ENERGY, WATER, AND FOOD USE BY SPRINGBOK ANTELOPE (ANTIDORCAS-MARSUPIALIS) IN THE KALAHARI DESERT

Field-metabolic rates and water-influx rates (both measured via doubly -labeled water) and diet composition (rumen contents, plant sample ana lyses) were measured in free-ranging male springbok antelope (Antidorc as marsupialis) during the three seasons of the Kalahari. Results from springbok that did not drink water during the hot, dry season indicat e that they can achieve water balance without drinking if they can obt ain plant food containing at least 67% water. Springbok may accomplish this by selecting flowers, seeds, and leaves of shrubs (mainly Acacia mellifera and A. hebeclada) before dawn, when these foods are most su cculent. Springbok ate mostly grass during the hot seasons if drinking water was available, but, in the cold, dry season, their selection of succulent shrub leaves (mainly A. mellifera) apparently made them ind ependent of drinking water. During the rut, males had high energy and water requirements and lost weight because they did not eat enough foo d to maintain balance. During most of the year, springbok used water a nd energy at comparatively low rates, in common with other desert-adap ted mammals. Their water-economy index also was low, indicating a cons ervative water metabolism. We estimated that an adult male springbok c onsumes ca. 504 kg (dry matter) of food/year and that the population o f springbok consumed ca. 76% of the annual grass productivity within t he important, dry riverbed habitats. Competition with other large graz ers, and particularly with those restricted to foraging in close proxi mity to drinking water, probably existed during the dry years of this study.