The songs of white-throated sparrows consist of 5 notes of very pure tonal quality. In ascending song, the pitch increases substantially from Note 1 to Note 2; whereas, in descending song, pitch decreases substantially from Note 2 to Note 3. Variability in the absolute pitch of each note is considerable among birds, but much less within individuals. Analysis of the major pitch changes in these songs shows that the pitch interval (ratio of the higher to the lower frequency), a measure of relative pitch constancy, predicts the frequency of the higher note in the pitch change more precisely than does the difference between the frequencies of the two notes, a measure of absolute pitch constancy. We conclude that white-throated sparrows produce relative rather than absolute pitch constancy during the major frequency changes in their songs and suggest that pitch interval may be an important cue in species recognition.