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Frequency of egg and nestling destruction by female brown-headed cowbirds at grassland nests

Auk

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Abstract

Researchers have suggested that Brown-headed Cowbirds (Molothrus ater) destroy nest contents of potential hosts to induce renesting and thus enhance future opportunities for parasitism. Although cowbird destruction of passerine nests has been witnessed and surmised, few data are available on frequency of those events. We used miniature video-cameras at nests of grassland passerines and documented partial or complete destruction of eggs or nestlings by cowbirds at 7 of 132 nests monitored with cameras. At least three of the seven cases appeared to be attempts to totally destroy the nest contents; those cowbirds did not appear to be motivated by food or an intent to parasitize the nest. Three cases probably were associated with parasitism, but two involved egg removal late in incubation and the third was unusually destructive. Cowbirds were responsible for 24% of egg losses and 5% of nestling losses caused by predators. The importance of cowbirds as an agent of egg and nestling loss undoubtedly varies among sites and years, but it should not be overlooked.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Frequency of egg and nestling destruction by female brown-headed cowbirds at grassland nests
Series title:
Auk
Volume
118
Issue:
3
Year Published:
2001
Language:
English
Description:
p. 765-769
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Auk
First page:
765
Last page:
769