Kangaroos are marsupials and belong to the Family Macropodidae (i.e. big feet) that is grouped with the Potoroidae (potoroos, bettongs, rat-kangaroos) and Hypsiprymnodontidae (musky rat-kangaroo) in the Super-Family, Macropodoidea. This comprises around 50 species in
The Rock-wallabies (Petrogale spp.) is the most diverse genus amongst the living macropods with 16 species ranging from 1 to 12 kg in size. They are found across mainland Australia and on some recently separated offshore islands but not on the Bass Strait Islands, Tasmania or New Guinea. The species diversified from a common ancestor about 4 million years ago and their closest affinity to other macropods is with the Tree-kangaroos. Diversification of species occurred in two waves. The first gave rise to the Short-eared Rock-wallaby, the Monjon, the Narbelek, the Yellow-footed Rock-Wallaby and the Proserpine Rock-wallaby. The second was about a million years ago and lead to species that are not all morphologically distinctive like those along the Queensland seaboard. All Rock-wallabies favour habitat with rocky outcrops and slopes, cliffs and gorges or are found on boulder piles and escarpments especially in the wet-dry tropics. Their ability to scale precipitous rock faces in leaps that appear to defy gravity comes from adaptations to the feet and tail. The feet are short relative to the majority of macropods that inhabit flat ground. The pads are thick, spongy and highly granulated so that they compress on the rock surface and maximise grip. The tail is long and cylindrical with little taper and great flexibility. The tail acts as a counterbalance and rudder in rapid hopping across uneven surfaces and allows changes of direction in mid-air.
Yellow-footed Rock-wallaby (South Australia & New South Wales)
Petrogale xanthopus celeris ('yellow-footed rock-weasel')
Brachina Gorge, Flinders Ranges National Park, South Australia
The Flinders Ranges National Park is about 450 km north-west of Adelaide. The 95,000-ha Park is located between the townships of Hawker and Blinman. The visitors centre is in Wilpena Pound. The campground at Wilpena has full facilities with powered sites, toilets, showers, fuel, phone, ATM, internet access, store, swimming pool, bar and restaurant. There is also the Wilpena Pound Resort which offers motel, chalet and self-contained units.
Brachina Gorge is an important refuge for the Yellow-footed Rock-wallaby and they are readily seen on the slopes of the gorge before twilight. The Gorge is traversed by 20 km self-guided vehicle trail that interprets 130 million years of geological history. The trail is best travelled from east to west, commencing at the Brachina Gorge/Blinman Road north of Wilpena Pound. A geological map and more detailed information on the Brachina Gorge Geological Trail is available from the Wilpena Pound Visitor Centre. The Gorge has a number of bush camp sites with pit toilets and fireplaces.
Individuals weigh up to 12 kg in a weight range of 6-12 kg. The Yellow-footed Rock-Wallaby has long, soft and silky fur emerging from a dense and dark grey underfur. The back is grey. The face and crown of the head are grey with a yellow wash. The white cheek strike is well defined and offset by a black streak running anteriorly from the eye. The ears are long and yellow and highlighted at the base of the inner sides by a white edging. There is a well-defined black dorsal stripe that runs from between the ears to the middle of the back. The sides are strikingly marked. A triangular brown patch behind the elbow is bordered by a white lateral streak that runs down the body to the hip. A second brown patch tops the knee and is bounded by a white patch. The abdomen is white and the arms, legs and feet are a uniform yellow. The end fingers and toes terminate in brown. The tail is particularly striking and has alternating bands of dark brown and yellow that becomes a uniform brown towards the tip. The tail terminates in a well defined crest of black hairs. The entire underside of the tail is brown-white.
Yellow-footed Rock-wallabies have a disjunct distribution which has been further fragmented by localised extinction as a result of skin-hunting, ecological transformation for pastoralism, and a consequent wave of introduced competitors (goats) and predators (foxes and cats). Most of the NSW population is extinct and the remaining strong-hold is in SA. The rock-wallabies are typically found in steep rocky gorges or outcrops dissected by fissures and caves, and emergent rock piles. The habitat is semi-arid to arid with low unpredictable rainfall and high summer temperatures The southern population is in a winter rainfall area that experiences frequent drought. The low productivity of their habitat is reflected in much larger home ranges than the rock-wallabies of the east coast with home-range estimates ranging from 24-200 ha.
The diet is a combination of grass, small herbs (forbs) and browse according to availability. Browsing increases during dry times. They are well-adapted to an arid environment with some populations surviving without free water for parts of the year. Females may carry water back to parked young-at-foot and regurgitate it to be lapped from their mouth. The sympatric Euro digs soaks in sandy creeks with a solid rock underlayer and these may also be used by the rock-wallabies. The two macropods share rocky habitat and overlap in diet but competition with feral goats is far more detrimental to the rock-wallabies. Foraging commences late afternoon and carries through the night. They may travel several kilometres to find forage and/or water. Basking in the daytime may occur in cool winter weather.
Breeding can occur throughout the year but some concentration of births (and permanent exit of young from the pouch) can be found when rainfall is most effective (spring after winter rainfall in southern Australia). The gestation period is around 32 d with a post-partum oestrus. Dispersal between colonies is rare and so there is a degree of inbreeding without obvious detriment.
Colonies can be large and include as many as 100 individuals. Extensive radio-tracking and genetic study suggest little dispersal between colonies and so a high degree of site fidelity. Males are more mobile than females and this presumed leads to some genetic exchange between colonies and reduces the likelihood of close relatives mating.
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Copley PB, Robinson AC (1983) Studies on the Yellow-footed Rock-Wallaby, Petrogale xanthopus Gray (Marsupialia: Macropodidae) - II. Diet. Australian Wildlife Research 10, 63-79.
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