.comment-link {margin-left:.6em;}

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.
-------------------------------------------------------------------------------------------------------------------



Google
 
Web ivorybills.blogspot.com

"....The truth is out there."

-- Dr. Jerome Jackson, 2002 (... & Agent Fox Mulder)

“There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.”

-- Hamlet

"All truth passes through 3 stages: First it is ridiculed. Second, it is violently opposed. Third, it is accepted as self-evident."

-- Arthur Schopenhauer






Monday, November 16, 2009

 

-- Stepping Over to the Dark Side ;-) --

-------------------------------------------------------------------------

I'm expending a lot of brain cells recently trying to understand how we could have so little firm evidence of Ivory-bills after this widespread, 4-year effort. But let me now turn it around for one post and ask the opposite question: IF the birds are long extinct how could there be so many repeated sightings over time? In a famous 'Seinfeld' scene (fans will remember) Elaine answers, "Fake, fake, fake, fake" to a question. The common refrain from skeptics to the IBWO situation is similarly going to be "mistake, mistake, mistake, mistake" (and, well, occasionally also 'fake'). But that is too simplistic; if you believe in such a long history of mistakes, how do those mistakes come about? There is only one feasible explanation that has ever made any tenuous sense to me (...and to give credit where credit is due, I believe "PCoin" was the first to propose this to me long ago... apologies, if it was someone else and my memory is lapsing!):

We know Cornell found a largely albinistic Pileated in the Big Woods (body mostly white), and additionally partial leucistic PIWOs (with small white patches somewhere on their body -- see comment clarifications) have appeared from time-to-time. The question I asked at that time, over two years ago, was, what might the parents, siblings, and offspring of such birds look like? Might there not be, somewhere in the mix, birds with intermediate amounts of white (not small patches, but not the entire body)... and among those, could there be the rare, occasional individual where the added white actually appeared as a back mantle triangle, mimicking that of the Ivory-bill? What are the chances?? Well, as many know, Noel Snyder (a thoroughly reputable, credible birder) reported just such a bird in Florida back in the 70's (I believe?); no photos, just his verbal report of a Pileated he dang near took to be an Ivory-bill, before getting a better look at the head. If there was one, how many others might there be stretched across the Southeast at any given moment, or in any given decade for that matter. And would it not be easy, in brief glimpses, to mistake them for IBWOs given the long-time emphasis on wing pattern for ID'ing these two species?

Moreover, the "PCoin" view further hypothesis (as best I recall) was that such birds, being mutations, might be less healthy, living shorter lives than their counterparts; maybe even being shunned by them as oddballs/outcasts, in turn causing them not to remain long in any given area; staying on the move. People wandering in the woods might report these specimens as IBWOs, and then upon followup they can't be found. ...Sound familiar?

That, I think, was the gist of the argument. I find it a weak and UNprobabilistic theory, but one I can't entirely rule out... and can't banish from my mind. Surely, by now someone would've captured one of these impostor birds on film, or at some point a follow-up search would be quick enough to spot it and recognize/report the look-alike, even without a photo. Surely? or maybe not? Could such birds account for the few-and-far-between, but never-quite-ending chain of reports over the last 60 years? If "mistakes" are what we are dealing with, I can't come up with any better explanation... (though of course there are still the 'sound' encounters to deal with ...another form of 'mistakes'?)

Through this last Pearl River episode I remarked to some folks that we needed a shot/frame where we could make out the bird's bill --- THAT would move the identification along significantly; to see the IBWO's big, white, honkin' beak stickin' out there. Plumage interpretation in rough video may always be subject to artifactual, illusory, inconclusive elements, but that beak...

That's the best I can do for the skeptical side... and once again, it's not very satisfactory. Someone, puuhh-leeeeze bring me a clear photo of an Ivory-bill (showing the bill)... or, bring me a photo of a Pileated that truly mimics one.
-----------------------------------------------------------------------
Comments:
Just to be very clear on a very important point - To my knowledge there is not a single photograph, nor a specimen, of a pileated that can be described as "partially leucistic," and your statement that such birds "have appeared from time-to-time" is not supported by any evidence I am aware of. Cornell has made clear that not a single anomalous pileated has been reported from the Big Woods, other than the "white" bird. What has been reported, photographed, and even illustrated in field guides are light-colored tips on the flight feathers, particularly the primaries. Such coloring can be quite asymmetric. Whether Snyder's pileated, which was reported to have noticeable asymmetry in the light color on the trailing edges of its wings, was a rather extreme example of such a bird we will never know.

