Seasonal levels of fat and protein reserves of snowshoe hares in Ontario

Abstract

Neutral lipid and protein levels were measured in snowshoe hares collected from a dense population at Kirkland Lake, Ontario, during the summer of 1980 and the winter and spring of 1981. The potential metabolic support provided by the oxidation of neutral lipids and protein was calculated from these values. The fat levels of hares were low, 30 g (2.5% of the body weight), and showed little variation by gender or season. Carcass protein levels were approximately 20% of the wet carcass weight in both genders and did not vary seasonally. These reserves together represent about 4 days' resting metabolic support during winter, 4 to 5 days' support under spring conditions, and 6 days' support under summer breeding conditions. The weight of selected major skeletal muscles and organs did not vary seasonally in either gender, indicating that hypertrophy and proteolysis were not occurring in this population. These metabolic reserves would not buffer chronic dietary inadequacies during winter existence and reproduction, and snowshoe hares must adopt a foraging strategy which maintains energy and nitrogen balance on a very short-term basis.