There have been recent rumors, on the Internet at the Arkansas and Tennessee birding listservs and at least one blog, regarding a paper by several researchers, including a well-known Ivory-billed Woodpecker (IBWO) expert, that will question the validity of the Arkansas sightings of the IBWO last winter. [UPDATE: New York Times, confirms in a story on 21 July] This has already caused some uproar and knee-jerk reactions. Here is what I know; before passing judgment on what has come out so far, please read to the end of the post for commentary.
I have it from several sources that the paper’s authors are Richard Prum, Professor of Ornithology, Ecology and Evolutionary Biology, at Yale University; Jerome Jackson, Florida Gulf Coast University and author of the Birds of North America account and a book on IBWO; and Mark Robbins, Collections Manager, Ornithology Division, University of Kansas Natural History Museum. Jackson’s name should come as no surprise, having already been bandied about as an author, and as the only IBWO expert not on the Arkansas Cornell team who is a candidate to write such a paper.
The paper has been submitted to an online journal, which I understand is peer-reviewed and perhaps British, and is the final revision stage. [update and my comment here] The authors of the paper in Science on the Arkansas rediscovery (Fitzpatrick et al.) have been invited to publish a response in the same issue, and they will be doing so.
Prum et al. contend that the images in the David Luneau video, which are the centerpiece of the Fitzpatrick et al. paper, are not an IBWO, but perhaps an abnormally-plumaged Pileated Woodpecker (PIWO). They apparently extrapolate from there that there is not sufficient evidence to conclusively prove that any of the Arkansas sightings are actually IBWOs. NOTE: It is my understanding that Prum et al. do not say IBWOs do not exist, only that the evidence provided for the Arkansas sightings as published is not proof.
Regarding that evidence, I was told by an extremely reliable source that Prum et al. did not request from Cornell permission to look at original data and materials. When Cornell learned that the evidence would be disputed, they offered, for example, high-resolution copies of the video, but were not given sufficient time to deliver these materials The Prum et al. paper is based on the data provided in the Fitzpatrick et al. Science paper and the supplementary materials to that paper available online.
The video clip provided in the supplementary materials online is at 4x magnification at 1/2 speed. Also provided in the supplementary materials are a series of video stills in PDF, which are tiny on a computer screen. Figure S4 provides a graphical summary of a comparison of a critical measurement, as estimated from IBWO and PIWO museum skins, from 1935 IBWO film footage by Arthur Allen, and from the bird in the Luneau video. All estimates of this measurement of the Arkansas bird exceed that of any PIWO they measured (n=24).
I am keenly interested in reading the Prum et al. paper because I am curious how they reached their conclusions given the limited material they worked with. In addition to the video version online, I have seen a much longer high-resolution clip at original speed and magnification, 1/8 speed and 4x magnification, and a series of stills, plus films at similar speeds and magnifications shot by Cornell using IBWO and PIWO models as comparative simulations, which help support the IBWO identification.
Plumage can be deceiving, of course, but size is more convincing. Figure S4, albeit using small sample sizes, is quite compelling in support of IBWO, especially when one examines how Fitzpatrick et al. derived these measurements (I’ve seen these methods and figures, which are not available in the supplement). I am especially curious to see how this is countered.
Here is what we need to bear in mind. The IBWO sightings represent the biggest news in the birding world in recent memory, and the news was accompanied by a fervent and impassioned positive response by the public. If not for that, the fact that there will be a rebuttal to the published report would be a non-event. Criticism of published papers, often based solely on the materials presented, appear all the time in journals. All facts in science are provisional and subject to challenge; skepticism is an accepted and necessary part of the scientific process.
I am a little surprised that although Prum et al. are engaging in a routine and time-honored act — and even without disputing the actual existence of IBWOs — that they would do so at the risk of being viewed by the public as turds in the punchbowl. Perhaps worse for their careers might be their choice of not making the challenge in Science, where the original paper was published, as would be the usual procedure. Science is one of the most respected peer-reviewed publications (which is not to say it is infallible). That Fitzpatrick et al. were able to publish in Science, and were willing to risk their own reputations when other researchers claiming to have authentic IBWO proof has resulted in them being labeled Bigfoot-chasers, adds weight to their findings. We will have to see where the Prum et al. paper is published, but if it is indeed a foreign online-only journal, the choice will no doubt be seen as desperate and the material not held in high regard, deservedly or not.
I am also a little concerned that in today’s political climate, where there is a prevailing anti-science, anti-environmental sentiment, that the criticism will be used as an excuse by some not to spend further money on habitat acquisition, which has been an enormously beneficial outcome of the IBWO reports. I can see those people who would like to see endangered species protections weakened (and who do not understand the scientific process) trumpeting this criticism as an example of how experts cannot even agree on species identification, and therefore requiring hugely inflated standards of proof before management can occur.
This is extremely unfortunate. There is a principle known as Occam’s Razor which states that the simplest explanation is the best. From the complete suite of evidence I have seen, including further audio recordings of both calls and drumming, and details on the methodologies used to reach the IBWO identification, I conclude that the most parsimonious explanation for the findings is that there are IBWOs in the Big Woods of Arkansas, or certainly enough evidence that further exploration and habitat preservation is warranted.
We need to keep the Prum et al. paper in perspective. We need to recognize that Prum, Jackson, and Robbins have all made worthy contributions to ornithology; Jackson in particular has made very important contributions to our knowledge and understanding of IBWOs. And most of all we need to respect that the model for the scientific method relies not on taking matters at face value, but examining facts critically by offering challenges and counter-challenges. Rather than presume the Prum et al. paper was motivated by personality conflicts and egos, as some have suggested, I hope that it is in the spirit of scientific inquiry that Prum et al. present their publication.