Your question about white on a pileated appearing as a "back mantle" is unfortunately largely irrelevant to the problem at hand. The overwhelming majority of recent sightings have been of birds in flight, not perched birds. The plumage that needs to be explained is on the wings, not the body (although certainly there are sightings in which ivory-bill body plumage, body form, and even bill characteristics are described).

In molting pileateds, white underwing feathers can of course sometimes be seen when they are normally hidden. Many images exist of such birds, and of course there is nothing anomalous about molting. However, molting in and of itself can NEVER produce a white trailing edge on a pileated wing. In one rather bizarre case though, a pileated was reported by Cornell volunteers to be missing virtually all of its secondaries. This gave an impression, at least briefly, of a white trailing edge. But as usual, the bird was quickly identified as a pileated.

Your casual association of two words: "rare" and "occasional" is, if you'll forgive me, a bit sloppy and the distinction is critically important. It seems reasonable to conclude that predominantly black pileateds with anomalous distributions of white plumage (which really should be called piebald birds) must be astonishingly rare. Any such bird seen by any of the official search team members would have been pursued doggedly, and the fact that not a single photograph of such a bird has turned up anywhere speaks volumes. But to explain the sighting evidence over the last 5 years, we must have many such birds, not just turning up in multiple states, but within states over vast areas. In many cases, other details such as glossy plumage, long, pointed wings, long beaks, duck-like flight, and so on, somehow manage to get "filled in" by observers.

There is clearly a need in some quarters within so-called "skepticism" to explain the ivory-bill related evidence that has been accumulated over the last 5 years. But if we are going to hypothesize rare, anomalous pileateds that move anomalous distances and are therefore difficult to document, why not ivory-bills? It seems to me that those who insist on declaring the species extinct are heavily invested in a very specific view of ivory-bill behavior and habitat requirements.

Either way, as I have previously observed, there are difficult patterns to account for. Time will tell.
 
Agree completely with fang's arguments. The "anomalous Pileated" is a unicorn, a dragon, a mythical beast with even less evidence supporting its existence that the Loch Ness Monster has. Not one sighting, photograph, or video has turned out to involve a creature like this, which would be easily relocated given the Pielated's typically well-defined home range and limited wandering tendencies. There is no reason to even consider this possibility anymore; this was settled years ago.

Two phenomena that do need to be considered, though, are the backlit Pileated and the misconstrued Red-headed. The black flight feathers of a Pileated can appear pale when the bird is strongly backlit; an inexperienced and/or incautious observer who sees this could leap to a conclusion; a low-resolution video camera could well be fooled (I suspect this may be responsible for one of Mike Collins' November 3rd videos). Likewise, a Red-headed Woodpecker seen poorly and briefly under circumstances that render distance and size difficult to judge or misleading could lead the same sort of observer to the same sort of erroneous conclusion. These are serious possibilities for sightings by non-birders and other people who lack a track record of reliability in field observations, when the bird was seen only in flight, very briefly, and nothing was noted but the "white trailing edge." They are also vastly more likely than the mythical "anomalous Pileated." If you subtract these sorts of reports, we are still left with several clusters sightings by skilled, previously reliable observers which include significant detail; these clusters still don't explain away.
 
CT: I believe you are going further than I was prepared to on the "anomalous Pileated" theory. I don't, in particular, recall postulating that they "lived shorter lives". I don't recall making any statements about this being a genetic possibility, either. I was thinking, in past posts, I believe, of the idea of an anomalous molt, which does not last long because new feathers grow in and restore normal plumage. I certainly can't take credit for that idea either--I believe that was first postulated on The-Blog-that-shall-not-be-named.
As for anomalous Pileateds being "unicorns", there are a few photos:
-Birdforum post
-Cornell's albinistic Pileated, plus, scroll down to see a photo of a bird with a large white patch showing when perched--would not fool anyone with a good look, but a fleeting look through the trees might be dangerous.

