Geographic Variation in Song and Dialects of the Puget Sound White-Crowned Sparrow

Abstract

Geographic variation in song, and song dialects were studied [spectrography] in breeding populations of the migratory subspecies Zonotrichia leucophrys pugetensis. Using morphology and sequencing of elements, 2 widely distributed song themes were distinguishable. At zones of secondary contact between these 2 song types a few birds were bilingual. Syllables in the medial portions of the songs tended to re-occur in mosaic fashion over hundreds of miles. With few exceptions, syllables in the terminal trills were characteristic of groups of adjacent populations thus permittimg the distinction of 6 dialect areas. Variation within populations in 5 of these dialects was low, reminiscent of the dialects of Z. l. nuttalli. Song dialects of Z. l. nuttalli are more local in distribution than those in Z. l. pugetensis. A few Z. l. nuttalli may occasionally learn partial or complete songs from overwintering Z. l. pugetensis. Based on song morphology dispersal across water barriers was considered more frequent in Z. l. pugetensis than in Z. l. nuttalli. In contrast to Z. capensis, no correspondence was found between song dialect and specific habitat types in Z. l. pugetensis. The possible use of song as a tool in the study of migration in Z. l. pugetensis was treated. Possible relevance of song variation to the genetic structure of populations of Z. l. pugetensis along the Pacific coast and in Puget Sound was discussed.