Group size and activity in eastern grey kangaroos

Abstract

Eastern grey kangaroos, Macropus giganteus, graze in open-membership groups and are hunted by dingoes, Canis familiaris dingo. Kangaroos in groups of different sizes were simultaneously observed on a homogeneous pasture and their activities were recorded. All major environmental variables, except group size, were the same for all individuals. There was a strong positive correlation between group size and time spent feeding and a negative one with time spent looking around, the relationship being best described by asymptotic curves. Kangaroos in small groups were significantly more likely than those in large groups to stand upright when looking around, a posture interpreted as indicating more intense altertness.