Sex differences in habitat use by African elephants (Loxodonta africana) in the Okavango Delta, Botswana: is size really the deciding factor?

摘要

Many sexually dimorphic mammals show sexual segregation of habitat use. We studied habitat selection and use by male and female elephants in the Okavango Delta, and males of different ages and therefore sizes, to assess whether size was a driving force behind any sex differences in habitat selectivity. There was variation in habitat choices, with males preferring island vegetation and mopane woodland and avoiding grassland/floodplain and Terminalia woodland; females showed no selection for or against most habitats other than selecting for mopane woodland in the rainy season. Male habitat choice changed dramatically during the dry season, when resources were most limited and there was the least sexual difference in habitat selection. Females were more selective in the flood season, when access to resources was restricted. Contrary to other studies and the forage selection hypothesis, males showed greater habitat selectivity than females, but age, and therefore size, did not affect their habitat selection. Whilst our data suggested that males were superior competitors, we could not discount that females excluded males from preferred habitats. In the Okavango Delta, habitat selection by male elephants may be more dependent on social groupings, and hence the decisions of others, than individual size and energetic requirements.