Individual recognition by song in white-throated sparrows. III. Song features used in individual recognition

Abstract

We investigated features of song important in recognition of neighbors by playing natural and altered songs to territorial male white-throated sparrows (Zonotrichia albicollis). The major pattern (ascending or descending) of notes in a song provided insufficient information for recognition, since strange songs were responded to as such, whether or not they resembled neighbors' songs in this respect. Songs consisting of only the first three notes permitted neighbor–stranger discrimination. Neighbors' songs were altered in various ways, though never beyond the normal range of variation for the population. We assumed that if features important for recognition of neighbors' songs were altered sufficiently, the birds would respond to neighbors' songs as though they were strange songs. We found that a change of more than 5 to 10% in pitch of the song, pitch of the first note, and possibly pitch change between the first and second notes interfered with recognition of a neighbor's song. In contrast, changes as great as 15% in duration of a song or of the first note had no effect on recognition. Reliance on pitch for recognition is consistent with present knowledge of natural variation in songs of individual white-throated sparrows and of auditory discrimination of birds. Features of song used in species and individual recognition are compared.