Seed predation by nocturnal rodents in an African savanna ecosystem

Abstract

The small mammal community in Acacia savanna consists of three omnivorous nocturnal rodent species, Mastomys natalensis, Saccostomus campestris and Aethomys chrysophilus, which eat varying proportions of seed in their diet. From a seed removal experiment, it was found that rodents preferentially selected Acacia tortilis seeds. The annual Acacia seed consumption by rodents in a South African savanna ecosystem was analysed by using estimates of rodent population densities, diet composition, seed predation by captive rodents and published estimates of field metabolic rates. Total seed consumption was estimated to represent 1,64,1% of the annual seed crop of A. torlilis, 0,7-0,9% of the annual seed crop of A. nilotica and 9,3-25,0% of the annual seed crop of A. karroo. Granivory of A. nilotica seeds by rodents may have a negligible effect upon seedling recruitment. However, rodent predation of A. torlilis and A. karroo seeds may have important implications on seed survival and later seedling recruitment.