Fidelity of Song Imitation and Stability of Dialect Songs in Brown-Headed Cowbirds

[摘要] Abstract. Temporal stability in the acoustic structure of dialect songs is a critical variable for studies of cultural evolution in songbirds. Here we report that the structure of the flight whistle song of Brown-headed Cowbirds (Molothrus ater) of the Convict dialect in the eastern Sierra Nevada of California remained essentially stable over almost 30 years. Quantitative measurements showed a minor structural change in one of four syllables and a small but statistically significant increase in duration for whistles recorded in 2006 versus 1990. Audiospectrograms of whistles recorded in the late 1970s revealed no major structural differences from the 1990 and 2006 whistles. These results are consistent with field and ontogenetic studies showing that young cowbirds copy the songs of adult males with very high fidelity, although it may take them up to two years to do so. We contrast the Convict results with those from the adjacent Mammoth dialect, in which the local whistle changed substantially over approx...

[学科分类] 动物科学

[关键词] songbirds;dialects;song sharing;cultural stability;cultural evolution;Brown-headed Cowbird;Molothrus ater