Wagner, R. H. 1996: Why do female birds reject copulations from their mates? Ethology 102, 465–480.
Why Do Female Birds Reject Copulations from their Mates?
Article first published online: 26 APR 2010
1996 Blackwell Verlag GmbH
Volume 102, Issue 3, pages 465–480, January-December 1996
How to Cite
Wagner, R. H. (1996), Why Do Female Birds Reject Copulations from their Mates?. Ethology, 102: 465–480. doi: 10.1111/j.1439-0310.1996.tb01140.x
- Issue published online: 26 APR 2010
- Article first published online: 26 APR 2010
- Received: June 27, 1995; Accepted: December 14, 1995 (J. Brockmann)
Female birds frequently reject copulations from their mates, suggesting a conflict between the sexes. This study analyses behavioural data of socially monogamous razorbills, Alca torda, to examine whether females rejected their mates because of conflicts over fertilization or the pair bond. Among pairs, females rejected 9–70 % of their mates’ copulation attempts and prevented their mates from completing 42–100 % of successful copulations. Copulations terminated by females were half the duration of those terminated by males, and females terminated fewer first copulations than subsequent ones on the same day. These findings indicate that females were motivated to copulate less frequently and for shorter durations than their mates. The sperm competition hypothesis predicts that females reject their mates to increase the probability of being fertilized by extra-pair males. This hypothesis was not supported because females rejected extra-pair males similarly to their mates. The female-mate-guarding hypothesis predicts that females guard their pair bond by copulating frequently with their mates, thereby depriving the males of time and energy to copulate with and form bonds with other females. This prediction was consistent with a significant negative correlation between the percentage of copulation attempts that females accepted from their mates, and the number of extra-pair copulations that their mates attempted. However, this correlation was not caused by a trade-off of males copulating with their mates instead of attempting extra-pair copulation because males attempted most extra-pair copulations on days when their mates were absent. A new hypothesis is proposed, namely, that females reject their mates to test the male's commitment to provide essential parental contributions after egg-laying. The ‘testing-of-the-bond’ hypothesis is consistent with the findings but requires testing.