Rapid Evolution – I Think Not: More on Game Cams and ChallengesPosted: September 13, 2014
Cyberthrush’s blog has been an important resource for people with an interest in the IBWO for nearly a decade. I’ve agreed with him at times and have taken strong issue with him at others. His latest post falls into the latter category and strikes me as being somewhat irresponsible; it’s worthy of submission to The Annals of Armchair Quarterbacking. I responded in the comments but have some additional observations that seem better suited to posting here.
The inspiration for Cyberthrush’s post is an image someone sent him of suspected bark scaling low on a tree. The image is not shown in the post, but I suspect I’ve seen it and, if so, am sure it was the work of a mammal. In any case, he hypothesizes that the IBWO has rapidly evolved to live almost exclusively in the canopy. He uses the specialization of certain species – seabirds, Chimney Swifts, and warblers – to draw parallels, ignoring entirely that none of these species evolved nearly so rapidly. The only basis for this theory is the failure to obtain clear photographs.
He digresses to dismiss virtually all the photographs of feeding sign, cavities, and putative IBWOs and virtually every recording of putative kents or DKs he’s seen over the past 9 years. He writes: “I don’t want to discourage people from sending such things along, but I do want folks to know that the chance of getting a positive response from me is extremely slim . . .”
He goes on:
“I’m in the camp that believes any remaining IBWOs have evolved heightened wariness and caution, and as such DO NOT spend ANY extensive time at ground level, where they would be far more vulnerable. In fact, I believe they are now almost exclusively residents of the upper canopies, other than when flying from point A to point B and requiring a clear pathway. While they might land momentarily lower on a tree, they probably spend most of their daily lives minimally 35+ ft. high up (maybe 50+ ft.) on tree trunks/branches and inside cavities, well above levels frequented by Pileateds and other woodpecker cousins (and generally out of easy sight-line for searchers). It’s not clear to me how many of the remote automatic camera traps were ever set that high (though it’s clear several were not). Like Swifts in the air and Albatrosses at sea, I think Ivory-bills may spend most of their lives solely in the canopies… if you send me a photo of foraging sign or a cavity or a fuzzy bird lower than ~35 ft. high, I probably won’t take it too seriously (even though there are historical records of such cases), unless there are overriding additional details to catch my attention. If Ivory-bills currently lived and foraged below 35 ft. to any significant extent I believe we’d have the definitive evidence we need by now (well before now!); only perhaps as a denizen of the upper reaches might they be able to carry on successfully, while also evading encounters and detection to the degree they have . . .”
I don’t know who else is in his camp. Some have certainly argued that hunting pressure led the IBWO to become hyper-wary, and I can accept that hypothesis to some degree, although I think scarcity and the nature of the habitat have far more to do with the lack of conclusive documentation. The suggestion that the species evolved to exist almost exclusively in the canopy, when it was not infrequently seen feeding near the ground, is nowhere near as plausible, and it’s invented out of whole cloth.
As I wrote in the comments:
Your exclusion of any work below 35′ is arbitrary and wrongheaded, IMO. Forget Allen and Kellogg, Tanner even observed that they’re “not averse” to coming near the ground. Do you really think such a significant behavioral change evolved post-Tanner? An animal seeking food is going to go where the food is, and as it happens, the largest quantity of food is often to be found in the boles. I agree that cavities will be high up and also that work that’s exclusively near the base of the tree is suspect, but when the work goes higher than about 10 feet you can pretty well rule out a mammalian source (unless giraffes are around or there’s some heretofore undiscovered porcupine species in the swamps of Louisiana and Florida). When it’s very extensive, you can be pretty confident that it’s either PIWO or IBWO, and as I’ve argued at length on the Project Coyote blog, I think there is a limited range of work that is identifiable as IBWO.
One avian example of rapid evolution (though not nearly so rapid as Cyberthrush’s IBWO) is the Cahow, but that adaptation involved a change in nesting behavior due to a lack of adequate sites, something that’s far more akin to the kinds of survival strategies discussed in this recent post. There’s simply no reason to think that IBWOs could have suddenly evolved to live almost solely in the canopy. Not when Allen and Kellogg even observed one feeding on the ground; not when Kuhn observed one feeding a foot up; not when one of the clearest photos of bark scaling shows the work going to the base of the tree (the bark chips in this image are worth a close look, and they resemble many that we have found.)
With regard to aiming cameras at the canopy, I discussed the limitations of game cam technology in this post. The challenges increase dramatically when the cameras are aimed even higher, as is illustrated in this photo of a bird about 75’ up in a tree. There’s simply no way to get a conclusive ID. I think it’s suggestive of a female IBWO and that red would be visible in the crest if it were a PIWO, although it’s clearly nowhere near as intriguing as our other two Reconyx photos. Frank disagrees and thinks it could be anything.
Either way, aiming these very poor resolution, short focal length cameras high complicates matters exponentially. The likelihood of getting a clear image at such a great distance and with backlighting is infinitesimal. Aiming high is likely to be a wasted effort. One final note about game cameras, Cyberthrush attaches a great deal more significance to the lack of photos than I do. As far as I’m aware game cameras were only extensively deployed in Arkansas, South Florida, and the Choctawhatchee. They’ll only work if they’re deployed at the right time and in the right place, something that’s much easier said than done. As I’ve mentioned previously, virtually all the scaling we’ve found seems to have been done in a very limited number of visits to the tree, perhaps just one, and in the very rare instances where we’ve found evidence of a return of whatever removed the bark, there has been a gap of several months between visits.
The key to all of this is going to be finding a roost or nest site (unless someone gets extremely lucky.) I’m convinced that feeding sign is what can point searchers in that direction; it’s what led Kuhn and the Allen and Kellogg expedition to birds in the 1930s. That’s the reason for my focus on it. Cyberthrush does a disservice to all searchers by suggesting, based on unfounded speculation, that virtually anything found below 35’ feet is not worthy of attention.