Song Switching in Mate Attraction and Territory Defense by Western Meadowlarks (Sturnella neglecta)

Many passerines have a repertoire of song types that appear to be functionally equivalent. Previous work suggested that in such species the act of switching between song types in itself might be a territorial signal, a sexual signal, or both. If switches are frequent enough, they may also serve to advertise a male's repertoire size, which is thought to signal male quality. We studied variation in song switching by western meadowlarks through the season and during interactions with conspecifics. Males repeat each song, to form a bout, before switching to the next song type. Males repeat each song type fewer times during mate attraction and when their female goes out of sight. They also switch song types at the onset of two types of territorial interactions and sexual interactions. Thus song switches are apparently used in both mate attraction and territory defense. However, males switch through their entire repertoire only in certain situations. At other times, the timing of a male's song switches, and what songs he sings, might be more important than repertoire size itself in determining his success in intra‐ and intersexual interactions. 1991 Blackwell Verlag GmbH