Philopatry in Cory's shearwater Cawnectris diomedea in Malta

Abstract

Philopatry is the return to the natal colony by young animals. This depends on the ability of the young to navigate back to its breeding grounds and to remember characteristics of the natal colony. This is particularly so in colonial birds such as Proceilariiformes (Warham 1990). This behaviour has been found to occur also in Cory's shearwater Calonectris diomedea (Jouanin, Raux & Zino 1977, Ristow et al. 1990, Thibault 1993). In the Maltese archipelago, the Cory's Shearwater breeds on the two main islands, Malta and Gozo and on the small islet of Filfla. The single egg is laid in caves, crevices and fissures in the vertical limestone cliffs and amongst boulder and rubble screes accumulated along ledges and cliff bases (Cachia-Zammit and Borg 1986- 1987). At present the breeding population is estimated at about 7000 pairs (pers. obs.).