Behavioral Ecology and Sociobiology

, Volume 41, Issue 4, pp 205–215 | Cite as

Density and extra-pair fertilizations in birds: a comparative analysis

  • David F. Westneat
  • Paul W. Sherman


Møller and Birkhead (1992, 1993) reported that extra-pair copulations (EPCs) occur more frequently in colonial than dispersed nesting birds. We comprehensively reviewed published data to investigate how breeding density affects extra-pair fertilizations (EPFs). Within species EPFs appeared to increase with density: two of three studies on colonial breeders and six of eight on dispersed nesters showed increases in EPFs with increasing density. However, comparisons among species (n = 72) revealed no evidence that EPF frequencies correlated with (1) nesting dispersion, (2) local breeding density, or (3) breeding synchrony, even when each of these variables in turn was held constant and phylogenetic relationships were taken into account via contrast analyses. Methodological and biological reasons for the disparity between observational studies of EPCs and molecular genetic analyses of EPFs are discussed.

Key words Extra-pair fertilizations Breeding density Dispersion Synchrony Contrast analyses 


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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • David F. Westneat
    • 1
  • Paul W. Sherman
    • 2
  1. 1.Center for Ecology, Evolution, and Behavior, T.H. Morgan School of Biological Sciences, 101 Morgan Building, University of Kentucky, Lexington, KY 40506-0225, USAUS
  2. 2.Section of Neurobiology and Behavior, Seeley G. Mudd Hall, Cornell University, Ithaca, NY 14853, USAUS

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