Common Cuckoos (Cuculus canorus) Do Not Rely on Indicators of Parental Abilities When Searching for Host Nests: The Importance of Host Defenses

Abstract

ABSTRACT. There is widespread evidence that individuals within and among host populations are not evenly parasitized by Common Cuckoos (Cuculus canorus). We first investigated whether the song and nest size of a host species, the Great Reed Warbler (Acrocephalus arundinaceus), reveal information on parental abilities and level of defense against Common Cuckoos. Second, we analyzed whether female Common Cuckoos' preference for host nests is predicted by the degree of song expression and the nest size of the host. Earlier-breeding hosts built bigger nests, were more active singers, and had less rich syllable repertoires than late breeders. Host nestlings raised in a big nest received more feedings than those raised in a small nest. Host males that were active singers were paired with females that built bigger nests. All host pairs rejected nonmimetic artificial eggs, but those with a big nest were more prone to reject natural Common Cuckoo eggs. Thus, Great Reed Warbler pairs with a big nest were more willi...