Bread Crumbs

Last spring, Cornell announced that the Ivory-billed Woodpecker had been refound. Last week, I shared some of my thoughts about the lack of conclusive proof provided with that announcement. News reports named Richard Prum, Mark Robbins, Jerry Jackson, David Sibley, and Kenn Kaufman as skeptics.

Yesterday, a New York Times article says that Prum and Robbins now believe that new audio evidence proves the existence of at least two Ivory-bills. Based on that article, I'm now seeing Internet postings with headlines like "Everyone agrees; there are multiple IBWOs!"

I think it's much too early to state that *everyone* agrees. For starters, are Jerry Jackson, David Sibley, and Kenn Kaufman convinced by the new audio evidence?

I think it's very interesting that Prum states that he was very skeptical of the initial Ivory-billed reports, and that he still believes that the video shows a Pileated Woodpecker. The growing message seems to be "Ok, so the video and sighting evidence wasn't very strong. But look, now we've got irrefutable audio evidence!"

I'm wondering why audio evidence is suddenly considered so very credible. On Cornell's own web site, we still see a different view of audio evidence:

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If a clear, time-stamped photograph is irrefutable evidence that the Ivory-billed Woodpecker lives, then recorded sounds of Campephilusprincipalis--and not something else that sounds almost like it--are high-tech "breadcrumbs."
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"Think of these recorded sounds--the signature double-rap of the ivory-bill or its kent call--as bread crumbs leading a camouflaged photographer to the base of the tree for that once-in-a-lifetime photo."
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Audio evidence was also mentioned in Cornell's April Science report, but it sure didn't seem definitive back then:

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Double-knock sounds strikingly similar to Campephilus display-drums were recorded on several of the ARUs...We cannot positively associate these recorded signals as belonging to ivory-billed woodpecker, however, and several seem out of context. Series of nasal calls closely resembling those recorded by A. A. Allen at the Singer Tract in 1935 were recorded at two places in the White River National Wildlife Refuge, but these may have been given by blue jays (Cyanocitta cristata, a notorious mimic).
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Ok, so 24 automatic recording units were spread over 160,000 acres, and recorded 17,000 hours of audio. How can we be sure that the key recorded sounds came from actual Ivory-bills, rather than from some combination of distant gunshots, nuthatches, other woodpeckers, people playing Ivory-bill tapes, jays mimicking people playing Ivory-bill tapes, etc?

I agree with Cornell's web page--these sounds should only be used as high-tech bread crumbs, but never as standalone proof. Cornell said they've checked out the spots where the key audio was recorded, but have so far found no Ivory-bills.

The evidence to date consists mostly of sub-optimal sightings and some bread crumbs.

Based on my reading of the publicly available evidence, here are some questions and answers:

1. Do we have a good photograph?
Answer: No

2. Has anyone seen the underwing well enough to describe it correctly?
Answer: No

3. Has anyone seen the white dorsal stripes well enough to describe them correctly?
Answer: No

4. Has anyone seen the bird well enough to describe the white neck line that ends before the bill?
Answer: No

5. Has anyone seen the bird well enough to describe the pale bill?
Answer: No

Again, the David Sibley standard for proof is "redundancy. Repeated sightings by independent observers of birds really well seen." That is not too much to ask.

I truly hope that such proof will emerge sometime soon!