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Cultural evolution and long-term song stability in a dialect population of Brown-headed Cowbirds

Author:
  • Adrian L. O'Loghlen
  • Vincenzo Ellis
  • Devin R. Zaratzian
  • Loren Merrill
  • Stephen I. Rothstein
Publishing year: 2011-05
Language: English
Pages: 449-461
Publication/Series: Condor
Volume: 113
Issue: 2
Document type: Journal article
Publisher: Cooper Ornithological Society

Abstract english

Knowing the extent to which the acoustic structure of songs is temporally stable is essential to understanding how cultural evolution affects song dialects in oscines. The acoustic structure of the most prevalent variant of the flight-whistle song recorded from male Brown-headed Cowbirds (Molothrus ater) in the Mammoth dialect (Mammoth Lakes, California) from 2005 to 2009 differed significantly and consistently from whistles recorded in 1989 and 1978-1985. The most common whistle variant in the 2005-2009 sample had structural features absent from whistles described in the earlier studies and overall was produced at a consistently lower acoustic frequency. Besides the emergence of this new variant sometime between 1989 and 2005, the prevalence of other variants of the whistle also changed from 1978 to 2009. Changes reported in other studies of cultural evolution in oscines have been based on lower-level structural elements (notes and syllables), whereas we found that entire songs appear to have evolved as cultural units or memes. We discuss possible mechanisms as to how these changes may have occurred. Despite these changes, the Mammoth whistle still retained the same basic three-syllable structure it had 31 years ago. This stability is notable because of the potential for extreme variation in whistle structure exemplified by the distinct whistles of nearby dialects in the region.

Keywords

  • Brown-headed Cowbirds
  • Cultural evolution
  • Cultural stability
  • Molothrus ater
  • Song dialects

Other

Published
  • ISSN: 0010-5422
Vincenzo Ellis
E-mail: vincenzo [dot] alexander_ellis [at] biol [dot] lu [dot] se

Visiting research fellow

MEMEG

Sölvegatan 37, Lund

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