversial 3/18/09 double knock series emanated. Yet more circumstantial and insubstantial evidence, of course, but considering that the majority of our field days yielded nothing suspicious these clusters do raise the eyebrows a bit.

Just for fun, let's assume the MIMDKWFTII actually is a real bird, and is not a Pileated. We'll assume that the double knock is its characteristic display, not an abberation. What does the pattern of our detections reveal about this critter? First, it seems clear that though it does repeatedly visit the areas around the lakes in eastern Moss Island, it is not in full time residence there. It seems very unlikely a real diurnal bird could be so hard to find unless it was just not there most of the time. So we appear to have a bird with a large home range, only a portion of which extends into the eastern parts of the WMA -- interestingly mostly within 1000m of the Obion River corridor. It might potentally use the riparian corridors, several of which come together just southeast of our “hot zone,” to move between forest fragments. The bird does seem to sometimes spend the night at Moss Island, but perhaps not in the same place each time. One double knock near sunset, and one series just before sunrise, on different dates (actually, in different years) and in different locations suggest this.

As for behavior, the bird moves a LOT. Going in the afternoon to where it was this morning, or even just a short while before, does not turn it up. It also does not seem to like to cross the lakes. Many hours have been spent on and around Rhodes Lake without the bird ever revealing itself in the open. All the encounters in the immediate vicinity of the lake have been on the east side or to the south beyond the end of the lake; the double knocks have never been heard from the west. Encounters have happened farther west, but never heard from the lake in that direction. Finally while it may be shy of the lake, it is not actually particularly worried about people. The “hot zone” is also the part of the WMA that gets the heaviest use by hunters and fishermen. That squirrel hunter was standing only 100 or 200m from it, with two fairly large dogs, and the bird did not even flee in reaction to the gunshot. No, instead it sat still and double knocked repeatedly from the same spot. Sheesh, I heard the damn thing while sitting IN MY TRUCK parked on a public road. So the difficulties in spotting this bird seem to be a function of: mobility (doesn't stay still very long), large home range (wherever you are, it is usually somewhere else), and aversion to open spaces or even edges. It doesn't actually appear to be shy or skittish, just hyperactive, fast, and stuck like glue to the forest interior.

As an interesting note... most of these features were (are?) evidently typical behavior for an Ivory-billed Woodpecker -- more insubstantial circumstantial evidence. The one exception is the apparent utilization of fragmented forest habitat connected by narrow corridors of several miles in length. As I have written before, if Ivorybills never learned this trick, then there is no way they survived the 20th Century. So regardless of whether this was characteristic of 19th Century Ivorybills, it must be typical for 21st Century Ivorybills or there will not be any of them to look for.

Now for a bit more about the double-knocking behavior of the Mystery Double Knocker. As I mentioned before, its knocking is concentrated in the first three hours and the last two hours of daylight, and from late February until very early April. Given what appears to be the large home range and high mobility, it is hard to actually know if it really only double knocks infrequently, or if it just moves so much between performances that any given observer will not hear it more than once a day. On the one occasion when we had 12-18 people on site for two days, there were three possible encounters, two of them from different locales separated about 500m and 65 minutes. This might argue more for the problem being that the creature is alway on the move rather than its being unnaturally quiet. It does at times appear to react to loud banging sounds by double knocking; as it did this both in response to a gunshot and the double knock simulator it raises the question of whether the apparent "response" to the simulator might in fact just be a non-specific "reaction" to a general loud noise not actually recognized as a "double knock." We might do just as well by simply shooting a .22 at the top of every hour.

