Temporal dynamics of dry-season water-hole use by large African herbivores in two years of contrasting rainfall in Hwange National Park, Zimbabwe

As the dry season progresses in arid and semi-arid ecosystems. rain-fed surface water sources become depleted, forcing most animals to concentrate in the immediate vicinity of the few remaining permanent sources of drinking water. This study investigates the temporal dynamics of use of water-holes by nine African large-herbivore species in the dry season in the semi-arid savanna of Hwange National Park, Zimbabwe, and particularly how annual rainfall influences this temporal dynamics. Two contrasting years in terms of annual rainfall were compared: 2003 (a drought -362.6 mm) and 2004 (average rainfall -695.8 mm). In 2003, water-holes were used far more intensively and the level of aggregation of herbivores at water-holes was significantly higher. The temporal dynamics of water-hole use in the dry season differed between the two years: in 2003. the peak of water-hole use started much earlier and lasted 3 mo. Elephants and grazers showed the largest difference in use of water-holes between 2003 and 2004 supporting the suggestion that browsers are less water dependent. This study suggests that annual rainfall should be taken into account when predicting the peak of the dry season.