Contrasting capabilities of two ungulate species to cope with extremes of aridity

Southern Africa is expected to experience increased frequency and intensity of droughts through climate change, which will adversely affect mammalian herbivores. Using bio-loggers, we tested the expectation that wildebeest (Connochaetes taurinus), a grazer with high water-dependence, would be more sensitive to drought conditions than the arid-adapted gemsbok (Oryx gazella gazella). The study, conducted in the Kalahari, encompassed two hot-dry seasons with similar ambient temperatures but differing rainfall patterns during the preceding wet season. In the drier year both ungulates selected similar cooler microclimates, but wildebeest travelled larger distances than gemsbok, presumably in search of water. Body temperatures in both species reached lower daily minimums and higher daily maximums in the drier season but daily fluctuations were wider in wildebeest than in gemsbok. Lower daily minimum body temperatures displayed by wildebeest suggest that wildebeest were under greater nutritional stress than gemsbok. Moving large distances when water is scarce may have compromised the energy balance of the water dependent wildebeest, a trade-off likely to be exacerbated with future climate change.

Post-Release Monitoring Diet Quality and Nutritional Status of Reintroduced Burchell’s Zebra and Blue Wildebeest in Maputo Special Reserve, Mozambique

The reintroduction of wild animal species into conservations areas is widely used to restore populations of species endangered with extinction. The assessment of the quality of the diet and the nutritional status of the animals is crucial to the success of herbivore reintroduction programs, given that adequate nutrition is essential to ensure the survival and fertility of ungulates. Given this, the present study investigated the quality of the diet and nutritional status of Burchell’s zebra ( Equus burchelli, Smuts 1832) and blue wildebeest ( Connochaetes taurinus, Burchell 1823) reintroduced into Maputo Special Reserve (MSR), in southern Mozambique. The study was conducted between July 2016 and June 2017, and the data were collected through direct observation, by driving a vehicle along the roads within the reserve that pass through the vegetation cover where zebra and wildebeest are known to occur most frequently. The composition of the diet and specific feature of the grass grazed by the two species, such as greenness (an indication of food quality) were assessed. Crude fecal protein and phosphorus were determined to evaluate the nutritional status of the two herbivore species. Both herbivores were pure grazers, consuming a diet composed entirely (100%) of grass. Aristida barbicollis was the principal component of the diets of both zebra and wildebeest and both species grazed almost entirely on green grass (91–100% of greenness). However, wildebeest consumed significantly more green grass (which has a better nutrient content) than zebra, which tolerated a considerably larger proportion of browner grass in both seasons. The levels of crude protein and phosphorus in the zebra and wildebeest fecal samples were not below threshold of nutritional stress recommended for large southern African herbivores, which indicates that neither the zebra nor the wildebeest populations in MSR are undernourished at the present time and that the quality of the forage found in the study area is not a factor limiting the persistence of the reintroduced populations of either species.