Geographic Variation in Song of Gambel's White-Crowned Sparrow

Abstract

AbstractWhite-crowned sparrow (Zonotrichia leucophrys) song varies geographically, often forming local 'dialects' in sedentary and short-distance migratory subspecies. In playback experiments males and females can distinguish this variation. Gambel's white-crowned sparrow (Z. L. gambelii) is a long-distance migrant that breeds across subarctic Canada and Alaska. Previous studies identified a wide degree of song variation within local populations of this subspecies. I compared songs recorded in Alaska and Churchill, Manitoba, and found significant differences in acoustic structure. As in other subspecies, the most prominent differences occurred in the terminal trill portion of the song. In a playback experiment to territorial males at Churchill, males gave equivalent strong responses to both Alaska and local gambelii song, significantly weaker responses to mountain white-crowned sparrow (Z. L. oriantha) song, and the weakest responses to heterospecific song. I describe a model of song recognition in which 'dialect recognition' is a component of species recognition. I conclude that as a consequence of differences in the timing of song learning, the subspecies of white-crowned sparrow may differ in the acoustic features that they attend to in song recognition. The diversity of song types at a local level within gambelii populations may interfere with recognizing song differences between populations.