The tammar wallaby (Macropus eugenii), also known as the dama wallaby or darma wallaby, is a small macropod native to Western Australia. The Tammar Wallaby was formerly widespread in south-western Western Australia. Though its geographical range has been severely reduced since European colonisation, the tammar remains common within its reduced range and is listed as "Least Concern" by the International Union for Conservation of Nature (IUCN). It has been introduced to New Zealand and reintroduced to some areas of Australia where it had been previously eradicated. Skull differences distinguish tammars from Western Australia, Kangaroo Island and mainland South Australia, making them distinct population groups or possibly different subspecies.
About the size of a rabbit, the tammar is among the smallest of the wallabies in the genus Macropus. Its coat colour is largely grey. The tammar has several notable adaptations, including the ability to retain energy while hopping, colour vision and the ability to drink seawater. A nocturnal species, it spends nighttime in grassland habitat and daytime in shrubland. It is also very gregarious and has a seasonal, promiscuous mating pattern. A female tammar can nurse a joey in her pouch while keeping an embryo in her uterus. The tammar is a model species for research on marsupials, and on mammals in general.
One of the smallest wallaby species in the genus Macropus, the tammar wallaby features a small head and large ears with a long tail, thick at the base. It has dark grey-brown upperparts with paler grey highlights, rufous on the sides of the body and limbs, particularly in males, and pale grey-buff underparts. The tammar wallaby exhibits significant sexual dimorphism, with the maximum recorded weight in males being 9.1 kg (20 lb) and maximum recorded weight in females is 6.9 kg (15 lb). The body length is 59 to 68 cm (23–27 in) in males and 52 to 63 cm (20–25 in) in females. Both males and females are about 45 cm (18 in) in height. The tails of males range from 34 to 45 cm (13–18 in) and those of females from 33 to 44 cm (13–17 in).
As with most macropods, the tammar wallaby moves around by hopping. This species has a hopping frequency of 3.5 strides per second, with a stride length of 0.8 to 2.4 m (2.6–7.9 ft). When hopping, proximal muscles at the knee and hip joints generate most of the power for each leap, which are delivered by multi-joint muscles at the ankle. As it lands, the energy of the jump is converted into strain energy made when its leg tendons are stretched. As it leaps back off the ground, the tammar can recover much of this energy for reuse though elastic recoil.
The amount of energy stored in the tendons increases with the animal's speed and the weight of the load it is carrying. This is particularly helpful for mothers carrying young, and explains why tammars can increase their hopping speed without using more energy. The tammar shares this characteristic with other plains-dwelling macropods like the red kangaroo. By comparison, rock wallabies, such as the yellow-footed rock-wallaby, have traded efficient energy saving for greater tendon thickness; an adaption for steep rocky terrain as it allows them to leap higher and lowers the risk of their tendons rupturing.