The influence of nest site characteristics on frequency of use and breeding success in the Cory’s Shearwater Calonectris diomedea

Mougin J. L., Mougin M.C.



Abstract:

In the Cory’s Shearwater Calonectris diomedea borealis of Selvagem Grande (30°09’N, 15°52’W), information was collected for 15 consecutive years on frequency of use and breeding success at 529 nest sites, the physical characteristics of which were measured or coded as ranked variables. Nest type and presence of material outside the nest site were found to have significant effects on both parameters but there were no effects of location, density, vegetation cover or type of floor. Cory’s Shearwaters being faithful to their mate and nest site, the frequency of use of a nest site is likely to be more dependant on the length of pairings and on the hazards of repairings than on nest qualities. Breeding success is also likely to depend on the qualities of the breeders more than on those of the sites.