DISCRIMINATION OF SONG TYPES AND VARIANTS IN SONG SPARROWS

Male song sparrows, Melospiza melodia, sing highly variable songs. Tra ditionally, researchers have partitioned this variability by assigning songs to discrete categories termed 'song types', but researchers als o have recognized that songs classified as the same song type are them selves variable. Territorial playbacks were used in a habituation/reco very design to investigate whether songs sparrows perceive songs class ified as separate song types to be more distinct from one another than songs classified as variants of the same song type. Cluster analysis was used to classify playback songs as song types or variants. Playbac ks consisted of focal songs repeated for 1 h, followed by a switch to 6 min of either (1) a second variant of the focal song type from the s ame source male or (2) a second song type of the same source male. Twe lve sets of playback tapes were used in a total of 96 trials. Subjects showed habituation in the response measure (distance to the speaker) during playback of the focal songs. Response recovered for between-son g type switches, with mean distance to the speaker decreasing signific antly between the last 3 min pre-switch and the first 3 min post-switc h, and between the last 6 min pre-switch and the 6 min post-switch. Fo r within-type switches, recovery was significant when comparing only t he last and first 3 min. Recovery was significantly greater for betwee n-type switches than for within-type switches on both measures. These results suggest that in the perception of male song sparrows, differen t song types are more distinct than are different variants of a single type.