Does Cory's Shearwater breed every yearor is there evidence for a sabbatical?

RISTOW D., SWATSCHEK I. and WlNK M.

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Abstract:

A colony of Cory's Shearwater (Ca/onectris d. diomedea) was studied for severa l years on a rocky island off Crete. Care was taken to distinguish breeding birds. including unsuccessful breeders, from the non-breeding population. From yearly retrap data of breeding birds it is concluded that they make a breeding attempt every year and do not take a sabbatical. This result differs from the finding that the Atlantic subspecies borea/is shows a sabbatical frequency of 7"10 (Mougin et al. 1985).