Kangaroos are the world’s largest marsupials and the largest species of macropod. Large males can exceed 1.8 m when standing fully erect and reach a body weight of 90 kg. Adult females are always much smaller in size, reaching body weights of 30 - 40 kg.
Kangaroos are shy herbivores, active at dawn and dusk. They graze on grasses and green herbage, the abundance of which determines the proportion of females that breed and the survival of their young. Kangaroos are bipedal which means that they hop on their hind legs at speeds of up to 48 kilometres per hour for several kilometres and at 20 kph over very long distances. Grey and red kangaroos hop in characteristically different ways. The grey hops with a more vertical body axis while red kangaroos hop with a more horizontal body axis.
Both species have a long tail, that acts as a counterbalance when hopping and a prop when grazing. Kangaroos are gregarious, living in small family groups with the adult female the matriarch, and other group members females and young, usually related to her. The male kangaroo joins the group for a few days when females are fertile but separates from the main mob in winter when breeding females are unlikely to come into oestrus. Mature males sometimes form loose associations with other males, which are not long lasting and vary from year to year.