Relative pitch recognition in white-throated sparrows, Zonotrichia albicollis

Abstract

White-throated sparrows maintain a species-specific constant pitch interval (ratio of the higher to the lower frequency) during the pitch change between the first note (phrase 1) and the remaining notes (phrase 2) of ascending song. The interval may be an important source of relative pitch information about pitch change and thus, species identity over the broad absolute pitch range of white-throated sparrow songs. This study assessed the contribution of pitch interval perception, while controlling the absolute pitch of the notes. Using one phrase from each of four birds (A, B, C and D), two songs (AB and CD) with normal pitch intervals were created, such that phrases B and C were at the same absolute pitch. These same phrases were used to construct a third song with a reduced interval (CB) and a fourth song with an increased interval (AD). In playback tests, songs with normal pitch intervals elicited significantly more approach and song responses than songs with either reduced or increased intervals. The results suggest that white-throated sparrows are sensitive to the relative pitch features in conspecific song, independent of the absolute pitches of the song phrases.