Perhaps to contradict myself where I stated that the hypothetical bird is usually not at Moss Island, I can play some numbers games to make guesses as to what fraction of its time it does spend there. First, working in orders of magnitude, we had a "detection" about every 100 hours. Using a general rule of thumb I find useful for many landbirds, 1 detection per hour corresponds roughly to 10 birds per square kilometer. So this detection rate would mean 1 bird per 10 km², and since we are not hypothesizing more than 1 bird this would suggest a 10 km² home range for this critter. Our "hot zone" covers about 2 km², so this gives us a very very rough estimate that the bird would be in the hot zone about 20% of the time. Where is it the other 80%? Who knows? It's still only a hypothetical bird anyway. Just to be intriguing, the hot zone covers about 20% of the forests at Moss Island, so it conceivably *could* be a full-time resident there and the apparent hot zone could still be just a statistical fluke. Or it might spend 80% of its time farther north or south along the Obion - Forked Deer riparian complex, where there are other sizable forest fragments within a few miles.

Something that might argue for a larger percentage of time spent in the hot zone is this simple observation that I had overlooked before: On days when we had 4 or more people in the field, we had a possible detection more than half the time. And again, over the two days when we had 12-18 people in the field, we totaled three possible detections. That pattern might suggest that in fact the hypothetical bird is in the hot zone full-time, or at least visits the hot zone for a while on most days. This scenario would require the bird to be significantly quieter than the average woodland bird to explain the low detection rate per observer.

These are all just games with numbers, patterns, and ideas. We of course do not have any direct evidence as to the identity of our Mystery Double Knocker. None of our sightings are remotely close to "good," and no one anywhere in North America has yet actually identified the source of these double knocks. No quantity of circumstantial patterns, hypothetical scenarios, deduction and inference can ever make an Ivory-billed Woodpecker out of mere noises and glimpses. Whatever our own personal suspicions and hopes might be, we understand perfectly well that we have not "gotten the bird."

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The Mystery Remains

2009-10-29T20:02:00.000-07:00

And the answer is...?

As of today (October 29, 2009), there have been no more encounters with the MIMDKWFTII. I've only made a few visits since June, and am probably done for 2009 as there's no money and not much free time in the near future. We made no real progress on the overall goal: Determine WTF the MIMDK is.

I do come away from the 2009 season, however, firmly convinced that the Mystery Double Knocker is a real and coherent phenomenon, not just an agglomeration of assorted misinterpreted and misconstrued unrelated ordinary occurences. Out of the whole 20 months I have been involved in this project, one or two minutes on one day haunt me the most. It was that afternoon of February 24, 2009, as the rain was ending and the grizzled squirrel hunter across the lake shot his supper. The string of double knocks that followed were utterly clear, perfect, and undeniable. Unlike my first encounter, I knew exactly what I was listening for, and what I was hearing. I was all alone, the rest of the crew having bailed because of the weather, sitting there by myself in the drizzly late afternoon gray. If my first encounter in 2008 was the Black Swan flying across the sun, this one was the Black Swan sitting on the hood of my truck. No denying its existence, no hope of talking myself out of this one. And, I knew the damn thing was just gonna fly off and disappear again.

As a loose end from my last post, some might wonder why I spent all this time analyzing my 3/18/09 recording when I expressed such strong objections to robobirders in an earlier post. Thing is, a real "meat birder" holding a video camera is not a robobirder. All that additional information that is lacking in robodata is present in the birder-videocam combo: context, apparent distance and direction, subjective impressions of quality, loudness, etc. The digital data and the analog experience are able to complement each other, without either making the other obsolete. But in reality, I think at this point in the Tennessee project the desire for "objective" documentation has as much to do with peer pressure than anything else. We have no doubt amongst ourselves about the reality and validity of the double knock phenomenon at Moss Island.

But what about all the alternative explanations for the double knocks? As far as the misinterpretation of ordinary sounds (e.g. gunshots, boat clunks, off-site mechanical sounds), in spite of how we sometimes seem to be viewed by northeasterners and west coast types, we are actually a pretty skilled, experienced, and discriminating crew. We take great care to rule these things out, and have clearly noted these double knocks as being something consistent and unusual. The various non-biological explanations also don't work with the spatial, seasonal, and diurnal pattern we have seen. Weather, construction, etc. aren't most active in the first three hours and last two hours of the day, they don't ramp up in late February and quiet down again around the end of March, and they don't cluster within the woods in the Rhodes-Hushpuckett Lakes corridor. No, the only thing that fits this is a biological source; specifically a mobile diurnal one. In other words, a bird.

