Abstract
Most social carnivores live in open habitats such as the savanna. I review the theories on the effect of habitat on group formation, then present results of a study on the social, yet forest-dwelling, mongoose Crossarchus obscures, also known as the kusimanse. I radiotracked and observed C. obscures at Tiwai Island Wildlife Sanctuary in Sierra Leone, West Africa. The kusimanse was found to be diurnal and insectivorous. Mongooses slept approximately 13 m high in trees and changed sleeping sites nightly. Group sizes were similar to those seen for savanna mongooses, ranging from four to seven adults, and composition appeared to be stable. The evolution of group formation in this forest carnivore is discussed.Observations at Tiwai revealed that kusimanses may scent-mark to increase foraging efficiency, or bookkeep. Animals that bookkeep should mark while foraging and should be able to recognize the freshness of placed odors. Scents can also serve to advertise information, such as the identity, sex, or familiarity of the scent depositor. I examined the scent-marking behavior of C. obscures at the National Zoological Park, Washington, DC. Observations revealed no association between marking and foraging. Mongooses instead allomarked and marked in situations associated with aggression. Experiments revealed that kusimanses react differently to scents depending on the relatedness of the scent-provider. Scents therefore serve at least an advertisement function.