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The apparent rediscovery of the Ivory-billed Woodpecker Campephilus principalis in Arkansas, USA, …


Biology Articles » Zoology » Ornithology » Video analysis of the escape flight of Pileated Woodpecker Dryocopus pileatus: does the Ivory-billed Woodpecker Campephilus principalis persist in continental North America? » Figures

Figures
- Video analysis of the escape flight of Pileated Woodpecker Dryocopus pileatus: does the Ivory-billed Woodpecker Campephilus principalis persist in continental North America?

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Figure 1. Comparison of selected frames from the video presented in Fitzpatrick et al [1] of a putative Ivory-billed Woodpecker from the 'Luneau video' (Top row, A), and selected frames from David Nolin's video of known Pileated Woodpecker (Bottom row, B). Numbers in A identify the frames presented in [1]. In B, represent the decompiled frame numbers from DN's video. Frames chosen in A are representative of each phase of the Luneau bird's flight action, on the upstroke rising directly away from the observer (600), at the top of the upstroke flying obliquely away from the observer (366.7), at the midpoint of the downstroke flying directly away from the observer (283.2), towards (416.7) and at (300) the bottom of the downstroke. Each phase of the wingbeat cycle is consistent with frames of known Pileated Woodpeckers presented in B. There are striking similarities. The images confirm the hypothesis that the impression of extensive black wingtips recorded for the bird in the Luneau video (highlighted by white arrows in the original published images) was in fact produced by the extensive black trailing edge of a Pileated Woodpecker. It seems possible that the black trailing edge to the wing of Pileated Woodpecker was often visible in many frames of the Luneau video, but it was misinterpreted as black wingtips. The flicker and extra wings in B, frame 758 are artifacts of the impossibility of deinterlacing the video, but each wing image is clearly separable. Reproduced from [1] with permission from David Luneau.

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Figure 2. A copy of Figure 1 with plumage similarities between comparable frames highlighted. (A frame 600 and B 302): green arrowhead, black body with white of opposite wings apparently almost meeting; red arrowheads, apparent white trailing edge to wings. (A frame 366.7 and B 775): note these images are in reverse orientation with respect to each other because the bird in A is flying away to the right, whereas that in B is flying away to the left. Yellow arrowheads, inconspicuous trace of black trailing edge to underwing; Red arrowheads, apparent black wingtips; green arrowhead, apparent white trailing edge to upperwing; blue arrowhead, black upperwing with apparent white leading edge (purple arrowhead). (A frame 283.3 and B 758): blue arrowheads, black wingtips on apparently largely white wings; red arrowheads, apparent black leading edge to upperwings; green arrowheads, narrow, apparently all black body. (A frame 416.7 and B 457): yellow arrowheads, all black body (no white); green arrowheads, apparent black wingtips, in fact black trailing edges; red arrowheads, apparent black leading edges to wings; blue arrowheads, apparent smudges on white surface of wing. (A frame 300 and B 175): red arrowheads, apparent black wingtips. In the upper panel (the putative Ivory-billed Woodpecker), although partly obscured by a tree branch the black appears to wrap around a large panel of white in the wing (see also frame 416.7). This is difficult to reconcile with the plumage of Ivory-billed Woodpecker, except as an artifact of rapid motion, but in the lower panels is clearly identifiable as consistent with the black wingtips and trailing edge surrounding the white panel on the underwing of Pileated Woodpecker. Purple arrowheads, largely white underwing white wing surface with dusky markings, a pattern which can be characteristic of Pileated Woodpecker due to the fact that the inner wing is not translucent because of the backing of bone and other thick tissues. The white arrows were superimposed on the original figures in Fitzpatrick et al [1]. Reproduced from [1] with permission from David Luneau.

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Figure 3. Direct comparison of 36 frames from the Luneau video (selected frames in order from 183.3 ms to 966.7 ms; top line of each row) with equivalent frames from the fourth flight of Pileated Woodpecker in David Nolin's video (all of frames 754–789, bottom line of each row). The fourth escape flight from David Nolin's video was chosen because it most closely matches the trajectory of the bird in the Luneau video. Luneau data was presented at twice the frame rate of the Nolin video (which was a standard 29.97 frames s-1), so not all Luneau frames are shown here. The frames in each case start at the midpoint of the second wingbeat after take-off, and continue to almost the midpoint of the ninth wingbeat. Because after the fourth wingbeat, the Pileated Woodpecker in the Nolin video slows its rate of flapping, the two comparisons are not to the same timescale (Pileated sequence = 1.08 s, Luneau sequence = 0.78 s). White squares at the top of the Luneau video sequence indicate an omitted frame. The Pileated Woodpecker flies consistently obliquely away to the left, whereas the Luneau bird initially is flying obliquely away to the right. For every field, in sequence, of the Nolin Pileated video, an equivalent frame, in sequence, of the bird in the Luneau video is available. In most frames, the similarities are striking, and in no case is there a clear plumage feature on the bird in the Luneau video that is incompatible with the known Pileated Woodpecker. In contrast, note frame 350 of the Luneau video, which unambiguously shows the wing patterns of a Pileated Woodpecker. Reproduced from [1] with permission from David Luneau.

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