Hill et al. - acoustic evidence
putative kents - Assuming that recordings were made day and night, as implied by the authors, putative kents occurred only during daylight and in fact never before sunrise or after sunset. There were two peaks, one in mid-morning (9:00-10:00) and another in late afternoon (4:00-5:00). This would seem to eliminate wind as a source. When putative kents for a given day are strung together it is clear that many of them are coming from the same source. However, it seems equally apparent that some are very different from others. Particularly, most of the putative kents recorded after 3/13 are relatively high pitched and have few harmonics. Virtually all of these notes have 3 frequency peaks separated by about 900 Hz, the first peak at about 850 Hz. This is a very poor match to known ivory-bill kent calls, which have frequency peaks separated by about 650-700 Hz beginning at about 630 Hz. It is also notable that many of these calls have no double-knocks associated with them. In fact, double-knocks drop off after mid-Mar and several days, including 3/15, 3/16, 3/22, 4/4, 4/9, and 4/11 have multiple putative kents with no double-knocks at all. Many of these putative kents follow the pattern I have indicated above. Many putative kents recorded earlier in the season, when double-knocks are common, are quite different. They are often lower-pitched, sharper, more nasal, and much less mechanical-sounding to my ear. They tend to exhibit many frequency peaks, the louder notes having a base frequency at about 550 Hz and the harmonics spaced about 550 Hz. This is exemplified by a fairly loud putative kent recorded at 11:34 A.M. on 2/10. This note has at least 9 frequency peaks, spaced about 550 Hz apart. Although this not an extremely good match to known ivory-bill notes, it is pretty close, and these may not be kent calls but some other ivory-bill vocalization. If they are bird sounds it is difficult for me to envision what species they might be other than ivory-bill. Lame suggestions such as blue jay, nuthatch, or heron are hardly worth considering. We are talking about multiple notes over periods of days, with no accompanying calls remotely like any of those species. Anyone who has spent a lot of time in southern swamps knows that these are very unusual sounds. However, we don't know for a fact that they are bird sounds, and it does seem odd that with all of these putative ivory-bill notes there is not one example of a series of relatively quick kent-like notes, as was recorded on 4 days in Ark and at the Singer Tract. One series of putative kents, that recorded on 1/22, seems rather moorhen-ish to me. These notes have about a 950 Hz spacing between peaks, quite un-ivory-billish, and moorhen sometimes do give occasional single notes like this.
putative double-knocks - Double-knocks were only recorded during the day. There was a peak in early morning (6:00-9:00) and another sharp peak in late afternoon (3:00-5:00). A few double-knocks were recorded before dawn but only a few minutes before. None occurred after sunset. These patterns are a sharp contrast the Arkansas results, in which double-knocks peaked pre-sunrise and just post-sunset. Florida double-knocks varied in internal knock spacing, with a mean of 115 msec. Arkansas double-knocks presented on the CLO website appear to have a knock spacing of 70-105 msec. Florida double-knocks within bouts tend to have similar internal knock spacing - compare the spacing of the series of 4 recorded on 1/20 to that of the series of 2 recorded later that same afternoon.
The incongruities between the Florida, Arkansas, and Singer Tract acoustic results are troubling. After the "killer" video is obtained (or perhaps even before) I hope that the Florida researchers will employ direction-finding to pinpoint the sources of sounds. This would not only potentially help to get estimates of the number of birds in the area but help reveal movement patterns and provide stakeout points. It would also eliminate confusion with distant sounds and pinpoint mechanical sources of kent-like sounds.
These remarks were intended for grownups. I welcome constructive criticism. Destructive or infantile remarks will be assiduously ignored.
Part of the lunacy of these threads, I suppose. 
