ETHOPHYSIOLOGICAL RESPONSES TO OVERWINTER FOOD SHORTAGE IN WILD EUROPEAN RABBITS

Wild European rabbits studied under seminatural conditions turned out to have about 30% lower heart rates during periods of overwinter food shortage than during periods with access to green forage or pelleted rabbit chow. Concomitant changes in the animals' metabolic rate (ADMR), body weight, blood sugar level, and foraging activity clearly indicate that this heart rate reduction is a sign of starvation due to insufficient food quality. Telemetered body temperature, on the other hand, was amazingly stable in most subjects, even during overwinter food shortage. These data are discussed with respect to nutritional requirements and possible mechanisms of energy conservation in wild European rabbits.