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. 2023 May 18;13(5):e10017. doi: 10.1002/ece3.10017

FIGURE 1.

FIGURE 1

Audiospectrograms of recorded sounds: (a–h) calls extracted from ML6784 recorded by A. Allen and P. Kellogg in the Singer Tract in April 1935 and known to be Ivory‐billed Woodpeckers (the Singer recordings); (i–m) calls extracted from ML104395 recorded by J. Dennis in the Big Thicket, TX, in February 1968 and assumed to be an Ivorybill, although the birds were not seen while recorded (the Dennis recordings); (n–q) calls recorded by M. Courtman with P. Vanbergen in the Louisiana study area in March 2017 using a Zoom H4N handheld recorder. Selections from ML6784 were chosen for the range of kent calls given. Selections from ML 104395 were made on the basis of minimal sound signature overlap. Most calls audible on the Courtman recording had at most a tracing with a single frequency at about 1750 Hz. Those selected for the comparison were among the rare tracings with multiple visible harmonics. Audio recordings of the M. Courtman examples are available in Appendix 2.