What about duck wingtip collisions? Sorry, those may be able to confuse a robobirder, but they don't cut it as an explanation for the live sounds. They are an especially poor match for the double knocks that occur in series, repeatedly from the exact same direction; nor do they account for the freakishly intense loudness of the double knocks when heard from distances of about 200m or less. Really, there's only one option. It has to be a woodpecker -- a big one. Nothing else is properly equipped.

Here we come to the only alternative explanation that makes the cut: Could the Mystery Double Knocker be nothing more than a Pileated Woodpecker? Pileateds are certainly capable of making loud noises with their peckers; indeed they seem quite fond of this sort of thing, especially in late winter and early spring. They are also extremely common at Moss Island and in most other coastal plain bottomland forests in the southeastern U.S. However, no one has ever documented a Pileated making these dead-ringer-for-Campehilus double knocks; no one has actually documented a Pileated making any double knocks that are not embedded within an abundance of normal Pileated sounds. But, no one has yet specifically documented ANYTHING north of Mexico making these dead-ringer-for-Campephilus double knocks in about 70 years. Large woodpeckers have been glimpsed fleeing the scene of the (double knock) crime, but have not been seen well enough to definitely identify as Pileated or not-Pileated. It's not just the Moss Island Mystery Double Knocker, it's the North American Mystery Double Knocker.

But why not just claim Occam's Razor and call it a Pileated? Well, until someone actually sees something else making the sound, it can't be entirely ruled out. However, a lot of things don't fit. First, Pileateds are common and widespread in much of North America, not just the coastal plain bottomlands. Yet the phenomenally loud double knock has never been identified or described as part of their repertoire anywhere, by anyone. Perhaps it is an unusual display, used only rarely, and therefore only likely to be heard where they are especially abundant. Or, perhaps it is only a small percentage of individuals that engage in this display, which might also explain the spatial clustering in “hot zones.” Several things argue against these ideas. First, Pileateds are more common in bottomland hardwoods than in other forest habitats, but only by a factor of like 3-5, not by orders of magnitude. I live surrounded by hill-n-holler upland hardwood forests in middle Tennessee, where I see and hear Pileateds many times every day. Many other experienced birders live in similar proximity to the species. I've yet to hear any of these double knocks at home, where I spend far more time than I do at Moss Island. Even with all the publicity and skepticism surrounding double knocks in recent years, no one has turned up data showing any of these tens of thousands of backyard Pileateds making this sound. Believe me, if one of these things went off in your backyard, you WOULD notice! As for the “hot zones” being caused by individual aberrant Pileateds, they actually tend to be bigger than the typical home range of a Pileated in these densely-packed habitats, so you'd need multiple neighboring birds that posessed this aberrant behavior to explain the phenomenon this way. Anyway, woodpecker drums are pretty hard-wired, fixed, inborn display patterns. They're not subject to learning and they hardly vary between individuals or circumstances. It seems very unlikely there would be a distinctive, conspicuous, yet undescribed Pileated display still lurking out in the woods.

If I were in a court of law right now I'd probably be raked over the coals at this point for having produced nothing but circumstantial evidence. It's true, that's all I got, ain't nuthin' else. Until someone SEES the f'ing thing we will not really know. It's all Just So Stories in the meantime. I'm not going to commit the sin I have chastized others for and say “I don't know what it is, but I know it isn't a Pileated.” I don't think it is a Pileated, but I really just plain don't know what it is.

There only seem to be two options, however.

In the rest of my "wrap up" posts I'll talk about some of the larger implications of all this, speculate wildly about woodpeckers, and give opinions about what we should do from here onward.

