Flexibility of Basal Metabolic Rate in Arctic breeding Kittiwakes (Rissa tridactyla)

Abstract

Information on body mass, basal metabolic rate (BMR) and body composition were obtained From adult female kittiwakes (Rissa tridactyla) breeding on Svalbard (79 degreesN). While body mass, BMR and body composition was stable during the incubation period, both body mass and BMR decreased significantly during the chick-rearing period. Both whole-body and mass-specific BMR decreased during this period indicating that the reduction in BMR must be due to an altered metabolic intensity. Body composition analyses revealed that while most organs masses changed in parallel to total body mass, the liver showed a disproportional decrease. In a subsample of individuals, a significant relationship was also found between liver mass and BMR. The results suggest that BMR is not a species-specific character, but rather a flexible physiological parameter. with liver mass being an important determinator.