Breeding biology, chick growth and provisioning of Great Shearwaters (Puffinus gravis) at Gough Island, South Atlantic Ocean
2005
Cuthbert, Richard J.
The Great Shearwater (Puffinus gravis) is the largest (860 g) and most abundant shearwater species of the South Atlantic Ocean, with a breeding population of six million pairs on the islands of Gough and Tristan da Cunha. The breeding ecology of the species was studied on Gough Island from September 2000 to May 2001. The breeding cycle of Great Shearwaters was ∼7.5 months from time of arrival to departure, with a highly synchronised return of birds to their burrows in mid-September, departure for a pre-laying exodus of ∼1 month from mid-October, and a peak of laying around 21 November. Chicks fledged by mid-May after an average rearing period of 108 days. Overall breeding success was 66%, with hatching (56%) and fledging (93%) success within the normal range for Puffinus species. Chick growth followed the normal pattern for Procellariiformes, gaining body mass rapidly to a maximum mass of ∼150% of adult mass, and then losing weight until fledging. Chicks were fed large meals (188 g) but only infrequently (every 3–4 days), with 22% of all meals delivered during daylight hours. The long interval between feeds suggests that adult Great Shearwaters could be foraging at a great distance from the breeding colonies.
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