ABSTP.CT.--Thesongs of 102 male House Finches (Carpodacus mexicanus) were sampled in southern California.Additionally, songs were induced with testosterone in 10 captive females.Females sang only 1 or 2 themes, whereas males averaged 4 themes; males in each recording location shared a repertoire of similar phrases and songs.Song types sung by neighboring males were more similar to each other than to songs of more distant birds.Some females sang themes identical to male songs; others sang simpler songs with fewer syllable types.In a 5-km transect from Occidental to Montecito, four populations (identifiable by population-specific phrases in their songs) were described in a continuum, one replacing the other over a distance of 5 km.Clumped distribution of theme types suggests song development by male-male interaction, as has been reported for other passerines.California House Finches exhibited greater syllable diversity, more themes per locality, and more themes per individual than eastern birds.California House Finches did not exhibit distinct song dialects as did eastern populations; possible reasons for this difference are that eastern House Finches have fewer themes to mimic and thus learn whole songs.California House Finches are older populations with large repertoire sizes and tend to improvise by building new themes with syllables from several songs.It is also possible that California House Finches vary geographically in their tendency to share songs.Song learning in House Finches may promote individual recognition due to improvisation and theme matching by mated pairs.
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Bitterbaum et al. (1979) studied this question.