Again About the Ivory-billed Woodpecker

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In the fall of 2021 the U.S. Fish and Wildlife Service declared the Ivory-billed Woodpecker extinct as there have been no reliable sightings of the bird since 1944. But individuals and groups have occasionally asserted that they have seen an individual or two deep down in the forests of Louisiana. The latest declaration is from a team of researchers who used cameras and drones over a period of three years to capture photos of the bird. The research has not been peer-reviewed, so I don’t know what the ornithological community has to say about it yet.

Although the photographic evidence is poor, being long distance and out of focus, some photos do seem to show the white saddle mark on the back of the Ivory-bill. I am doubtful, though, for a couple of reasons. First, nearly 80 years is a long time for a bird to remain hidden; it seems unlikely that no one would have gotten a decent photo over that time. Second, releasing this kind of information to the public without a peer review by other ornithologists is suspicious and reminds me of the cold fusion fiasco some years ago. And third, what makes it more unlikely is the examination of the population size that would have to exist for the Ivory-bill to persist all these years.

File:Ivory-billed Woodpecker by Jerry A. Payne.jpg - Wikimedia Commons

Without getting into all the math and statistics that were used to come up with these figures, one rule of thumb is that for a bird population to remain viable, there would have to be a minimum of 50 birds.  This is called a genetically based minimum viable population size. You can read one study on the red-cockaded woodpecker (Picoides borealis) which determined that the species must contain 509 breeding pairs to remain viable.

Estimates of the size of the area needed for feeding by a breeding pair of Ivory-billed Woodpeckers is 6-10 square miles. That means, at a minimum population of 50 birds or 25 pairs, the birds could be scattered over 150-250 square miles. Is it likely that 25 pairs of birds scattered over this large an area could remain hidden for 80 years? And that the population remained at a minimum of 50 birds over that time?

But at an estimated life span of 15 years, it is possible that a few birds still remain from a small population that existed eight decades ago. But again, unlikely. Ivory-billed woodpeckers once inhabited forests from Florida to North Carolina and southern Illinois, and even Cuba. But during reconstruction after the Civil War, the lumber industry chopped up the southeast’s woodlands and created disconnected habitats, undermining the woodpecker’s habitats.

The Holy Grail or Lord God bird was declared endangered in 1967 but as late as 2005, scientists from Cornell University and the Nature Conservancy proclaimed they had sighted the bird in Arkansas. Turns out that the low-resolution photographs were of the similar Pileated Woodpecker, the source of virtually (or probably) all misidentifications of the Ivory-bill.

It’s rare for new bird species to be discovered. In 2020 ten new species and subspecies were found on some barely explored islands in Indonesia. That I can believe. But the Ivory-billed Woodpecker in the southeastern U.S.? I need more than fuzzy photos.

4 thoughts on “Again About the Ivory-billed Woodpecker”

  1. Pingback: Birds – Animal News Live

  2. What gets me really upset in articles like this is the brushing off by United Statians of their responsibility for SHOOTING down the Ivory billed woodpecker to extinction ! The timber industry is a convenient excuse. Yes cutting old growth forest disconnected habitat but that is far from enough to bring a bird to the brink of extinction over 3-4 large states. The reality is more analogous to the shooting down of the passenger pigeons to extinction for SPORT ! and favorite pastime in USA ! The Carolina parakeet extinction is the closest shared fate. People shot them down because 1) Colored feather were highly prized by the Victorian nobility for the manufacturing of hats 2) There was a trend with taxidermy where displaying stuffed dead animal in your home as trophy was desirable (?!) 3) United Statians literally shot living things as a pastime, not even for hunting.

    There is a repeating trend with United-Statians to evade historical responsibility at every corner, something they may have inherited from the Englanders that have a similar historical amnesia problem whenever they did something wrong.

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