Field metabolic rates of black-browed albatrosses Thalassarche melanophrys during the incubation stage

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 (FMRat-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 (FMRon-nest) were also measured using DLW. The mean(plus-minus)SD FMRat-sea of albatrosses was 611(plus-minus)96 kJ kg ^-1 d^-1 compared to FMRon-nest of 196(plus-minus)52 kJ kg^-1 d^-1. While at sea, albatrosses spent 52.9(plus-minus)8.2% (N=3) of their time in flight and they landed on the water 41.2(plus-minus)13.9 times per day. AThe FMR of black-browed albatrosses appear to be intermediate to that of three other Aalbatross species. Based on at-sea activity, the power requirement of flight was estimated Ato be 8.7 W kg^-1 (or 4.0×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 FMRat-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.