BROWN-HEADED COWBIRDS IN EASTERN AND WESTERN NORTH AMERICA SHOW SIMILAR USE OF COURTSHIP SONGS IN COPULATION CONTEXTS

Abstract

Abstract Past work with captive Brown-headed Cowbirds (Molothrus ater) has suggested geographic variation in the relative importance females place on the two categories of male courtship song, flight whistles and perched songs. However, audio-recorded copulation sequences showed that western M. a. obscurus (California) and eastern M. a. ater (Maryland, Oklahoma and Missouri) males gave both song categories immediately before and during most sequences in nature, matching previously reported data for the third subspecies, M. a. artemisiae. Thus field data provide no evidence for geographic variation in song use during mating. Because female lordosis responses to flight whistles in captivity can be negated by certain research methodologies, unlike perched song responses, flight whistle responsiveness appears to be more dependent on experience. In all regions, males sang at higher rates prior to and during copulation than in other contexts, a distinctive manner of vocalization that may influence female mating...