La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Parental investment and brood rearing in feral Greylag Geese Anser anser.
Auteurs :	Marion Weisser, Auteur ; Christoph Randler, Auteur
Type de document :	Article
Dans :	Ornithologischer Anzeiger (44(1) JUL 2005)
Article en page(s) :	1-8
Résumé :	Brood rearing behaviour of feral Greylag Geese (Anser anser) was observed at Max-Eyth-See in Stuttgart, Germany, during the breeding season of 2004 by M. Weisser. We aimed at testing three hypotheses: 1) division of labour between males and females is similar to that of natural populations, 2) parental investment (vigilance behaviour) declines in the course of brood rearing, and 3) parental investment is adjusted to brood size ("shared parental investment"). 10-min-sessions of focal animal sampling were used, during which the behaviour of the male, the female and the majority of the juveniles was simultaneously recorded every 15 sec. Sampling periods were adjusted to gosling age. Seven pairs were observed. Division of labour was similar to that observed in wild goose populations: males were more vigilant and females fed more. During brood rearing, vigilance decreased in both adults. Parental vigilance (mean of male and female) appeared not to be adjusted to brood size and did not differ with regard to brood size. This result might be incomplete due to slight variance in the sample or due to the adaptations to an urban environment. An average of 4.4 juveniles per pair fledged.

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