Song sharing in two populations of song sparrows (Melospiza melodia).

Abstract Sharing song types with immediate neighbors is widespread in birds with song repertoires, and sharing songs may confer a selective advantage in some cases. Levels of song sharing vary between dierent geographical populations of several bird species, and ecological dierences often correlate with dierences in singing behavior; in particular, males in migratory subspecies often share fewer songs than males in resident subspecies. The song sparrow (Melospiza melodia) appears to ®t this pattern: resident song sparrows in western North America generally share 20±40% of their repertoire (of about eight songs) with each neighbor, while migratory subspecies from eastern North America often share 10% or less. We compared song sharing in two populations within a single subspecies of song sparrow (M. m. morphna) in Washington State. These populations, separated by only 120 km, nonetheless dier in migratory tendencies and several other ecological and life history variables. We recorded complete song repertoires from 11 male song sparrows in a highelevation, migrating population at Gold Creek in westcentral Washington, and compared them to two samples (n=15 and n=36) from a coastal, resident population at Discovery Park, Seattle, Washington. Despite major dierences in habitat, population density, and migratory tendencies, song sharing among Gold Creek males was as high as that among Discovery Park males. In both populations, sharing was highest between immediate neighbors, and declined with distance. We conclude that at the within-subspecies level, neither migration nor population density aect song sharing in song sparrows, a song repertoire species