Thursday, October 01, 2009

More Troups

Call up the reserves

February 17, 2009

Other commitments kept me from being able to overnight at Moss Island for another week or so, but I managed another day trip on this date. I spent a half day and change in the Rhodes Lake area; Scott was on site as well working around Forked Lake. Whatever Beulah had seen the previous week, it was our only lead so far this year and it had been seen flying from Forked Lake towards Rhodes Lake. It was another grey and quiet winter day. The ornithological high note was a full set of Eagles over Rhodes Lake:The camouflaged creature in the second half of the clip is Scott, of course.

February 23, 2009

For a change, it was a mostly sunny day. Dave Pereksta was due to arrive around noon, planning on 2 or 3 weeks of work, entirely on his own vacation time and personal expense. He had been on the road for a week or so already, making a few birding stopovers on the way from Ventura County to Dyer County. I arrived early and covered the southwest woods in the morning, encountering a strange artifact deposited by floodwaters, then returned to the barn to rendezvous with Scott and Dave.

On my arrival at the barn, Beulah accosted me excitedly. She'd had another encounter. The previous Friday (2/20/09) she had been hiking the ATV trail that goes south from the turnaround, the trail that runs west of Hushpuckett Lake and from which I had heard my first double knock 49 weeks earlier. She had been about 100m from the spot of my first DK-hearing when she heard what she said sounded like somebody whacking a tree with a baseball bat extremely hard, twice in rapid succession. She didn't have a real distance estimate, just saying it had been quite close and had nearly made her jump out of her skin. She wasn't able to see the source of the sound.

As in so many cases, the description sounds good.. HOWEVER... I had described the double knock to her previously, using words and terms very similar to the ones she used when she described what she had heard to me. Still, the encounter sounded much like Scott's very first incident on February 28, 2008 that had launched the whole show, except lacking the glimpse of a fleeing large bird.

As before, though, whatever it was, we didn't have any other leads. After Dave arrived we divided up and headed back to the old "hot zone;" I headed down that same ATV trail again. About halfway down the trail I had what we have come to call a "Luneau moment." Ahead of me through the understory, I caught a glimpse of a fleeing dark bird with brilliant white on the hind portions of its wings. The intervening brush made judging size and distance tricky, but it somehow gave an impression of being a large bird. As I continued in that direction, I found nothing but an active assembly of Red-headed Woodpeckers. Reclassify that "impression" of being a large bird as more likely an "illusion" of being a large bird, and ticky that one as a Red-headed with grand aspirations.

At sunset we reconoitered at Rhodes Lake to compare notes and discuss the plan for tomorrow. The video clips from this day ("Luneau moment" not included, cam did not get it):

February 24, 2009

We had initially had ambitions for a moderately large-scale effort on this date, but most of our potential recruits were unable to make it, and even Melinda was not available. In the end we did marshall a team of four: me, Scott, Dave, and Allan Trently, a birder, botanist, and biologist with the Tennessee Department of Environment and Conservation based in west Tennessee. Between the four of us we represented two State and one Federal agency, though Dave was here on personal time not in his official capacity with the FWS.

After a dawn assembly at the barn, we split up. We were again focusing on the old "hot zone," primarily because we wanted to remain fairly close to each other. I took the ATV trail again, hiking about halfway down it and sitting quietly in the damp gray cold (about 1 or 2 degrees C). The birds were moderately active, but I heard no clarinets or baseball bats whacking trees, and saw no woodpeckers with white secondaries other than dozens of Red-headeds. The noontime rendezvous happened at the west end of Rhodes Lake where there are a primitive campsite and a gravel boat ramp. For the most part we had a whole lot of the same to report; Allan, however, had sort of seen something kind of interesting. He had hiked south from the trail on the east side of the Rhodes Lake sill, in the isthmus between Willow Flat and the shrub swamp below the sill. He had his own "Luneau moment," a large woodpecker seen flying off briefly that appeared as though it might have had white in un-Pileated places. He was not worked up about it, just matter-of-factly saying it might have been interesting but he didn't get much of a look at it.

