Sunday, September 17, 2006

-- Tanner Again --

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The locale where Ivory-bills will be announced at the Oct. AOU meeting was never visited by James Tanner, and one has to wonder how many other such sites his 'definitive' study completely missed, especially since he didn't have the benefit of aerial photography. Tanner's monograph on Ivory-bills is often referred to as a 3-year study, but by his own admission he only spent 21 months in the South, and a lot of that time was travelling on the road and engaging locals in conversation for information-gathering. Over 10 months alone were spent solely at the Singer Tract where all of his personal observations were made, leaving less than 11 months for a single individual to cover the entire remainder of the south -- essentially an impossibility for anyone to do today adequately, with good roads, better/lighter equipment, and far fewer key areas to explore, and truly an impossibility in Tanner's day (
indeed, he likely spent more hours in the front seat of a car on dusty, bumpy rural roads of the 1930's South than he did trampling through any actual Ivory-bill habitat outside of La.).
Tanner claimed he visited 45 locales in that time (actually, some of them were adjacent to one another, so it's debatable if they could justly be called separate locales), but only spent a week or more in about 5 of them; the rest usually got only a 1-to-4 day visit, hardly enough time for adequate exploration of large forest tracts. In the end he only observed birds at the Singer Tract (thanks to a guide who led him to them) -- statistically, not only was it a wholly inadequate sample size, it was not a random sample of IBWOs either, and of course it was never replicated -- these are rather minimal scientific requirements. While Tanner gathered some other anecdotal and occasionally more empirically-based information along the way to throw into his mix, still there was little solid basis for the generalizations and conclusions that would follow his work. As I've often said, his is a wonderful, fascinating, and astute study of a handful of birds, but a largely inadequate and incomplete study of an entire species.
It is somewhat revealing that people will try so hard to tear down the work of Cornell University in the Big Woods of Arkansas with wholly-unproven and debatable arguments, yet blithely accept the narrow findings of a single lowly grad student from 60+ years ago, and moreover assume those findings still hold today if they ever did. If searchers ever thoroughly explore all of the appropriate habitat out there no telling what they may find, while cynics busy themselves with their pre-formulated armchair analysis. In their typical manner many of them are already deriding (pre-deriding?) the evidence to be announced in Veracruz without having seen it (more good empirical technique -- this applies to some, of course not all, the skeptics). It has reached a point that some of them must quietly hope and wish that the Ivory-bill is extinct in order to save face (their claims to the contrary are disingenuous and whenever IBWOs are confirmed, it will be fun to watch their faux excitement). It is a point, needless to say, we ought never have reached.
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