La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Cuckoo tricks with eggs and chicks.
Auteurs :	Nicholas Barry Davies, Auteur
Type de document :	Article
Dans :	British Birds (95(3) March 2002)
Article en page(s) :	101-115
Résumé :	The sight of a small bird feeding a young Common Cuckoo Cuculus canorus, even as the cuckoo grows to ten times its own body weight, is astonishing. Why are the hosts apparently being so stupid? Do they accept cuckoo eggs and chicks because they have limited capabilities, and so will never evolve perfect defences? Or could hosts be gradually improving their defences in a continuing evolutionary arms race? In this paper, these questions are discussed in the light of recent evidence from field observations and experiments, and from molecular genetics. Hosts' rejection of foreign eggs has led to the evolution of cuckoo specialisation and wonderful host-egg mimicry, yet hosts never reject cuckoo chicks, even though they look so different from their own young. Why? Experiments reveal how the cuckoo chick's extraordinary begging calls 'manipulate' the hosts into treating it as if it were a whole brood of their own hungry young.

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