Once again, it might not have been much but it was all we had. We deployed ourselves spaced about 50m apart and hiked slowly south through this same patch of woods. After about 90 minutes, with the gray skies getting grayer and more threatening, and little to show for our efforts, we turned around and repeated the exercise northwards. On the return I crossed paths with a grizzled squirrel hunter and his two dogs. The TWRA truck at the trailhead obviously made him nervous, and he immediately began to show me his credentials and his weapon to prove he was in full compliance with the game laws. I told him I didn't give a damn, I wasn't involved in enforcement, we were just doing bird surveys. We chatted for a bit (I never mentioned woodpeckers, crested or not), talked about his dogs, and continued in our opposite directions.

Videos from the the morning sit, lunchtime conference, and afternoon hike:

Back at the trailhead, Allan had to head home. Light rain was beginning as the three of us who remained decided to just spread out along the lakeshore roadside and listen. Dave and Scott took the south/east end, I drove to the west end and pulled into the boat ramp. The rain began to fall steadily, and it was not long before Scott and Dave drove past me, calling it a day and heading back to camp. I stuck it out, sitting in my truck watching the rain fall.

Around 4:30 or so, the rain began to slacken enough that I could roll my truck windows down a bit, then open the doors for better listening. About 4:45 I heard a single shot from a .22 rifle ring out from across the lake and down at the far end. Maybe the squirrel hunter had bagged his supper? Not even a minute later, as I was pondering if the rain had let up enough to get out of the truck, another sound came from across the lake just a little to the left of the direction of the gunshot:


Other posts in this series:


At 11:40 PM, Blogger Unknown said...

4:46 is about an hour before sunset on Feb. 24th. This bird may have DKed (I'll assume that's what it was) because of the hunter disturbance, but any thoughts on trying to find roost holes (or a roosting area) by listening for DKs around sunrise/sunset?

My own view on this whole thing is that once you get *The Photo*, then what? How do you study and survey a bird with the rare fly-by? We need to locate roost holes, and IMO the only way to do that is acoustically, with the hope the bird is inclined to DK when entering or exiting a roost hole.

Tanner noted that a mated pair will kent call in the morning. I can't remember the source, but I recall someone else observed or believed that they will sometimes DK in the evenings/morning near the roost holes as well.

I looked at the times of Dan Mennill's recordings in Florida with Geoff Hill. There was a slight bias for DKs within an hour of sunrise and sunset. Some were actually before sunrise (none were after sunset). Maybe that there's a bias isn't meaningful, but a bird that DKs within an hour of sunrise is probably a lot closer to its roost hole that one that does it at noon.

At 5:02 AM, Blogger Bill Pulliam said...

I'll talk about all these things more in upcoming posts. Overall most of our DKs have been heard in the first three hours and the last two hours of daylight. The earliest was 4 minutes before sunrise, the latest was 20 minutes before sunset.

If it is ever determined that these DKs are indeed from Ivorybills, then I think we survey the bird just by listening for DKs. It's the only data that are able to be acquired with reasonable amounts of effort and resources. I don't think we need to know the locations of roost holes themselves if we know the general patterns of spatial and seasonal occurrence and habitat utilization.

At 9:43 AM, Blogger fangsheath said...

My own study of the putative DK's posted on Dr. Mennill's web site indicated a strong peak in early morning and a sharper peak in late afternoon. Both peaks were sharper than the corresponding ones for putative kents, although these also dropped off toward mid-day. I agree that DK's have much potential to provide a proxy for visual observation in estimating population densities. But until clear imagery is obtained, such studies will simply be written off as ghost-hunting.

Eventually an active nest will be found and this will move us forward by leaps and bounds. My guess is that well before this happens, an active roost will be found, and it will yield the first clear ivory-bill images in decades.

At 3:47 PM, Blogger Unknown said...

This is what I got out of Mennill's data, using the times available from his website and then adjusting for sunrise/sunset on whatever date the recording was made. I tried to only count DK "events", not every DK in a series. I excluded multiples DK if they occurred within a few minutes.

