Song sequence discrimination in the black-capped chickadee (Parus atricapillus).

Captive black-capped chickadees (Parus atricapillus) were presented with normal and altered versions of their species-specific "fee bee" song, to determine how note type, number, and sequence affect recognition. The number of perch changes and vocalizations (analyzed separately) given in response to playback did not differ reliably as a function of song type, whereas latency to first vocalization after playback did. In an initial experiment using two-note songs, birds vocalized sooner to songs beginning with fee than with bee and to fee bee than to fee fee. In a second experiment, birds were presented with shortened (single note), normal, and lengthened (three note) songs each consisting of a single-note type (either fee or bee). Habituation slowed responding to altered songs but not to fee bee over three test sessions. Results from the first session suggest that chickadees distinguished single fees and three-note songs from normal song, single fees from single bees, and two-note songs from three-note songs. Results from the third session suggested that chickadees distinguished normal song from any of the altered songs. The internal representation of conspecific song in the chickadee thus distinguishes between fee and bee notes, contains information about note order, and is sensitive to note number. The pattern of responses is consistent with a model of recognition based on note-by-note integration of individual decisions about song structure.