Ring-tailed Rock-wallaby

Generally grey back, and white underparts; yellow arms, legs and tail, darker towards the extremities. Blackish line down the back of the neck and spine; white strips down either side, across the knee and on each cheek. Upper surface of the tail conspicuously ringed. Tail long and only slightly tapered, with a crest of longer hairs along the upper extremity.

Head/body length: 480-600 mm; tail 570-700 mm; females slightly smaller than males.

Weight: 6-8 kg.

This is the largest rock-wallaby species and today its range is restricted mainly to the Flinders Ranges of South Australia, with remnant populations in the Gawler Ranges and the ranges north of Olary, stretching through to the Barrier Ranges of western New South wales. A smaller and much rarer sub-species P. x. celeris occurs in the Grey Range of southwestern Queensland.

Yellow-footed rock-wallabies are a colony species, which as far as is known once occurred in groups of up to 200-300 animals. Nowadays groups of 70 or more are extremely rare. Their preferred habitat is rocky cliff-sides, with crevices and shelter for protection from the high temperatures which can reach up to 50ºC in the shade during summer.

They are herbivorous animals and browsers rather than grazers, that is, they eat shrubs and herbs rather than grasses. Their diet is reasonably non-selective, although they avoid species known to be high in poisonous alkaloids, such as Sennas and some of the Solanum species. Even so, they eat parts of some of these non-preferred species at times of extreme drought.

Yellow-footed rock-wallabies have the remarkable ability to drink up to about 11% of their body weight in approximately seven minutes. This enables them to capitalise on runoff from infrequent summer thunderstorms instead of having to rely on creekbed scrapes. Larger macropods living in the same area, such as red kangaroos and euros, dig creekbed scrapes which enable them to drink water considerably less saline than what is available in the adjacent creek. Wallabies never dig their own but will drink from existing ones if they are there. Wallabies will drink water up to a salinity of about 17,000 ppm (parts per million) (compared with sea-water which is about 35,000 ppm), but during the summer, evaporation often causes the salinity of the creek water to exceed 25,000 ppm.

As feed becomes scarce during the summer months, part of the wallaby colony may disperse. Mating can occur while they are dispersed since a female is able to come into oestrus a few days after an encounter with a male. Gestation is about 31 days, and the young then is in the pouch for approximately five months before it leaves for the first time. This is followed by an 'interim' pouch life (the period from when the young initially leaves the pouch until it is permanerntly out) of about 40 days.

Once the wallaby young has left the pouch, it gets left in a 'safe' spot among the rocks while its mother goes off to feed on her own. Consequently the young is unable to accompany its mother when she goes off to drink. Instead the species has evolved a system which probably is unique among mammals whereby in addition to suckling, the young is able to obtain fluids by direct mouth-to-mouth transfer from its mother.

It is not known how long they may survive in the wild, but captive animals in zoos have lived for up to 14 years. It also appears that with wild wallabies, mortality is greatest just after the young has left the pouch.

Predators include the wedge-tailed eagle, dingo and carpet python, but to-day the most significant predator is the introduced European fox. Feral cats also take young.

Yellow-footed rock-wallabies are uncommon but not endangered, and they are not included in the (1995) ANZECC List of Threatened Australian Vertebrate Fauna. However, they are a fully protected species, and may not be taken from the wild.

Mainly in the Flinders Ranges of South Australia, but also in a number of Zoos, in Australia and overseas.

They can jump vertically about 2½ times their own height, but achieve much greater heights by 'cannoning' off upright surfaces.

Peter Hornsby &

Email: psyp-hor@psychology.adelaide.edu.au