SEASONAL PATTERNS IN BODY-MASS, BODY-COMPOSITION, AND WATER TRANSFER RATES OF FREE-RANGING AND CAPTIVE BLACK-TAILED DEER (ODOCOILEUS-HEMIONUS-SITKENSIS) IN ALASKA

Body mass, body composition, and water transfer rates were determined over a continuous 2-year period in nine free-ranging Sitka black-tailed deer (Odocoileus hemionus sitkensis). Body masses showed a cyclical pattern, declined 14-31% between October and March, and were best described by a five-parameter, biologically based regression model. The amount of mass lost by black-tailed deer over winter depended on the peak body mass attained during fall. During winter, animals used 70-82% of their body fat and 10-15% of their protein reserves. Body fat was preferentially mobilized at rates 2.3-11.6 times higher than protein. Because of the higher energy content of fat, fat accounted for 83-92% of the catabolized energy. Water transfer rates varied seasonally with average summer values approximately four times those of winter; lactating deer had significantly higher rates of water transfer than nonlactating animals. Seasonal changes in all of the above parameters for wild deer were greater than those for eight deer of the same age in captivity.