10-10-2001 BLUE MOUNTAINS NSW, AUSTRALIA - EASTERN GREY KANGAROO (Macropus giganteus)

The eastern grey kangaroo (Macropus giganteus: gigantic large-foot; also great grey kangaroo or forester kangaroo) is a marsupial found in the eastern third of Australia, with a population of several million. Although a large M. giganteus kangaroo male can typically weigh up to 69 kg (152 lb) and have a length of well over 2 m (6 ft 7 in),the scientific name is misleading as the red kangaroo of the semi-arid inland is larger, weighing up to 90 kg (200 lb).

The eastern grey kangaroo was described by George Shaw in 1790 as Macropus giganteus.

Although the red is better known, the eastern grey is the kangaroo most often encountered in Australia, due to its adaptability. Few Australians visit the arid interior of the continent, while many live in and around the major cities of the southern and eastern coast, from where it is usually only a short drive to the remaining pockets of near-city bushland where kangaroos can be found without much difficulty. The eastern grey prefers open grassland with areas of bush for daytime shelter and mainly inhabits the wetter parts of Australia. It also inhabits coastal areas, woodlands, sub-tropical forests, mountain forests, and inland scrubs.

Like all kangaroos, it is mainly nocturnal and crepuscular, and is mostly seen early in the morning, or as the light starts to fade in the evening. In the middle of the day, kangaroos rest in the cover of the woodlands and eat there but then come out in the open to feed on the grasslands in large numbers.The eastern grey kangaroo mainly graze a wide variety of grasses[ compared to other species (e.g. the red kangaroo) that also include significant amounts of shrubs in their diet.

Eastern grey kangaroos are gregarious and form open-membership groups. The groups contain an average of three individuals. Smaller groups join to graze in preferred foraging areas, and to rest in large groups around the middle of the day. They exist in a dominance hierarchy and the dominant individuals gain access to better sources of food and areas of shade. However, kangaroos are not territorial. Eastern grey kangaroos adjust their behaviour in relation to the risk of predation with reproductive females, individuals on the periphery of the group and individuals in groups far from cover being the most vigilant. Vigilance in individual kangaroos does not seem to significantly decrease when the size of the group increases. However, there is a tendency for the proportion of individuals on the periphery of the group to decline as group size increases. The open membership of the group allows more kangaroos to join and thus provide more buffers against predators.