THE ECOLOGY OF ASOCIALITY IN NAMIBIAN LEOPARDS

Data on the ecology of leopards (Panthera pardus) from north-eastern N amibia are presented and discussed in terms of the possible costs and benefits of solitary behaviour. In an area of low leopard density, whe re individuals lived alone, both males and females occupied large home ranges, (male = 210-1164 km(2); female = 183-194 km(2)). Despite reso urce and reproductive advantages in maintaining exclusive ranges, the degree of range overlap both between and within sexes was substantial. Average overlap between males was 46% and between females 35%. The co st of dispersal appeared high as all three marked sub-adults died, and most recorded mortalities were of sub-adults. Females with dependent young showed a significant increase in per capita food intake compared to single females and males. Higher foraging success by females with cubs was revealed through two energy expenditure parameters (kg/km tra velled/day and kg/hunt/day). Differential food intake between females with cubs, single females and males can be explained partly by differe nces in day ranges, body size and costs of parental care. Females shar ed 27% of their food with cubs and the costs of sharing food does not appear as high as previously suggested. Inter-specific competition ove r food and the defence of carcasses is suggested as an important cost to group living. Leopard kills were visited by other large carnivores (12%) but food loss was minimal (2%). Leopards successfully avoided co nflict with inter-specific competitors by dragging and hiding kills in thick vegetation. We argue that solitary and secretive behaviour enab les leopards to avoid the costs of defending carcasses against larger and gregarious carnivores.