@article{cc9ee5808e8740dc983d0001fc39e14a,
title = "Subspecies discrimination based on song structure by Willow Flycatchers",
abstract = "Animals use acoustic signals to repel competitors and attract mates, and signal divergence among populations can promote reproductive isolation. Empidonax flycatchers are insectivorous songbirds distributed across North and Central America that are conservative in plumage, but often exhibit differences in songs both among and within species. Four subspecies of Willow Flycatchers (Empidonax traillii) have been recognized and previous analyses have revealed differences in song structure among a subset of these subspecies. Using reciprocal playback experiments in the field, we tested for subspecific song discrimination among these four putative subspecies of Willow Flycatchers. We found that three subspecies (E. t. adastus, E. t. brewsteri, and E. t. traillii) responded similarly to their own songs and those of each other, but all three subspecies responded significantly less aggressively to songs of the southwestern subspecies (E. t. extimus). In contrast, the southwestern subspecies (E. t. extimus) responded significantly more aggressively to its own song than to those of the other three subspecies. Our results indicate that behavioral responses reflect differences in song structure among subspecies; subspecies responded more strongly to songs of subspecies with similar structures, less strongly to songs most different in structure, and the subspecies with the most distinctive song (E. t. extimus) responded less to songs of the other three subspecies. If responses of males to songs reflect relative reproductive compatibility within and among subspecies, songs may contribute to reproductive isolation of the four subspecies of Willow Flycatchers.",
keywords = "Empidonax traillii, behavioral isolation, playback experiment, reproductive isolation, suboscine",
author = "Mahoney, {Sean M.} and Bret Pasch and Theimer, {Tad C.}",
note = "Funding Information: This work was supported by the T & E Inc. Conservation grant (SMM), the NAU John Prather Conservation award (SMM), and the NAU Landscape Conservation Initiative Fellowship (SMM). Field assistance from S. I. Gonzalez was invaluable. Tom and Allison Mickel (Eugene, OR) provided crucial field site consultation for playback studies. M. J. Whitfield, M. A. McLeod, A. Pellegrini, G. C. Cummins, M. J. Johnson, and D. Moore provided critical field assistance. We thank C. E. Aslan and S. M. Shuster for reviewing early drafts of this manuscript. Reviews by one anonymous reviewer, M. J. Whitfield, E. Paxton, and G. Ritchison substantively improved this manuscript. Research was conducted in compliance with NAU IACUC and the USFWS. Video files, song stimuli used in playback experiments, and raw data are available in the Dryad Repository. Funding Information: This work was supported by the T & E Inc. Conservation grant (SMM), the NAU John Prather Conservation award (SMM), and the NAU Landscape Conservation Initiative Fellowship (SMM). Field assistance from S. I. Gonzalez was invaluable. Tom and Allison Mickel (Eugene, OR) provided crucial field site consultation for playback studies. M. J. Whitfield, M. A. McLeod, A. Pellegrini, G. C. Cummins, M. J. Johnson, and D. Moore provided critical field assistance. We thank C. E. Aslan and S. M. Shuster for reviewing early drafts of this manuscript. Reviews by one anonymous reviewer, M. J. Whitfield, E. Paxton, and G. Ritchison substantively improved this manuscript. Research was conducted in compliance with NAU IACUC and the USFWS. Video files, song stimuli used in playback experiments, and raw data are available in the Dryad Repository. Publisher Copyright: {\textcopyright} 2021 Association of Field Ornithologists",
year = "2021",
month = jun,
doi = "10.1111/jofo.12366",
language = "English (US)",
volume = "92",
pages = "173--183",
journal = "Journal of Field Ornithology",
issn = "0273-8570",
publisher = "Wiley-Blackwell",
number = "2",
}