BASAL METABOLIC RATES OF NORTH-ATLANTIC SEABIRDS

Basal metabolic rates (BMR) were measured for 11 species of North Atlantic seabirds, ranging in size from the Kittiwake Rissa tridactyla to the Gannet Sula bassana. BMRs for all species were higher than those predicted from the allometric equations of Lasiewski and Dawson (1967), Aschoff and Pohl (1970) and Ellis (1984), The equations of Ellis (1984), incorporating a latitude correction, and of Bennett and Harvey (1987), involving deviations by seabird families from a general avian trend line, gave predictions for BMR which were closer to, but respectively lower and higher than, those observed in this study, BMR for seabirds in Scotland (55-60 degrees N) is described by the equation: BMR (kJ/d) = 2.30W(0.774), The principal sources of variability in BMR amongst seabirds and the selective forces shaping the differences between seabirds and most other birds with lower BMRs remain unclear but deserve further study.