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Mystery Bird Meets Imperial Woodpecker – Trail Cam Photos Revisited (Part 2)

If you haven’t done so already, please read Trail Cam Photos Revisited for a more comprehensive discussion of the image that’s central to this post (including an explanation of our conclusion that the mystery bird is larger than a Pileated Woodpecker). At the time of writing, I didn’t envision doing a follow-up, but the nagging sense that the Rhein Imperial Woodpecker film might be even more relevant than I thought initially led me to go through the film again and pull an additional frame that showed the body profile, with neck extended, more fully and accurately. While I added an update to the original post that included a brightened composite for comparison, there’s a bit more to say.

We’re aware that many (perhaps most) in the scientific and birding communities will accept nothing less than a clear, high quality photograph (or series of photographs) or video. We’re also aware that many people will dismiss any post-processing whatsoever, even when intermediate steps are shown and the processing is relatively limited (in this case only involving the removal of motion blur). I must add, as should be evident from the images in this post, my skills with photographic post-processing tools are very limited. (Patricia Johnson, my wife, had to talk me through the rotation of the images in Photoshop.) Nevertheless, we think comparing the de-blurred mystery bird with frames from the Rhein film showing an Imperial Woodpecker in flight with similarly positioned wings makes a compelling case that our mystery bird is indeed an Ivory-billed Woodpecker.

Our choice of location for the game cam deployment was not random. As with this image (from our old search area), which was obtained a week after a sighting in the same location, the camera was deployed in an area where we’d had recent possible contacts – multiple double knocks (scroll to the end of the trip report) heard within a few hundred yards before and during the deployment, about a week before the image was captured. We also recorded an apparent double knock on the day we retrieved the cards. Thus, in both instances there was a close temporal association between a putative encounter and obtaining (at worst) a strongly suggestive trail cam capture. But I digress . . .

To return to the Imperial Woodpecker, these two screen captures are the most salient.

Screen cap of Imperial Woodpecker in flight, shortly after take-off, at a different angle, but with similar wing position.

Screen capture of Imperial Woodpecker in flight, shortly after take-off, at a different angle, but with similar wing position.

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Screen capture of Imperial Woodpecker in flight.

I was unable to find frames in the film that replicate the angle from which the mystery bird was shot. In the first of these two frames, the bird is flying downward and is angled slightly away from the camera, obscuring the bill and foreshortening the neck and tail. The second is a ventral view from behind, and the bird is angled downward. Our mystery bird is ascending and is seen in profile. Nonetheless, the similarities in both the extent of white on the wing and physical structure are striking. This becomes even more apparent when the Imperial frames are rotated and sized to match the mystery bird. Be sure to click on the images to see the full sized versions.

Rotated, resized image of Imperial Woodpecker in flight. The bird is angled downward and slightly away from the camera obscuring the bill and foreshortening the profile.

Rotated, resized image of Imperial Woodpecker in flight. In the original, the bird is angled downward and slightly away from the camera obscuring the bill and foreshortening the profile.

Imperial Woodpecker in flight. Rotated and re-sized for comparison with mystery bird.

Imperial Woodpecker in flight. Rotated and re-sized for comparison with mystery bird. Although this is a more ventral and posterior view, the similarities in structure are dramatic.

I concluded the previous post by observing, “We realize that this is far from conclusive but can think of few alternative interpretations, all of which are problematic.” Based on the comparison with known stills of the Imperial Woodpecker, I am now firmly convinced that the mystery bird is an Ivory-billed Woodpecker and do not think there’s a reasonable alternative explanation. Frank’s comment was, “People have been executed on far flimsier evidence.”

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George and Nancy Lamb’s 1957 Cuban Ivorybill Study

I have been re-reading George Lamb’s 1957 report on the Cuban Ivory-billed Woodpecker. A number of items struck me as potentially significant for North American searchers, some for how they diverge from Tanner and others for their level of detail. Since this report is likely unfamiliar to many, I thought I’d do a quick post listing some of the more interesting observations

Lamb references a number of local sightings of “groups” of ivorybills, with one report to John Dennis that involved six birds. Notwithstanding, Lamb estimated the population density in Cuba to be much thinner than in the Singer Tract, at one pair per 12-25 square miles. He also pointed out that “ . . . the Cuban Ivory-bills are living for the most part in a cut-over pine forest where only small and deformed trees remain.”

The Cuban ivorybills fed on pines and hardwoods more or less equally, although most of the feeding sign was found on pines, due to the difficulty of searching for sign in the denser hardwood habitat. Roosts and nests were found exclusively in pines (one unused cavity was found in a hardwood), which is interesting in light of the fact that hardwoods were also available. Cavities were found at heights ranging from under 20 feet to nearly 60 feet. Cavities were higher in mature forest; Lamb suggested but did not conclude that the preference was for higher cavities and that the lower ones reflected an adaptation to cut-over conditions.

Lamb describes a female scaling bark: “At this point she was only about 25 feet away while she was feeding around the base of a small pine. She began ‘barking’ this tree about 30 inches from the ground and slowly worked up to the top.” Dennis too had observed birds scaling small pines. They found more scaling than excavation.

This apparent preference for pines, including small ones, may be significant, particularly since the hardwood areas were “relatively untouched”.

An estimated 17 birds were killed by humans over a ten year period, a huge number for such a small population. And it seems an open question whether the thinner population density noted by the Lambs was due to habitat quality, hunting pressure, or a combination of the two.

Regarding flight style: “. . .the flight of the Cuban Ivory-billed Woodpecker was always level and purposeful. They are strong fliers, capable of covering considerable distance in little time, as indeed they must to live successfully in cut-over woodlands. Although the Ivory-bill did not seem to undulate in its flight, the wing beats were not steady, having an almost imperceptible 2-3-2-3 rhythm.”

There’s no mention of double knocks, but calls are discussed. Lamb describes the sound as like the “note of a penny tin trumpet . . . short and usually repeated in a series of single-double-single beats, or it may begin with a double call: that is a high nasal “pent, pent-pent, pent”, or just “pent-pent”. On several occasions the female Ivory-bill most frequently observed made a few long and very loud calls, soon after leaving here roost tree in the early morning. The notes were of greater duration than normal and were repeated in a series of sixteen to twenty-two kients.”

Food for thought . . .


Rapid Evolution – I Think Not: More on Game Cams and Challenges

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.

This really is giraffe foraging sign, photographed in Louisiana . . . Long story.

This really is giraffe foraging sign, photographed in Louisiana . . . Long story.

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.

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Reconyx image and detail. Old Project Coyote search area, March 2009

Reconyx image and detail. Old Project Coyote search area, March 2010

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.

Heavily scaled young oak with suspected IBWO work extending from the base to well up on the trunk.

Heavily scaled young sweet gum or oak with suspected IBWO work extending from the base to well up on the trunk. Note the large bark chips at the base.