The effect of ungulate grazing on a small mammal community in southeastern Botswana
Ungulates can reduce the quantity of food available for other herbivores in general or reduce the available cover for small mammals in particular. On the other hand, browsing and grazing may facilitate foraging by other mammals if the quality and palatability of young re-sprouting tissue is high. An exclosure experiment was set up in Mokolodi Nature Reserve, Botswana, to study ecological effects of large herbivores on the small mammal community. Specifically, we attempted to answer the following questions: 1) are population sizes and community composition of small rodents affected by the exclusion of large herbivores?; 2) if so, what changes in the environment caused by the exclusion of large herbivores are related to changes in small mammal populations?; 3) in what way do such changes in the environment affect small mammals? The populations were significantly larger in the exclosures than in the control areas. A higher number of species was also found in the exclosures. It seems that the smaller populations of small mammals in areas with large herbivores are a result of a reduction in vegetation cover. In general, the exclosures had a higher grass cover than their paired controls. This same relation also held for percentage cover of litter and dead grass.
Keywords: plant-herbivore interactions, exclosures, mark–recapture, grazing impacts