BREEDING CYCLE OF THE CANE PETREL DAPTION CAPENSE AT NELSON ISLAND, ANTARCTICA

Timing and duration of the breeding cycle of the Cape petrel Daption c apense were studied during two breeding seasons (1990/1991 and 1991/19 92) at Nelson Island, South Shetland Islands, Antarctica. In 1991/1992 the copulatory period extended over 53 days, with median date and a p eak about 28 and 19 days respectively, before the median date of layin g. Laying began 85 days after arrival, with mean (= median) date on 2 December (SD = 2.5 days). The distributions of laying, hatching and fl edging dates showed a similar degree of synchrony and did not differ b etween years. Incubation and chick period were equally long (46 days), the former being less variable (coefficient of variation = 2.8% and 4 .6%, respectively). Mean completed nesting cycle (92 days) was about 2 days shorter at Nelson Island than elsewhere and tended to shorten as the breeding season progressed. Its mean length represented 86% of th e whole nesting period (107 days), which in turn represented 56% of th e period of continuous colony attendance. Timing and duration of nesti ng stages did not differ between colonies or sets of nests subjected t o various levels of disturbance.