Foraging location and range of white-chinned petrels Procellaria aequinoctialis breeding in the South Atlantic

The foraging range and principal feeding areas of White-chinned Petrels breeding at South Georgia were determined using satellite telemetry. Foraging trips during incubation lasted 12–15 days and covered 3000–8000 km and 2–11 days and 1100–5900 km during chick-rearing. Adults covered less distance per day during chick-rearing (71 km) than during incubation (91 km) but the proportion covered at night (47%) was the same. Mean (31–34 km/h) and maximum (80 km/h) flight velocities were similar during both periods of the breeding season and during day and night. Between incubation shifts, White-chinned Petrels travelled to the Patagonian shelf; during chick-rearing they foraged more extensively. Most locations were between 30° to 55°W and 52° to 60°W around South Georgia/Shag Rocks and south to the South Orkney Islands. Diet samples from known foraging locations suggested birds fed mainly on krill and squid. They caught the squid Brachioteuthis? picta and Galiteuthis glacialis around Shag Rocks/South Georgia and also at sites close to the South Orkney Islands; Illex argentinus on the Patagonian shelf. Dispersal of adults after breeding failure was south to the South Orkney Islands then west to the Falkland Islands. This study confirms that breeding White-chinned Petrels are amongst the widest-ranging of seabirds; they may minimise competition with other Procellariiformes in the South Atlantic by their more extensive foraging range. The nature and extent of their range also brings substantial risk of high mortality rate in South Atlantic long-line fisheries.

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