Geographic Variation in the Song of the Rufous-Collared Sparrow in Eastern Argentina

Abstract

Variation in trill features of Rufous-collared Sparrow (Zonotrichia capensis) song is described in three sites located on the northeast coast of Buenos Aires Province, Argentina. There is a distinctive dialect in sites supporting natural woodlands. This dialect is characterized by slower trills with lower minimum frequencies than the one present in the open grassy fields (steppe dialect). Talar dialect is absent in a site where natural woodlands have been replaced by grassy fields and open man-made parks, suggesting that the vocal tradition changed after habitat modification. Detailed analysis reveals that talar and steppe dialects intergrade in a song cline, following the vegetational ecotone. This song cline has been stable in location and features during the last decade, even though there were no geographic barriers impairing population or cultural exchange between habitats.