Meeting Abstract
We examine two case studies of vocal “mistakes” produced by wild songbirds that can lead to insights into the development and function of song. Both examples occur in a species that learns its song through improvisation or invention rather than through imitation, the Grasshopper Sparrow (Ammodramus savannarum). In one case, a male of the Eastern subspecies in Maryland produced an atypical crystallized song structurally very different from normal adult song, though its duration and bandwidth were species-typical. The song resembled some elements of vocalizations produced during the plastic song phase of song development. In the second case a bird of the Florida subspecies produced a song that resembled that of another emberizid in its habitat, the Bachman’s Sparrow (Peuacea aestivalis). These cases suggest different types of learning errors that can occur under natural circumstances, and that may contribute to Allee effects in a species with small and declining populations. We tested the effects of such atypical songs on song function in the Maryland case by performing a song playback test. Results suggest that natural song learning errors may be more detrimental in intersexual contexts than in intrasexual contexts.