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Bass Notes

2009-10-26T11:06:00.000-07:00

Singing trees, not singing fish

While I was continuing to get skunked at Moss Island, at least on the double knocker front, "Jacob" had been circulating my 3/18 double knock recording a bit amongst other interested people. I did not expect much response, as the big projects seemed to have dismissed Tennessee a year or more before. However, in June one of the Cornell PIs did have comments, and there was a bit of an e-mail conference between him and us. His initial response was two fold: very impressive double knocks, and because of the 10 second spacing almost surely just the simulations. There was some miscommunication between Cornell and Tennessee about the particulars of the simulations and timings, but even after this was sorted out the Cornellian remained convinced that mistiming, miscounting, and anomalous sound propagation were more likely than an actual response to the double knocker. He commented that, "a response pattern of just three double knocks spaced 10 s apart is unlikely for Campephilus." My observation in February of what was essentially this exact thing (three double knocks in rapid series) in response to a gunshot appeared to be given no significance. Worthy of note, we were not operating from a presumption of Ivorybillness and did not dismiss data because it did not match a priori notions of how an Ivorybill should behave. If we have Campephilus-like (actually, Campephilus-identical) double knocks at Moss Island, that fact is of great significance to the Ivorybill quest regardless of whether or not they truly are from an actual Campephilus. I'll have more to say on that in my concluding posts in this series. In the end he concluded that the sounds I recorded were "quite obviously something else than an Ivory-billed Woodpecker." My closing response to this was, "'Obvious' is a judgement. There are many rational, well-educated people who consider it obvious that the human mind was intelligently designed, that the bird in the Luneau video is a normal Pileated Woodpecker, and that double knocks are caused by duck wingtip collisions."

Beyond these immediate discussions, though, we also talked about what sorts of responses to the double knock simulator might be expected based on what has been seen in other Campephilus species. Much remains unanswered, but doesn't it seem likely that there would be wide variability between species, times of year, and local circumstances? Imagine if you tried to predict the behavior of a Lincoln's Sparrow on the wintering grounds based on the behavior of the congeneric Song Sparrow on the nesting grounds. You would get some broad generalities right, but would be wildly in error on many important particulars.

There is one well-publicized example of the behavior of a pair of Campephilus woodpeckers in response to simulated double knocks: David Attenborough's Magellanic Woodpeckers. Bear in mind, though, that this is a nature documentary, not a piece of raw scientific data. What we see in the final video is very likely a greatly edited abstraction from a large amount of footage. Who knows how many attempts were needed before this worked, if Attenborough's little tapping on the tree with two small rocks is the only attractant they actually used, whether they might have been standing 10 meters away from the birds' nest tree, if every shot is even of the same pair of woodpeckers, etc.? This is primarily entertainment, not scientific documentation. Still, though, it is the best footage of double-knocking Campephilus that I have seen anywhere.

I have wondered ever since I first shot the 3/18 video if there is a way to determine whether the double knocks I recorded are real or simulated based purely on the properties of the sounds themselves, without involving matters of timing, location, etc. To the ear the simulator can be a good approximation to the real sound, but it is not identical. Spectrographically there are some notable and consistent differences, which I alluded to in the previous post. I already posted one sonogram of the sound of the simulator at close range; here are two more along with video clips so you can hear also. As always, click the sonogram to see a larger version:

April 9:

August 21:

And here are samples of double knocks from the same simulator recorded from increasing distances, from August 21-22:

Note that to improve legibility, I boosted the gain by 100% on the middle three and by 200% on the last one, hence there is a lot more drop in loudness than it appears. The final sample, from 600m, was recorded at dawn; the others were at midday. It shows very well the greatly improved sound propagation in the dawn stillness; remember though that it is still less than 1/3rd of the distance that I was from Scott on the morning of 3/18. Looking at the whole sequence, you see the loss of the high frequencies, the blurring out of the sharpness, especially in the second knock and at midday, and the persistence of the long trailing gunshot-like echo at lower frequencies, regardless of time of day.

For comparison, here are two examples of real double knocks. First, a Powerful Woodpecker from the Macaulay Library of the Cornell Laboratory of Ornithology, catalog number 84098:

Next, here are sample double knocks from David Attenborough's Magellanic Woodpeckers (I hope the BBC, who seem to be checking my blog regularly, do not object to this use of a tiny sample of their footage. It would seem like fair use to me):

The most obvious differences are twofold:

A. The simulations have more high-frequency sound than the real double knocks.

B. The simulations show a more pronounced trailing echo than the real thing, looking almost like little gunshots with their broad rightward smear.

