Excerpts from the Cornell website
here (the bold font is mine):
“Tyler got a clear look at a female ivory-bill through his binoculars, flying through the forest,” Hill says. “And when Tyler got a clear look—Tyler’s the best field ornithologist I’ve ever been out with—I would trust his sightings better than anybody in North America.”
I wouldn't.
The Florida crew found 20 cavities they say might have been made by an ivory-bill. Fitzpatrick thinks the cavity data are some of the most interesting: “I’m most excited about the fact that they have woodpecker cavity holes, several of which appear to be reasonably fresh and are bigger than the excavations typically made by Pileated Woodpeckers. There’s nothing else that would be digging those except a larger woodpecker. The cavities are the right shape and size and they’re placed in the right spots,” Fitzpatrick says.
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From Pat Leonard's article on the CLO website: "The double knocks are also intriguing, but as the Lab’s acoustic experts found, it’s nearly impossible to say conclusively that they were made by an ivory-bill because similar-sounding double knocks can also be attributed to other sources, such as the flapping of duck wings. One can only say whether the sounds are consistent with the ivory-bill’s drumming pattern. The range of variation in ivory-bill sounds is also unknown, since the only recordings come from one pair of birds during the Allen expedition."
CLO keeps dropping this hint about duck flaps producing double knocks resembling Campephilus drums. This isn't published, and those people who have demonstrated it might want to publish it for themselves. Is CLO trying to claim copyright of that information? Or are they delaying it getting into print for some reason, like it might further call into question double knocks in Arkansas? Wouldn't Hillcrow need to know about this before Mexico?
As far as the range of variation in Ivory-bill sounds goes, a range can be obtained from the approximately 10 minutes of recordings that survives (hundreds of 'kents' to sample). James Tanner listened to all of that and commented in his book about what was and wasn't preserved with respect to the repertoire of the Ivory-bill. Although his words can't be measured to give a range and standard deviation, he did summarize the various sounds very well. The Florida notes superficially match only the 'kent' and then only vaguely. The variation in the Florida recordings includes, as pointed out on this blog before, an average duration twice that known for Ivory-bills and at fairly different harmonic frequencies (this likely explains why most of the FL "putative kents" don't sound like real 'kents'). Tanner did not describe any variant call that encompasses the Florida sounds.
I suppose this has been mentioned before, but if people have been searching for a year, including two men camped out on the Choctawhatchee for 4 months, why would no observer and no ARU ever detect one of the most distinctive vocalizations ascribed to the Ivory-bill by Tanner? Yes, a variation he described and we know about but was never recorded (remember he listened to all that survives and told us so). This vocalization is described as a loud, "prolonged, upward slurring, repeated 'kient-kient-kient'." This was the vocalization that Tanner said could be heard from the greatest distance, so one would presume that an observer or ARU should detect it--even preferentially detect it. Tanner said it was often given from the tops of trees, and could be heard for over a quarter of a mile. Several times he saw two or three Ivory-bills climb together to the very top of a dead-topped tree, chorus together a loud 'kient-kient-kient', and then fly off together. Not surprisingly, this vocalization remains unreported from Arkansas.
Could it be that the better known 'kent' call, which was the only vocalization recorded, is the only search image in observers' minds and therefore the only call sought both on recordings or in the field? There is more known about variation of ivory-bill sounds, Fitzcrow, than is dreamt of in your Laboratory.
This is another twist to this whole saga. Sounds good, people seems to be good natured and believable. I am naturally skeptical...but I do think these "sightings" have more potential than all the CLO "observations". I give them until spring, one winter season to come up with irrefutable proof. Anything short of this...well...you know what that means....nada!
"Could it be that the better known 'kent' call, which was the only vocalization recorded, is the only search image in observers' minds and therefore the only call sought both on recordings or in the field?"
I'm not sure I'm understanding the question, but I think the answer is "Yes".
Wasn't the ARU data extracted by analysts using visual methods and not by computer algorithms? The analysts wouldn't have a way to find something they weren't looking for. They were looking for single musical kents and they found a bunch, but apparently only during daylight hours. CLO and Zeiss weren't so lucky.
"Wasn't the ARU data extracted by analysts using visual methods and not by computer algorithms?
The paper describes the process, and although not explicit, it sounds like the Syrinx software allowed them to see a spectrogram more or less real-time while listening to the sounds. The paper suggests that the authors read the descriptions of known Ivory-bill sounds and based their search analysis on them. As far as searching just for 'kent' sounds goes, that's fine, but it suggests a bias, a sort of fallacy of presumption and bias of "hearing what they expect to hear." It seems misleading to suggest that the difference in context (at a nest) is sufficient to explain why the FL 'kents' are not a good match. This presumes the FL sounds are some previously undescribed Ivory-bill vocalization, when no variant was described that matches these. Guess it will remain inconclusive until someone records similar sounds while watching an Ivory-bill. Good luck, Auburn and Windsor!
One more thing about the duck flaps: the article says that the "Lab's acoustic experts" found this. Is that true or was it someone outside the Lab, maybe just a searcher who established it independently?
Typical overreliance on technology and statistics, a hallmark of modern Science.
Honest scientists would admit that woodpeckers are highly conspicuous, vocal, diurnal birds, easily seen and photographed if present, and would stop trying to fool the public.
This part of Florida probably does hold the best chance for a rediscovery of this species, and I can't criticize these guys for the work which they have done; however, I think that part of the evidence presented so far is somewhat weak, especially the cavities. I thought that Ivory-billeds built cavities under an extended knot or piece of limb. Also, some of the "kent" calls sound more like a Common Moorhen than an Ivory-billed, and a couple of the small holes in the scaled areas of the trees look like holes from a bullet rather than a bill.
On what grounds is rediscovery at all likely in Florida?
If I were foolish enough to look for the SPECIES at this late date my search would be in Cuba.
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