MEPS 224:267-282 (2001) - doi:10.3354/meps224267
Foraging strategies of shy albatross Thalassarche cauta breeding at Albatross Island, Tasmania, Australia
April Hedd1,*, Rosemary Gales2, Nigel Brothers2
ABSTRACT: The foraging zones and behaviour of shy albatross Thalassarche cauta were studied at Albatross Island, Tasmania, Australia, during the 1995/96 and 1996/97 breeding seasons, using a combination of archival recorders and satellite telemetry. Birds foraged exclusively in the neritic zone, at a maximum distance of 200 km from the colony, making wide use of continental shelf waters off northwest Tasmania. The duration of foraging trips, the distances traveled and the activity ranges of the birds (i.e. 95% isopleths from Kernel home range analyses) were greatest during incubation (2.8 d, 754 km, 24667 km2), least during chick-brood (1.1 d, 273 km, 19067 km2), and intermediate during early chick-rearing (1.8 d, 426 km, 19400 km2). At the population level, the foraging zones of the birds (i.e. the 50% home range isopleths) were highly consistent between years, overlapping by 43% during both the incubation and chick-brooding stages across 3 breeding seasons. Overall, the foraging zones of males and females were similar in both size and location. Individual birds did not return to the same locations to feed from 1 trip to the next; however, their foraging was not random. On successive trips birds maintained a constant heading from the colony, repeatedly searching the same broad patches of ocean, a degree of site fidelity maintained within a single breeding stage. They flew for 72% of the daytime and 39% of the night, and their rate of travel was significantly higher during the day. Combined with a diet predominated by prey found at or near the surface during the day, these data suggest that shy albatross are largely diurnal feeders. Nocturnal activity was strongly influenced by moon phase, with increased time spent flying and increased flight speed during full moon. Consistent traveling speeds, foraging trip durations and foraging locations across years suggest relatively stable prey availability and/or accessibility for shy albatross breeding off the northwest coast of Tasmania.
KEY WORDS: Shy albatross · Satellite tracking · Foraging · Site fidelity · Activity patterns
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