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Résumé :
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Field metabolic rates (FMR) and activity patterns of black-browed albatrosses Thalassarche melanophrys were measured while at sea and on nest during the incubation stage at Kerguelen Island, southwestern Indian Ocean. Activity-specific metabolic rates of five albatrosses at sea (FMR(at-sea)) were measured using doubly labeled water (DLW), and by equipping birds with wet-dry activity data loggers that determined when birds were in flight or on the water. The metabolic rates of four birds incubating their eggs (FMR(on-nest)) were also measured using DLW. The mean+/-SD FMR(at-sea) of albatrosses was 611+/-96 kJ kg(-1) d(-1) compared to FMR(on-nest) of 196+/-52 0 kg(-1) d(-1). While at sea, albatrosses spent 52.9+/-8.2% (N = 3) of their time in flight and they landed on the water 41.2+/-13.9 times per day. The FMR of black-browed albatrosses appear to be intermediate to that of three other albatross species. Based on at-sea activity, the power requirement of flight was estimated to be 8.7 W kg(-1) (or 4.0 x predicted BMR), which is high compared to other albatross species, but may be explained by the high activity levels of the birds when at sea. The FMR(at-sea) of albatrosses, when scaled with body mass, are lower than other seabirds of similar body size, which probably reflects the economical nature of their soaring flight.
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