Philopatry and faithfulness to nest site in Cory's Shearwaters Calonectrisdiomedea at Selvagem Grande

Nearly fledged Gory's Shearwater Calonectris diomedea chicks at Selvagem Gr ande occasionally desert their nest sites during the night, but generally r eturn before dawn. The temporary use of other nest sites is rare and lasts less than two days. Almost all chicks from Selvagem Grande return to the is land for their first breeding attempt; very few breed at islands outside th e archipelago. On Selvagem Grande, almost half the males return to their na tive colony whereas more than 90% of females recruit to other colonies. Int er-colony movements sometimes exceed 1 km, but, if they return to their nat ive colony, both sexes settle within 20 m of their natal site. From the sec ond breeding attempt onwards, most birds of both sexes are faithful to the nest site. On average, less than 20% of birds desert their former nest site each year, with a shift of about 4 m only. Most nest shifts follow a breed ing failure or a temporary respite from breeding, and are accompanied by a switch in partners.