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Mob tape + marsh and house wrens calling; PAWR is the incessant "tchiump" call
Detalhes da observação
See encounter notes by David Muth Notes from spec (Marky): The most crucial part of identifying Pacific from Winter Wren at this time of year depends on the “jit”(pacific) or “vimp”(winter) call. Upon obtaining a poor recording of this call from the stub-tailed wren observed, I was later able to compare it to samples of both Winter and Pacific Wren calls uploaded on Xeno Canto. The selection process of these recordings was mostly based upon quality and “regularity” (choosing cuts that sounded most typical of each species). I did attempt to select a cut or two where the call given by each respective species was a bit different from typical, as variance exists, although this was hardly scientific. I then proceeded to randomly select a call or a set of calls in each recording to screenshot and measure using Raven Pro software. I then crudely pasted the screenshots of each recording together in photoshop and attempted to line up the Y axises as best as possible (This task likely could be achieved in a much neater style using some R package but no one has time for that). In terms of analyzing the spectrograms, the first thing I looked at was simply shape. In the winter wren cuts, the calls are characterized by a wide “hump,” where each hump has relatively equal sides (both an up and a down part, although the left side, or the “up” side can regularly be a bit shorter. In Pacific Wren cuts, this shape is more akin to a “ramp.” The right, or down, side is longer and more steep, with the top of the hump a sharp and narrow angle (in some instances Winter Wren can have a sharp angle, but it is wider). Next I looked at frequency-specific marks (Y axis numbers in kHz). Every winter wren cut, good or poor recording show a small mark at or below 2kHz in each call. Pacific Wrens do not show a distinct single mark around 2kHz, but rather the lowest part of the call starts at ~3kHz and is a mirror of the sharp angled section as it descends to below 2kHz. Next I looked at the darkest section of each spectrogram, indicating the loudest part of the call. In Winter Wrens, this darkest or loudest section is the dominant hump shaped call around 3kHz. Some instances the 2kHz mark can be just as dark, but generally 2-3kHz is where the Winter Wren call is the darkest. In Pacific Wren, there are two distinct sections in their call. Both sections are similar in shape (the sharp ramp shape) and are similarly dark. Each ramp shaped section occurs at both 2-4kHz and at 5-7kHz. This distinctly doubled call appears diagnostic. In terms of variation in this two-parted, ramp shaped call, some Pacific Wren calls show multiple bands within these double bands. In XC422034 (furthers left) and XC35439(third from left), multiple smaller bands can be seen within the calls. This is actually present in all the given Pacific Wren calls, but is harder to see in the others. This is another mark not seen in any Winter Wren calls looked at. Finally, I will also point out that the harmonics in winter wrens (harmonics are the lighter bands above the darkest section- they look like layers) almost never follow or mirror the shape of the loudest section. These harmonics are generally much shorter and appear as only half of the hump (generally the “up” part). With all that being said, the Louisiana bird that was recorded gave several calls. All of these calls, although faint, strongly resemble the double-sectioned, ramp-shaped call of Pacific. It even shows smaller bands within the call like Pacific. There is also no 2kHz mark and there are no additional shorter harmonics present. I also measured length, and it appears that WIWR calls can be longer than Pacific, but seem rather variable and possibly not diagnostic. These notes will likely be continually edited for clarity.
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