Still, I don't think the anomalous Pileateds account for most of the fleeting IBWO sightings for the last sixty years--I think it is just human nature--we can all see that which we desire so much to see, at least for an instant.
Also, remember the "field guide effect": the bird has been in field guides since the 1960's, listed as "possibly extant". I wrote a post here about that some time ago, but can't find it. (That idea, I will take credit for!)
 
I'm quite happy to go with "mistakes"

You only have to see the hash made of the recent Red-headed Woodpecker video to imagine what might happen in the field.

I even sense Cyberthrush is tip-toeing around that opinion.
 
Cotinis --reread Fangsheath's post; I believe he addresses all of those birds. The third one is a perfectly normal Pileated in molt; those white feathers are in the normal Pileated locations and in flight all the white will be where it belongs.

The non-existent anomalous Pileated I refer to is the hypothetical one with white secondaries on a mostly dark bird.
 
Bill, I agree with you in particular, but not in general.
I agree that it is not plausible to have an "anomalous Pileated" that mimics, to good accuracy with a good view, an IBWO wing pattern.

However, I believe it is possible for a Pileated undergoing molt, or a partially albino Pileated (as documented by Cornell), to fool "some of the people some of the time" when there is a brief or poor look. I feel that is enough to generate a lot of reports, given all the interest in the IBWO. (And I have shared the interest most of my life, believe me.) You and others are, of course, entitled to believe that there is some real IBWO fire for all this smoke. I'll note, too, that it is really hard to see the wing pattern on a Pileated when it is booking along in an escape flight--I've seen that real well once or twice, and it gave me a real impression of "too much white".

The fact that no breeding population has been found five years after the "rediscoveries" in Arkansas and Florida, to me, is enough to quash any hope I had that the species persisted. I have been reading about these isolated, poorly-documented sightings of the IBWO for most of my birding life--since about 1968!
 
Thanks for all the clarifications guys, and apologies Cotinis (PCoin) if I misconstrued your argument a bit (I may have blurred together the suggestions that 2-3 people have made to me over time).
 
Well, of course, as far as I am concerned, the bird WAS conclusively documented photographically in 2004 in Arkansas -- that video shows the white trailing edge to the underwing as the bird launches from and is eclipsed behind the tree (even using Sibley et al's interpretation of those frames), shows no real (i.e. not clearly artifactual) black edges to the underwing fore or aft, and shows a bowed-winged rowing flight style that has never been reconciled with a Pileated no matter what Louis Bevier claims about his secret videos that have never been produced for public viewing. So at the worst the extinction date has to be moved forward to 2004 in my view. As for the anomalous Pileateds, my point is that I see no need to invoke them when you have so many normal Pileateds, Red-headeds, and inexperienced searchers out in the woods to generate brief glimpses of things. And, as everyone seems to chose to not remember, the few rigorous statistical analyses of effort that have been done find that even in the Big Woods, and even discounting ALL sightings as invalid, there still hasn't been enough field effort to lower the statistical upper bound for the population below 1 bird, JUST within the primary search area, not even counting the entire Big Woods ecosystem. Counterinuitive? Sure, it may be. But it's not especially unusual for the results of calculations of probability to feel counterintuitive.

There is no mystery here. There has not been enough effort put in, even if you reject all sightings and assume all observers were fully competent, and search methodologies were effective, to conclude in a statistically meaningful way that there are no birds out there. Non-existence is very very very hard to demonstrate if you don't have a small and well-defined search area and a sedentary organism.

But I and many others have said this same thing dozens of times in the last couple of years, so those who chose to reject the argument are clearly not going to be persuaded otherwise by yet one more reiteration.
 
I posted this same tidbit over on the other thread; I think it bears repeating here as well:

The first Marbled Murrelet nest was not located until 1974. When it was finally discovered it was found in a well-known State Park in one of North America's most heavily-birded Counties (Santa Cruz, CA), about 25 miles from downtown San Jose and 45 miles from downtown San Francisco, smack in the middle of one of the largest concentrations of birders anywhere in the Western Hemisphere. And, it wasn't even found by a birder. At that time the species was still locally common, though it had been in decline for decades.

And yet we're supposed to believe that we certainly should have found an almost extinct bird lurking in a vast area of one of North America's least birded environments in just a few years?

We birders need a serious dose of humble pie when it comes to our fantasies of how efficient we are at searching out birds, especially when we don't know exactly when and where to look.
 
