METABOLIC STRATEGIES FOR WINTER SURVIVAL BY SVALBARD REINDEER

Lying and standing metabolic rates were determined for two tame Svalba rd reindeer while the animals were in their winter lethargic state dur ing January and February. Mean nonfasting metabolic rates for the 59-k g animals were 1.25 W . kg-1 for lying and 1.64 W . kg-1 for standing at rest. So the metabolic rate for standing at rest was about 1.3 time s the lying resting metabolic rate (RMR). For Svalbard reindeer the ly ing RMR was 66-78% of the values for other reindeer/caribou, and was 7 8-89% of the predicted value. The standing RMR was 44-88% of the value s from other reindeer/caribou. Total body thermal conductance was 1.95 +/- 0.17 W . degrees-C-1 for lying and 3.08 +/- 0.77 W . -degrees-C-1 for standing at rest. The daily energy expenditure during winter was estimated to be about 9654 kJ . day-1 or 112 W, and was 1. 5 times Kle iber's predicted basal metabolic rate. By remaining lying 45 % of the time rather than 35 % Svalbard reindeer may conserve the equivalent of about 15 days' energy requirement over the winter. With locomotion at 2 % of the winter daily activity budget, the Svalbard reindeer conser ve about 21 days' energy expenditure, more than that if locomotion wer e 8.2% of the budget as in caribou (Boertje 1985). Thus, their low ene rgy expenditures for lying and standing and their sedentary activity b udget may be considered energy-saving and survival strategies. It is p ossible that disturbances, which cause the animals to increase activit y, may have a detrimental effect on their overall winter energy balanc e.