Thursday, November 05, 2009

The Global Big Picture

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.

Other posts in this series:


At 11:41 PM, Anonymous David Alford said...

Regarding the DKs, do you not give any credit to the previous comment, "TRossEverett said...
Now some may say I am full of it or not experienced enough,etc. to be believed or relied upon. But if you will read my notes about my first encounter ( you can find them in one of the summary reports from Cornell. ) You will see that I watched this bird for several minutes while it was foraging around on a tree and DK'ing from 30-35 yards away." ?

At 7:44 AM, Blogger Bill Pulliam said...

He's not a birder. I learned about 40 years ago that every duck hunter and deer hunter you talk to in the deep south has a story of the time he saw an Ivorybill; usually multiple sightings. Unless some birder or wildlife professional is also involved, I don't find these reports valuable. Hunters know a lot about game, but they usually don't know much about non-game wildlife.


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