La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Aggregate dispersion of birds after encountering a predator: experimental evidence
Auteurs :	J. T. Forsman, Auteur ; M. Monkkonen, Auteur ; J. Inkeroinen, Auteur ; P. Reunanen, Auteur
Type de document :	Article
Dans :	Journal of Avian Biology (29(1) MAR 1998)
Article en page(s) :	44-48
Langues:	Anglais
Résumé :	Animals may join flocks to gain protection against predation. In this experiment we investigated how predation risk affects the spatial distribution of forest birds during breeding time. We manipulated the perceived risk of predation by showing stuffed avian predators and by playing the warning signals of some of the passerine species in experimental areas. The spatial distribution of the bird individuals in both experimental and control areas was investigated by censusing birds and marking the locations of ail individuals on maps both before and after the simulated appearance of a predator. We predicted that the distances between heterospecific individuals would be reduced in the experimental areas compared with those in control plots because of a perceived increased risk of predation. After predator presentation individuals in experimental areas were closer to heterospecifics than in control areas. Predation risk is one possible cause of clumped distribution of species and mixed-species foraging flocks in boreal breeding bird communities.

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