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IVORY-BILLS  LiVE???!  ...

=> THE blog devoted to news and commentary on the most iconic bird in American ornithology, the Ivory-billed Woodpecker (IBWO)... and... sometimes other schtuff.
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Sunday, October 30, 2005

 

-- Latest Audubon Magazine Article --

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The latest (Nov.) issue of Audubon Magazine includes an article discussing why the Pileated Woodpecker still thrives today while the Ivory-billed almost died out. It employs the same arguments used in the past (adaptability, diet, habitat needs) based, as all the literature is, on Tanner's work which, as I've argued before, could simply be wrong in some of its details, especially as applied to individual surviving birds instead of to the species as a whole.
The article does note that Pileateds too became rare during the 19th century but by the 1940s was making a comeback just as the Ivory-bill was being written off. The sheer original population of Pileateds, ranging over the entire east half of the US rather than just the Southeast,
may have been 100X greater than that of Ivory-bills, and easily account for its widespread survival today without resorting to any other differences. If say, 15,000 Ivory-bills were killed by hunters/collectors through the 19th century (that's just 3/week for the entire southeast) it may have decimated an already thin IBWO population, while the loss of 15,000 Pileateds may have been negligible long-term for that species.
Both the PIWO and IBWO resided in a forest plush with food -- to simply posit that the IBWO had specialized unmet dietary needs accounting for its downfall, while the PIWO (and ALL other birds of the forest) lacked such specialization is little more than a circular argument unless one can demonstrate actual physiological differences between the two species that account for such differences (some have tried to argue previously that bill size/shape differences resulted in differing needs, but this is not altogether convincing). Again, as written here previously, observations of IBWO behavior from the past can only indicate 'preferences' of those birds witnessed, and can not be assumed to be an accurate reflection of the biological survival 'needs' of the species which could be far more minimal -- I for one consume pizza and salad every week, yet in spite of any Tannerian-like conclusions one might reach, could still survive quite nicely if those choices were stripped away forever... and I don't even have wings to carry me far-and-wide in search of food.
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