Song dialects of the Mountain Chickadee (Poecile gambeli) in the sky islands of New Mexico

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2024-05

Authors

Anderson, Mary Beth

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Abstract

For many species of passerine bird, young males acquire their song during a sensitive period when they learn songs from their paternal parents or nearby neighbors. Since young birds are most likely to learn their songs from nearby singers, regional song dialects may form. The mountain chickadees (Poecile gambeli) in the mountain ranges of Trans Pecos Texas and southeastern New Mexico are an excellent subject to study this phenomenon due to their resident status and isolation on forested mountain peaks surrounded by desert lowlands. In this study, I hypothesized that localized song dialects exist amongst the isolated mountain chickadee populations within this sky island system, that song differentiation between populations increases with geographic distance, and that song diversity is positively correlated to habitat patch size. Samples from 54 Mountain chickadees recorded in 2023 in the Sacramento and White Mountains, Gallinas Mountains, and Manzano Mountains exhibit differences in the predominant song types and song characteristics across each sky island. Chickadees in the Sacramento, White, and Gallinas Mountains deliver songs consisting of three long notes, while those in the Manzano Mountains deliver songs with two brief notes followed by a long note, another brief note, and another long note. A quadratic discriminant analysis, permutational MANOVA, and Mantel test of song and note characteristics support the hypothesis that mountain chickadees exhibit geographic song variation between these locations, while Jaccard indexes of song similarity indicated that neighboring populations share more song types than distant ones. However, more data is needed from other sky island chickadee populations to determine a relationship between patch size and song diversity.

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