Standard Metabolic Rate of Polar Bears under Simulated Denning Conditions

Abstract

The metabolic rate of three adult female polar bears (Ursus maritimus) was investigated under simulated denning conditions. Experiments were conducted during the winter, using a metabolic chamber as a simulated den. Ambient laboratory temperatures ranged from -10 to -35 C. Adult female polar bears were given the opportunity to enter the den of their own volition. Metabolic measurements were obtained by immobilizing the study animals and moving them into the respiration chamber. The study animals were in the den for a minimum of 1 wk prior to the measurement of oxygen consumption. A total of 50 metabolic measurements were obtained. The average standard metabolic rate for the study animals was reduced by 25% from expected values. The lowest observed metabolic rate averaged about 50% of predicted values for basal metabolism. The bears were held in the simulated den from 27 to 59 days. Weight loss for the three female bears averaged 0.70 kg/day.