La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Prelaying exodus of Cory's shearwaters (Calonectris diomedea borealis) on Selvagem Grande
Auteurs :	Christian Jouanin, Auteur ; F. Roux, Auteur ; J. L. Mougin, Auteur ; J. C. Stahl, Auteur
Type de document :	Article
Dans :	Journal of Ornithology (142(2) APR 2001)
Article en page(s) :	212-217
Langues:	Anglais
Résumé :	We stayed on the Portugese island of Selvagem Grande, 30 degrees N 16 degrees W, 300 km south of Madeira and 200 km north of Tenerife, from 9 May to 3 June 1991 in order to study the prelaying exodus in Gory's Shearwaters (Calonectris diomedea borealis) and its connection with the colony attendance cycles described earlier. Laying took place on 1.5 June +/- 3.4 days. During the preceding weeks males and females of Gory's Shearwater show very different attendance patterns. Females are absent for 19 +/- 4.8 days at minimum. Absences of males are much shorter and also much more variable. They last 7.9 +/- 6.0 days (coefficient of variation 76%, as against 12% in females). The first incubation stint of the males is badly synchronised with the laying: the delay between laying and the start of the males' first stint may amount up to one week, without compromising the breeding success. Two well marked attendance peaks have been observed, separated by an interval of

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