The Cost of Extra-Pair Fertilizations to Female Red-Winged Blackbirds

It has recently become apparent that females of many species of birds often copulate with, and produce young sired by, males other than their social mates. Understanding the adaptive significance of this behaviour requires knowing whether extra-pair matings entail any cost to females. We investigate...

Full description

Saved in:
Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 1994-12, Vol.258 (1353), p.315-320
Main Authors: Weatherhead, Patrick J., Montgomerie, Robert, Gibbs, H. Lisle, Boag, Peter T.
Format: Article
Language:English
Subjects:
Animal nesting
Bird nesting
DNA fingerprinting
DNA probes
Female animals
Fertilization
Male animals
Mating behavior
Parentage
Reproductive success
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:It has recently become apparent that females of many species of birds often copulate with, and produce young sired by, males other than their social mates. Understanding the adaptive significance of this behaviour requires knowing whether extra-pair matings entail any cost to females. We investigated nest success relative to paternity in red-winged blackbirds (Agelaius phoeniceus) over 5 years and found that nest success declined as the proportion of nestlings that was sired by extra-pair males increased. Nest defence against potential predators is the principal form of paternal care in this population. Males defended nests less vigorously when they contained nestlings sired by other males, suggesting that the lower success of those nests was a consequence of reduced paternal care. Nests with extra-pair young were more successful when the true father was a local resident, suggesting that resident males may defend other males’ nests if they have sired some of the young. Our results indicate that females must realize substantial improvement in offspring fitness if they are to compensate for the cost of extra-pair fertilizations.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.1994.0179