Before sunrise: (3)
Sunrise to +1 hour: (7)
Sunrise+1 to +2 hour: (6)
Midday per hour average: (5.5)
Sunset-2 to -1 hour: (9)
Sunset-1 to sunset: (8)
After sunset: (0)

I'm not sure how meaningful this is (even if we were sure all of Mennill's DKs were actual DKs). We would need to know what causes the ivory-bill to DK in the first place. What's interesting to me, however, is whether they do it near their roost holes, such a call to a mate. That there are recordings very early and very late in the day is encouraging.

At 7:03 PM, Blogger Unknown said...

I want to follow-up on my own post because I remembered something that wasn't encouraging about Mennill's data when I looked at it before. There doesn't seem to be a meaningful pattern in the DKs, such as evidence a bird using a roost on consecutive days AND consistently DKing while near it. Either:

1. No active roost hole is within ear-shot of the equipment. (very likely).

2. The birds are not revisiting the same roosts (not likely).

3. They don't often DK near their roosts. (?)

4. Other.

At 8:40 AM, Blogger fangsheath said...

You raise some important points, I would offer the following observations for what they're worth.

I have most certainly observed pileateds emerging from their roosts and flying off without drumming or vocalizing. Last year I monitored a cavity tree with a Reconyx camera for about 6 weeks in late summer. The tree recorded a least one pileated roosting within, often two, almost daily. The days in which a least one bird did not emerge from the tree were the exception. Starting in early September, I placed a remote recording device very close to this tree, which obtained recordings daily for the next 3 months. Most days it recorded no pileated drumming. Occasionally it recorded repeated drums, obviously from a bird nearby. More often it picked up only a single drum. But most days no drumming and no vocalizing nearby.

In his study of the Cuban ivory-bill, Lamb observed a female emerging from her roost on several occasions. He stated that she would emerge, fly to a nearby tree, climb it, and within minutes fly 300-400 yards to another tree. There she would vocalize, then "leave the valley."

I would add the following observations of Tanner. Except for nesting birds, ivory-bills in the Singer Tract moved so far so fast that Tanner was unable to keep up with them. This is one reason most of his observations are on one pair of (nesting) birds. A lone ivory-bill observed by Tanner was often absent from one of its known roosts. And importantly, he found no evidence whatever of territorial disputes. These observations lead me to suggest that there is no reason for an ivory-bill, or even a pair of ivory-bills, to confine themselves to a particular roost area when not nesting. When they are in a given area, they may well favor known cavities. But particularly in the pre-nesting period, pairs may be covering large areas of forest in search of quality nest sites.

At 8:54 AM, Blogger Bill Pulliam said...

I'll have a lot of summary discussion here once I finish with the journal though the end of spring 2009. In short, however, *IF* our DKs are from Ivorybills (which remains a big if), the spatial and temporal pattern is completely consistent with what fang describes above. A bird that is highly mobile, usually not even on he site, favoring certain areas but by no means resident in them. We have attempted to track down roosts based on DKs heard shortly before sunset or immediately at sunrise with no success. These eastern fringes of Moss Island would seem to be just one occasional foraging ground within a much larger, and as yet undetermined, home range. More later...

At 4:51 PM, Blogger oncoyle said...

I'll quote this from Tanner, from the second paragraph of Chapter 11:

"The bird usually came out of its roost hole silently, and climbed to the top of of the tree where it would often sit, preen, stretch, and peck with some vigor at the limb on which it was perched. After a minute or so it would call once, then more, single kents; frequently its mate would answer and one bird would fly to and join the other."

This is what got me going down this path. It's reasonable to expect a mated pair to communicate in the morning in order to hook up, since, as Tanner observed, they will roost in different trees, sometimes hundreds of yards apart. But a single bird? Probably not a point to it.

Of course, kents are not as useful to us because they won't carry like a DK will.

Also, in the "Roosting" section of Ch. 11, I interpret Tanner's observations as ivory-bills were very much inclined to repeatedly reuse the same roost holes, though some birds more than others.


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