Tuesday, September 06, 2005

It's all about the roost-hole

Yesterday, cyberthrush posted some thoughts about the current Ivory-bill evidence here. Both of us agree that the video is weak, and that the audio evidence is inconclusive.

We do have a major difference of opinion on the sighting evidence. Cyberthrush wrote this:
I believe the multiple sightings from experienced and credible witnesses at different times, angles, places, of a bird of striking size and features represent excellent evidence, and the likelihood of so many mis-IDs is miniscule. (In the past, multiple-credible observers were a gold standard for a rare sighting; but suddenly in today's video-infatuated world film/photography is the new 'standard.')
I think the big issue here is NOT the credibility of the observers or the sheer number of sightings; the issue is the quality of the sightings. As you may know, Sibley's standard of proof is my standard: "redundancy. Repeated sightings by independent observers of birds really well seen." The big problem with the current evidence is that we have zero cases where an Ivory-bill was really well seen. For me, a large number of low-quality sightings (ie, glimpses of large birds that appeared to have trailing white wing edges and maybe an unusual flight style) is not impressive.

In the end, I think the whole Ivory-bill controversy really boils down to one thing: finding an active roost hole. Back in the '30s and '40s, these roost holes were found many times, and high-quality evidence was gathered there. If any birds still survive today, someone will find an active roost hole, and indisputable, high-quality photographic evidence and sightings will quickly follow. It's now been 61 years since a confirmed Ivory-bill sighting in America; maybe year 62 will be our lucky one.

By the way, I believe the skeptics are actually very reasonable people. If Sibley's standard (above) is met, I will be satisfied by the proof, and I would bet that Jackson, Prum, Robbins, Kaufman, and of course Sibley would be satisfied as well. (No reasonable person today would ever want or need to see a "bloody Ivory-bill carcass", and frankly, I wish "believers" would stop making that insinuation.)