La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Day-night variation in spatial activity of wintering Cory\'s Shearwaters Calonectris diomedea recorded by satellite tracking
Auteurs :	Dean Hashmi, Auteur ; Dietrich Ristow, Auteur ; Peter Berthold, Auteur ; Ulrich Querner, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (122(5) 2001)
Article en page(s) :	273-277
Résumé :	The exclusively nocturnal activity of many procellariiforms at the breeding sites may have evolved due to costs at the colony and/or benefits at sea during daylight. It is therefore possible that the activity patterns within and outside the breeding season differ. Based on satellite tracking data we report higher indices of travel speed during the day of two Cory\'s Shearwaters (Calonectris diomedea) wintering in the tropical eastern Atlantic. In one case, at least, we can exclude that this difference is caused by biases of location quality and path duration. Spatial activities at sea, regarding differences between day and night, appear to be similar during incubation and in winter. The inclusion of low quality locations allows to use a much larger number of paths for the study of spatial activity, but several biases may impede the interpretation of data of such heterogeneous quality.

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