The real sounds are variable in their frequency distributions, especially on the low range. The examples that show the strongest base notes are the ones by the male Magellanic when he appears to be rapping close to a cavity, presumably near a void in the tree truck. This deep base is what gives some of the knocks their hollow, resonant quality.

Look more closely at the basso profundo on the Magellanic double knocks. Notice how the vertical line marking each knock bends to the right towards the bottom. There is a delay of a few milliseconds in these base tones as compared to the higher frequencies. In the Magellanic knock with the strongest base, it looks like this delay is actually greatest not in the deepest tones, but a bit above them; it's a bowing out, not a simple rightward bend. On the Powerful sonogram, the basso profundo is much less forte. But in the clearly visible faint tails at the bottom of the knocks, we see a distinct rightward bend as well.

I should say here that I am a hack when it comes to bioacoustics. Sure I have a Ph.D., but it is in Ecology, not Physics, Acoustics, or even Music. My formal training in acoustics would have been nothing beyond college physics about 28 years ago. So I am no expert here. But I'm not a total dope, either. It seems to me that this rightward bowing on the base of the sonogram, indicating a delay in the production of the tones in the frequency range of a few hundred Hz, is likely a property of the resonance of tree trunks. I expect it is this brief delay that especially gives the real knocks their sonorous, resonant quality.

Now, look back at the simulations. They do not show this feature. The initiation of the sound is at the same instant at all frequencies, making a crisp straight vertical line on the sonogram. Whatever the resonance properties of a real tree are that produce this effect, the simulator appears to lack them. Again, I'd hypothesize that the lack of this feature is what makes the simulations sound subjectively less resonant to the ear. There is no lack of the basso profundo tones in the simulated double knocks; they just happen at the exact same instant as the higher tones and thus to the ear are absorbed within the one big sharp "whack." I would propose to add a third distinguishing feature that can potentially differentiate simulations from the real thing:

C. The simulations lack the rightward bend of the sonogram at low frequencies; all frequencies of sound are produced at the same time.

As far as utility in the field, it varies between each feature. Item A, the excess of high frequencies, will fade out rapidly in a forest so it is probably of no real value. Item B, the trailing echos, certainly might be useful. In the data I posted both here and in the previous post showing the simulations at different distances, this only becomes more prominent with attenuation, as the whole sonogram dissolves into mush. Unfortunately I do not have any recordings of known real double knocks at great distance for comparison. Item C, the rightward bending base of the sonogram, might well survive over distance. As the speed of sound in air is largely independent of frequency, this feature (straight versus bent) should be preserved for as long as the sound remains crisp enough to give a good spectrographic image. It's also worth noting that this feature might be useful for separating "real" double knocks from other sounds, such as duck wingtip collisions, construction or vehicle noises, etc.

Finally, to the Tennessee sounds from March 18th one more time. Here is the clearest one, number 3 (click to enlarge):

As would be expected in either case, the high frequencies are gone. In the base tones that remain, I see rightward bowing. In fact it looks almost exactly like the shape of the Magellanic double knock at the same frequency range. There is also not a trace of the trailing echo, or any other smearing. So for the two criteria that might be meaningful in the field at a distance, this one scores as "real" on both.

Here are the other two 3/18 double knocks, along with the audio/video again:

The first knock of #1 is fairly clear; it looks bent to me. The final note of this double knock, plus both notes of double knock #2 are very faint. Still, the faint lines do seem to show a bend.

Score for this round:

Simulations: 0
Real thing: 2

Once again, this still only indicates that the sound is not the simulator and is something else rapping on wood making a sound very much like a Campephilus double knock. As always, this does not in itself prove the presence of a real Campephilus woodpecker at the site. But it again supports the idea that the Moss Island Mystery Double Knocker is a real and coherent phenomenon, not just a random assortment of ordinary sounds being misinterpreted.

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