General information

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 Australia and a dozen or more in New Guinea.  Some of the smaller species, such as Yellow-footed Rock-Wallabies, Burrowing Bettongs, accompanied Pig-footed and Golden Bandicoots, Bilbies and possibly Hairy-nosed Wombats into extinction with the advent of pastoralism. However, the largest species remain in much of their original range with the grey kangaroos expanding inland as grazing habitat increased and coastal habitat was lost in clearance for agriculture. The defining feature of the kangaroo family is that they are the largest vertebrates to hop (both currently and from what we know from palaeontology).

 

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.

Species

Yellow-footed Rock-wallaby (Queensland)

Petrogale xanthopus celeris ('yellow-footed rock-weasel')

Best place to see

Idalia National Park, Queensland

Idalia National Park is located 113 km south of Blackall in the central west of Queensland. For an Outback location, it has an exceptional diversity of macropods with seven species to potentially see. The park has dense mulga woodlands and escarpments of the Gowan Range where Yellow-footed Rock-wallabies can be found (best place to see Queensland sub-species). The park includes the Black-striped Wallaby and the Bridled Nailtail Wallaby and is nominated as the best place to see these species. Thus in the 144,000 ha extent of this large Outback park you can tick of three species on the 'best-place-to-see'. You can also view Red Kangaroos, Eastern Grey Kangaroos, Common Wallaroos and Swamp Wallabies.

The Park has a campground but users need to be self-sufficient including potable water. The roads may be impassable in wet weather. There is a range of other accommodation in Blackall and surrounds.  In addition to macropods, the park has a high diversity of bird species including plum-headed finches and both grey-crowned and Hall's babblers. The topographical diversity, headwaters of Bulloo Creek, gorges and floodplains provide habitat for a diverse flora which includes 15 species of native fuschia (Eremophila spp.).

Identification

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.

Habitat

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). They 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 Queensland population is in a summer 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.

Foraging behaviour

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. 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.

Reproductive behaviour

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 (summer in Queensland). 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.

Social organisation

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.

Further readings

Clancy TF, Close RL (1997) The Queensland rock-wallabies. An overview of their conservation status, threats and management. Australian Mammalogy 19, 169-174. 

Eldridge MDB, Close RL (1997) Chromosomes and evolution in rock-wallabies, Petrogale (Marsupialia: Macropodidae). Australian Mammalogy 19, 123-135.

Eldridge MDB (1997) Restriction analysis of mitochondrial DNA from the yellow-footed rock-wallaby, Petrogale xanthopus: Implications for management. Wildlife Research 24, 289-294.

Sharp A (1997) The use of shelter sites by yellow-footed rock-wallabies, Petrogale xanthopus, in central-western Queensland. Australian Mammalogy 19, 239-244.

Sharp A (1997) Insights into the dispersal patterns of Yellow-footed rock-wallabies, Petrogale xanthopus. Australian Mammalogy 19, 229-238.