Setonix brachyurus
quokka

This single species inhabits southwestern Australia, including Rottnest Island and Bald Island.

On islands, the quokka occurs in a variety of habitats. Despite its preference for densely vegetated, moist conditions, the quokka survives in large numbers on Rottnest Island in a harsh, seasonally arid habitat where the low vegetation affords little cover, and potable water is limited. As a result of limited water on Rottnest Island, those populations farthest from sources of fresh water suffer the highest mortality. On the mainland, they seem restricted to dense vegetation in swamps around dry sclerophyll forest. The preferred shelter is a thicket or some other shady place where the animal can avoid the summer heat. An individual returns to the same shelter every day through most of the year, but sometimes changes sites.

The Quokka is one of the smallest wallabies. Distinct features include short and fairly coarse hair with coloration generally brown with lighter underparts. The ears are short and rounded, the nose is naked and the tail is sparsely furred and short.

Females are polyestrous, with an average estrous cycle length of 28 days. In captivity they are capable of breeding throughout the year, but in the wild anestrus occurs from August to January. Nondelayed gestation is 26 to 28 days. Litter size is usually one, and one young is successfully reared each year. One day after the young is born, the female mates again and then embryonic diapause begins. If the young in the pouch should die within five months, the embryo resumes development and is born in 24 to 27 days. If the first young lives, the embryo degenerates when the female enters anestrus. Under good conditions the second embryo can resume growth after the first young is successfully raised. The young leaves the pouch between 175 to 195 days old, but will return if alarmed or cold. Maturity is reached at approximately 389 days for males and 252 for females.

On Rottnest Island the populations are organized into family groups. Adult males dominate the family and also form a linear hierarchy among themselves. Although the hierarchy is usually stable, on hot summer days the adult males fight intensively for the best shelters. Availability of such sites is the main factor in limiting the populations. There is little evidence of territoriality, and groups of 25 to 150 individuals may have overlapping home ranges, especially during the summer when many groups concentrate around available fresh water. At night, when quokkas emerge to feed, they makes runways and tunnels through dense grass and undergrowth. They hop on their hind legs when moving quickly and do not use their tail as a third prop when moving slowly, unlike kangaroos and large wallabies. They are terrestrial, but can climb up to 1.5 meters to obtain food.

At night the quokka emerges from its shelter to feed mainly on a variety of grasses.

Until the 1930's the qoukka was very common in coastal part of the mainland of southwestern Australia. Subsequently it disappeared, except for a few small colonies on the mainland and the two relatively numerous island colonies. There is concern for the populations living on Rottnest island because of development of the island for recreational purposes. The quokka is listed as endangered by the USDI.