Temporal variation of predation on rodents and shrews by small African forest carnivores

Abstract

Analysis of 904 small carnivore scats collected over a two-year period in a seasonal forest in the south-western Central African Republic yielded the remains of 732 shrews, rodents (<1 kg), and bats comprising at least 34 species. Most scats belonged to the long-nosed mongoose, Herpestes naso, the numerically dominant carnivore in the study area. Shrews were the principal small mammal prey with respect to number of individuals and frequency of occurrence. The mean monthly frequency of occurrence of shrews was 21.7% and of small rodents (<100 g) was 20.8%. Both shrews and small rodents occurred significantly more often in scats collected during dry season months, and live-trapping of rodents over a 22-month period revealed similar peaks in availability. In contrast to many mammalian carnivores, shrews did not appear to be used as an alternative prey source: not only did consumption levels of both prey types fluctuate in synchrony, but the availability of rodents apparently had no effect upon the likelihood of including shrews in the diet. Preferential use of small mammals by long-nosed mongooses was tested for the 10 rodent species for which abundance indices were calculated. Mongooses preyed selectively on several rodent species (Praomys spp., Deomys ferrugineus, Stochomys longicaudatus, and Grammomys rutilans), while the most common rodent in the study area, Hylomyscus spp., was found in scats at lower frequencies than expected. In accordance with the habitat specificities of these ‘preferred’ rodent prey, it is suggested that mongooses and perhaps other small carnivores were foraging in micro-habitats characterized by higher-than-average vegetation understorey thickness where the simultaneous rate of encounter with arthropods, their main prey, and shrews was apt to be high.