Ivory-billed Woodpecker is extinct.

Ivory-billed Woodpecker. John James Audubon painting.

by Gunnar on February 2, 2012 · 0 comments

in Birding News

Ivory-billed Woodpecker is extinct, say two teams of researchers

Here is a very interesting article in Field of View, Birdwatching’s blog, about two recent publications regarding the continued exististance of Ivory-billed Woodpecker.  The two parties came to the same conclusion: Ivory-billed Woodpecker is extinct.

Here are some excerpts from the article.

The first team, led by biologist Nicholas Gotelli of the University of Vermont, studied 239 Ivory-bill specimens collected from 1853 to 1932. The researchers concluded that the chance that the species persists today is 0.0064 percent. Said another way, the odds of finding a living Ivory-bill are less than 1 in 15,625.

Gotelli and his colleagues also considered whether additional searches would improve the probability of discovering the Ivory-bill. They evaluated evidence from searches conducted by the Cornell Lab of Ornithology in 2006-07 “at four sites deemed to be among the most promising for relictual populations” of the bird: the Congaree River in South Carolina; the Choctawhatchee River in Florida; the Pearl River in Louisiana and Mississippi; and the Pascagoula River in Mississippi.

The question is when to stop searchng. Gotelli and his team came up with a formula.

“A simple, empirical stopping rule is to stop searching when each observed species is represented by at least two individuals,” Gotelli writes. The formula means that further searches at the Congaree River site are not warranted because the Cornell team reported observing more than 15,000 birds, and each of the 56 species it reported were found at least twice.”

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A second team of investigators, led by Andrew Solow, a senior scientist at the Woods Hole Oceanographic Institution, analyzed 29 so-called uncertain sightings of the species since 1946, including headline-generating reports from the Pearl River in 1999, Cache River NWR in Arkansas in 2004 and 2005, and the Choctawhatchee River in 2005. Solow’s paper describes a statistical method that “is the first to treat uncertain sightings in a formal way, neither simply excluding them nor simply treating them as valid.” Solow’s group concludes that “the Ivory-billed Woodpecker is extinct,” but the researchers don’t provide an estimate for when extinction occurred.

Read the rest of the article in Field of View, which also features opinions from well-known Ivory-bill searchers, Jerome A. Jackson and Bobby Harrison.  Check it out.

Top image: Ivory-billed Woodpecker. John James Audubon painting.

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