Notes on the breeding biology of the Cory's shearwater in the Maltese islands

Abstract

The Cory's Shearwater Calonectris diomedea, is a common breeding visitor to the Maltese islands, nesting along suitable sea cliffs In Malta and Gozo, and on Filfla. The colony on Filfla breeds in cavities in boulder and rubble slopes, while other colonies are situated mainly along the south and south-western coasts of the islands in sheer cliff faces {Sultana & Gauci 1982). Due to their position it is very difficult to observe the birds at their nesting sites. However, a few accessible nesting areas can be reached in some of the colonies, and the following work was carried out in 16 such localities during the years 1983-1986. These sites vary from single accessible nests situated on the upper parts of cliffs, to whole Ledges situated on cliff faces. Along these Ledges there is a combination of boulders, crevices, caves and vegetated parts. Each area may hold from 1 to 10 accessible nests as well as other breeding pairs which nest in deeper crevices, making their observations impossible. Altogether an average of about 46 nests were under observation annually.