Land-use change is considered a major driver of biodiversity loss. In the western part of the Tarangire–Manyara ecosystem, we assessed large mammal species richness along a land-use gradient (national park, uninhabited pastoral area and settled pastoral- and farmland). We found the highest species richness in the national park and in the pastoral area and lowest species richness in the settled and farmed area. There was little evidence of seasonal changes in species diversity. Except for top-order carnivores, all functional feeding