MATE FIDELITY AND PARENTAGE IN CORY SHEARWATER CALONECTRIS-DIOMEDEA -FIELD STUDIES AND DNA-FINGERPRINTING

Field studies on Cory's shearwater Calonectris diomedea, which were ca rried out in a breeding colony in the Aegean Sea between 1989 and 1993 , revealed that almost all breeding mates stay together over many cons ecutive years. Mates usually changed when one partner disappeared (e.g . through death), whereas 'divorce' occurred at a rate of 2.7%. Since birds are nesting at very close quarters, the potential for extrapair copulation (EPC) and subsequent extrapair fertilization (EPF) seems to be high. Multilocus DNA fingerprints were used to determine the true parentage of 46 offspring (broods contain a single chick only) from 29 pairs (few pairs were studied in two and three successive years). The re were no cases of extrapair paternity.