Adaptation to Life in the Desert in the Brown Hare (Lepus capensis)

Adaptations to life in the desert were studied in brown hares (Lepus capensis) from the Negev Desert of Israel. For comparison, brown hares from a temperate region in southern France were included in the study. All animals sustained themselves on dry alfalfa hay. The desert hares, however, required, on the basis of their specific metabolic weight, only 75% of the amount of food consumed by the European hares, and their digestive capacity was superior. Resting metabolic rate of the desert hares was 61% of the value recorded in the European hares, and their lower critical temperature was higher. Rate of water turnover was 124 ml kg082 day−1 in the desert hares, only one-half of the value recorded for the European hares. The desert hares were able to drink salt (NaCl) solutions up to a concentration of 6%. Their maximal urine concentration was 4,470 mosmol kg−1. The maximal concentration of the salt solution consumed by the European hares was 2.5% and their maximal urine concentration was 2,500 mosmol kg−1.