Wednesday, January 03, 2007

Can't sit still quietly for this one...

Comments on this post on Tom Nelson's blog, which intend to summarize the reasons why the Luneau bird has been conclusively demonstrated to be a Pileated, in fact sumarize why these reasonings are all fundamentally flawed:

Arkansas duck hunters still skeptical

Some key claims (and their refutations) include:

1. The Luneau bird unequivocally displays a black trailing edge to the underwing; its seeming narrowness is a result of white bleed.

The Luneau images show black on the leading edge of the bird's underwing as often as they show it on the trailing edge. Neither IBWO nor PIWO should show a black leading edge to the underwing. The "black trailing edge" is never more than one pixel wide, and is inconsistent. Ergo, the Luneau video does NOT clearly show a black trailing edge to the underwing. It is perfectly consistent with an underwing that has white at the leading and trailing edges. Artifactual black edges to bright areas are abundant in the video frames. On the second point, white bleed is not occuring prominently in the video. This is shown clearly by looking at the outlines of tree trunks where they pass in front of bright and dark areas in the background. Where they pass in front of white, they generally do NOT show white bleeding (which would indent their apparent edges); instead, they often show spurious black edges at the light-dark interface. Blurring of the underwing is a result of motion blur, not white bleed.

2. If frame 33 and 50 show an extended wing, the bird is a PIWO.

I agree that frame 33 and 50 probably show the hind portions of the underside of an extended wing. But this hind portion appear to be predominantly or exclusively white, even in frame 50 as it is eclipsed behind the tree trunk. Sibley's drawing that tries to make this a black-edged pileated wing shows an absurdly and unrealistically narrow black edge. And, even if you are going to blame this narrowness on white bleed, you won't get white bleed from the part of the wing that is behind the tree trunk and not visible!!! In frame 50 only a narrow fringe of the trailing part of the underwing is visible, yet the dominant color in this narrow fringe is still WHITE. So even this interpretation of these frames does NOT indisputably support a PIWO ID; indeed it seems to lean towards an IBWO ID.

3. Sibley, Kaufmann, and Bevier all have concluded the bird is indisputably a PIWO, and who are we to question them?

Sibley: His analysis of the video, as I mentioned above, shows a ridiculously narrow black trailing edge on the bird's underwing. White bleed may be invoked as a justification for this, except that white bleed is not much in evidence elsewhere in the video. Motion blur affects black and white equally. He also embraces the intermittent, teeny, and narrow black trailing edge, while dismissing the similar black leading edge as an artifact. And, he stops his sketches at the point where it starts to get difficult, where the bird begins to level and then rise relative to the line of sight, and the hypothesis that all the white is on the ventral wing surface becomes much harder to support. Most glaringly, he completely ignores the blatant fact that the wing postures he draws (with which I have no argument, my own sketches show similar postures) are entirely unlike the wing motions show in PIWO comparison videos. The PIWO videos I have seen show a quite consistent (flat!) wing geometry during the downstroke; the Luneau bird shows something very different.

Kaufmann: So far as I know, he has never given his reasons for stating the Luneau bird is a PIWO. An opinion not backed up with reasons is not something that needs be discussed in a scientific debate.

Bevier: He rules out IBWO based on what he sees as a PIWO-shaped black wingtip on the underwing. This is an interesting case, where the Luneau video is first described as very poor and showing no detail, then it is claimed that it shows a detail that rules out IBWO. The shape of the black area on the distal end of the rapidly moving underwing cannot be determined with any detail, given the motion blur and abundant spurious black edge artifacts. It can only be determined that some black area of about one pixel in extent occurs there. This is true for bith PIWO and IBWO. Bevier's smoking gun in fact is shooting blanks.

Who are we to question these authorities? Interesting statement from people who claim that mutiple ornithologists at Cornell and Auburn, the Arkansas bird records committee, and Science Magazine have all committed astounding errors. These gentlemen (S, K, and B) may be experts at bird ID, but are they experts at forensic analysis of crappy video? Experts are mistaken all the time, experts are just as much subject to group mentality, axe grinding, reputation salvaging (Sibley and Kaufmann published the first two "comprehensive" North American bird guides that left out the IBWO; they were among the few American bird experts who stepped forward and prominently declared the IBWO extinct, not just possibly or probably extinct), emotional responses (Sibley describes weeping with feelings of betrayal on first seeing the Luneau video and how crappy it was), etc.

Enough for now. Before you start telling me what an idiot I am, please be familiar with the full exposition of my own Luneau interptetations:

Luneau postings index

And since apparently some of the people who read my blog are not good with details, I'll make this as obvious as I can:


The Luneau bird may not be indisputably an Ivorybill, but neither is it indisputably a Pileated. In fact, it shows several characters that are notably inconsistent with a PIWO ID. This is my conclusion. Yours may differ. Neither of us is infallible or omniscient.


At 6:45 PM, Anonymous David L. Martin said...

Bill, you and I have been trained to distinguish between good science and unfalsifiable pseudoscience. When we see blatant double-standards, wildly inconsistent application of methods and principles, distortion of evidence, and very selective appeals to authority, we know what we are looking at. I do not waste my time with it, I see it as an impossible tar baby. But I appreciate your thoughtful treatment and of course all your hard work on the video. I continue to consider the wingbeat rate one of the most critical lines of evidence.

At 12:02 PM, Anonymous Sidewinder said...

One day we will all smile as we reflect on the great controversy the Luneau video has stimulated. With so much energy now being invested in the swamps, either the elusive photo/video will be obtained or the interest, hope, and motivation of searchers will eventually subside. With so many PIWO videos being acquired (the wild card: what does Cornell now have?), we'll learn much more about their flight dynamics and whether or not they are consistent with the Luneau video. Hindsight will be very telling. In the meantime, I'm amazed by the number of those who go out on an all-or-nothing limb (Luneau = 100% IBWO or 100% PIWO). I do like your caution, Bill.

At 1:45 PM, Blogger Bill Pulliam said...

I honestly have my doubts as to whether everyone will be smiling if a hi-def video of impeccable origin is produced; ego often trumps all. And if no more is ever found and extinction becomes generally accepted, that isn't something anyone should smile about; but a few people doubtless will.

I try to distinguish between personal beliefs and scientifically supportable beliefs. It is nice when they coincide, but most real humans have to settle for broad overlap rather than complete agreement. I find that Luneau contains some features that appear inconsistent with the (very well known) PIWO, and no features that are clearly inconsistent with the (very poorly known) IBWO. Others have found differently, and I have pointed out where I and why I think they are mistaken. Others will. So it goes in the world of science.


Post a Comment

<< Home

Site Meter