Individual Stability, Local Variability and the Cultural Transmission of Song in White-Crowned Sparrows (Zonotrichia Leucophrys Nuttalli)

Abstract

The songs of 306 territorial male white-crowned sparrows were recorded between 1975 and 1983 in two study areas in San Francisco, California. Nestlings were banded and 47 sons whose father's songs had been recorded acquired territories. Some fathers had more than one son who acquired a territory. The songs of 263 territorial neighbours of the sons were also recorded. In addition, there were 32 females for whom both the father's and the mate's songs were available. The songs that were sung on the two study areas differed in a number of qualitative and quantitative aspects. For each area, there was change across years, in qualitative composition of song types, as well as considerable variability in the properties of the songs within dialect areas throughout the course of the study. There were 49 instances in which the song of a territory holder was recorded for more than one year. These individuals exhibited considerable stability of song across years. The song types of sons and fathers and of sons and neighbours were compared; Analysis of these songs indicated that some sons sang the song of the father, some adopted a song similar to that of the neighbours, and some had song with idiosyncratic elements that, in a few cases, remained in the population during succeeding generations. These data provided no support for the hypothesis that sons learned song preferentially from the father: there was no tendency for the quantitative characteristics of the songs of sons and fathers to be more similar than those of sons and neighbours, and when a father had two sons whose song was known, there was little tendency for the three songs to resemble one another. Finally, the songs of a father and his daughter's mate did not tend to resemble one another, indicating that females of this species do not choose as mates males that sing the same song as their father's. These results suggest that variability in transmission of song types may play a role in individual recognition, which in turn might aid a male to acquire a territory.