DIVERGENT SEXUAL RESPONSES TO DIFFERENT CATEGORIES OF FOREIGN COURTSHIP SONGS IN FEMALE BROWN-HEADED COWBIRDS (MOLOTHRUS ATER)

Abstract

Abstract Female songbirds generally have an innate ability to distinguish between con-specific and heterospecific song, and may learn to discriminate among variants of conspecific song. By observing female copulation-solicitation displays elicited by playback of perched songs and flight whistles from distant (>2,000 km) widespread populations, we assessed the extent to which responses of female Brown-headed Cowbirds (Molothrus ater) to the two categories of male courtship song depend on experience. We hypothesized that female responsiveness to flight whistles is more dependent on experience than their responsiveness to perched song, because, though both perched songs and flight whistles vary spatially, perched songs always conform to strict species-specific structural and syntactic rules. Flight whistles, in contrast, are so variable that some types may not be recognizable as conspecific vocalizations to birds that have never experienced them. The species-wide structural similarities of perched songs make...