Seasonally-related physiological and behavioural changes in captive Richardson's ground squirrels (Spermophilus...

1. This study reveals the interrelationship among body weight, food intake and activity for a one-year period in two different year groups of captive juvenile Richardson's ground squirrels (Spermophilus richardsoni). 2. An increase in body weight during initial captivity and during the post-hibernation period related to an increase in food intake and in activity. 3. High and constant body weights during the pre-hibernation seasons were associated with a "voluntary" reduction in food intake, a decline in standard metabolic rate and in activity. These changes occurred before changes in photoperiod and temperature. 4. Hibernation occurred in most of the food-deprived animals but, except for one individual, not in animals provided with food ad libitum.