Intraspecific egg destruction in marsh wrens: a study of mechanisms preventing filial ovicide

Marsh wrens, Cistothorus palustris, attack the nests of other birds, including conspecifics. The tendency of wrens to attack conspecific nests raises the question: what prevents breeding individuals from destroying their own offspring? In this study the mechanisms that prevent filial ovicide (i.e. the destruction of eggs by parents) are examined. The results suggest that male filial ovicide is prevented by the presence of a female in the nest area, which presumably inhibits the male's ovicidal tendencies. In addition, incubating females aggressively exclude males from their breeding area, thereby further reducing the threat to their nest. Female filial ovicide is prevented through the inhibition of intraspecific nest-destroying behaviour in breeding females and through the ability of individual females to recognize their own nest site and nest. Differences between the intraspecific nest-destroying behaviour of male and female marsh wrens may reflect different reproductive strategies of the two sexes.