What I find particularly amusing is that birders are simultaneously given too much credit and too little - They are supposed to have been able to find ivory-bills, yet the ones who do, even those who were skeptical before they had the encounter, must be "mistaken" (seemingly the good birders are never liars, that is always made clear). If they are such poor observers, I don't know why we need to resort to any pileated hypothesis - They are seeing piebald crows, anhingas, wood ducks, kites....I would hardly call myself an avid birder, but if I couldn't tell a piebald crow from a woodpecker in half a second I think I would give up on bird observation.

I very much appreciate that some have a need to explain the evidence in some way. It indicates a degree of intellectual integrity, unlike the attitude of others which says that only "claimants" need to explain things. As I have said, there are difficulties no matter what you accept. If the birds are out there, we have been stunningly bad at finding active roosts (nests too, but that should be harder). There are still plenty of independent efforts underway.
 
"We birders need a serious dose of humble pie when it comes to our fantasies of how efficient we are at searching out birds" - Bill Pulliam

I've mentioned this story before, but I think it bears repeating. Near my location east of Oakland California there have been 1-2 Pileated Woodpeckers reported on and off since at least 2000. They are seen in a series of regional parks on the edge of Oakland proper which have deep trail networks, an area of maybe 10 square miles. This area is good for birding in general and there is a high density of birders in the East Bay. Pileated is a very special bird around here, definitely something birders will go out of their way to see.

I checked the East Bay birding mailing list and found about 8 sightings and audio encounters in 2000. In subsequent years there were sometimes been as many as 6 reports in a year, some years only 1 or 2. Sometimes only characteristic Pileated diggings are reported. The occasional reports have persisted ever since. Nobody has reported seeing the bird at a roost or nest in spite of a breeding bird atlas being conducted and intense local interest in the species.

I guess the moral of my story is, for all the Pileateds that are seen in Southern swamps, imagine how many are not being seen. How many more aren't seen because birders don't go into the poorly accessed habitat. Then apply that to the Ivory-bill, which would be much less than 1/1000th as abundant, and the lack of sightings, roosts, and nest holes looks all the more understandable.
 
Even though I have concluded that the IBWO's existence was documented in Arkansas in 2004 and along the Pearl River in 2006 and 2008 and thus I am not a skeptic on the IBWO's existence, I have one tiny disagreement with what Fangsheath wrote above. I agree with skeptics that those making positive statements about the existence of the IBWO must present evidence and explain their conclusions. Just the extreme rarity of this bird would demand this in birding and ornithology circles independently of any doubts about the continuing existence of the bird.

There is also a logical problem with demanding that doubters present an alternative explanation for the evidence. This will depend on what kind of evidence is being considered. In the case of images and recordings one would expect either a reasoning concluding that the image or recording couldn't be produced by an IBWO or that it is indeed produced by some other species. But in the case where the evidence is just a sighting, specially a sighting by a single observer, there are just too many alternatives for one to logically expect a unique explanation for wwhat one judges to be a false report.

The hypothesis that the IBWO is probably extinct was made plausible by the extreme rarity of the bird. Moreover it is a hypothesis that can be empirically investigated and disproved. Disproving it adds to our knowledge of the world. The problem with the hypothesis that the IBWO is extant despite the fact of its extreme rarity is that even if the bird were in fact extinct one wouldn't be able, even in principle, to empirically rule out this hypothesis since "absence of evidence is not evidence of absence."

Clearly this is not a cut and dry thing. The problem of when to consider a species probably extinct is a vexing one for those interested in conservation and has to be somewhat arbitrary by its very nature. Fangsheath probably knows this better than I do.

Dalcio
Gainesville, Florida.
 
The burden of evidence falls upon whoever makes an assertion: "The Ivory-bill persists" or "The Ivory-bill is probably extinct". It is part of the scientific process to be skeptical of the evidence without necessarily asserting the opposite hypothesis. Careful Ivory-bill skeptics merely claim that the persistence hypothesis has not been proven, while others make the logical error of assuming that unproven persistence supports the opposite hypothesis of extinction.
 
Post a Comment

Links to this post:

Create a Link



<< Home

This page is powered by Blogger. Isn't yours?

Older Posts ...Home