Spatial Pattern of Song-Type Sharing in Male Bachman's Sparrows in South Florida

Abstract - Song-type sharing is common within populations of songbirds and often varies among individuals depending on the geographical distance between territories due to differences in song-learning strategies and natal dispersal behavior. Comparing spatial patterns of song-type sharing may allow us to infer song-learning strategies and dispersal behavior for any given species or population. Song learning and dispersal are unknown for Peucaea aestivalis (Bachman's Sparrow), an endemic songbird of the southeastern United States that is declining throughout much of its range and is considered to be near threatened. Our objective was to compare the number of song-types shared among male Bachman's Sparrows to make inferences about song development and dispersal. From 2016 to 2019, we recorded male sparrow songs in 3 different sites in South Florida, and determined song-type repertoires and song-type sharing among males within and between sites by visually comparing individual song spectrograms. Repertoire size varied among individuals and sites. Within sites, sharing did not decline with distance; between sites, sharing correlated with geographic distance between males, with song-type sharing greater at closer distances and lower at farther distances. These data suggest that Bachman's Sparrows may have an extended song-learning period and typically attempt short-distance dispersals from natal areas but disperse farther if suitable and vacant territories are not available nearby.