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 analyses) were measured in free-ranging male springbok antelope (Antidorcas marsupialis) during the three seasons of the Kalahari. Results from springbok that did not drink water during the hot, dry season indicate that they can achieve water balance without drinking if they can obtain 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 succulent. 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 independent of drinking water. During the rut, males had high energy and water requirements and lost weight because they did not eat enough food to maintain balance. During most of the year, springbok used water and energy at comparatively low rates, in common with other desert-adapted mammals. Their water-economy index also was low, indicating a conservative water metabolism. We estimated that an adult male springbok consumes ca. 504 kg (dry matter) of food/year and that the population of springbok consumed ca. 76% of the annual grass productivity within the important, dry riverbed habitats. Competition with other large grazers, and particularly with those restricted to foraging in close proximity to drinking water, probably existed during the dry years of this study.