Rock Wallaby
Photo: Courtesy of Damon Ramsey
BSc.(Zool) Biologist Guide
Rock Wallaby: Petrogale spp. There are about 15 species of rock wallabies. Many of them look very similar to each other, and before the use of genetic testing to determine species, there was were thought to be far fewer species. Different species were determined by counts of chromosomes, then confirmed by the resulting offspring of mixed species being infertile (Egerton 1997). Their geographic isolation to rocky outcrops is likely to be an important influence on previous and current speciation.
Living amongst the rocks Rock Wallabies are small kangaroos that live within rocky outcrops. They are only found in mainland Australia and some offshore islands, being absent from Tasmania and New Guinea. They are more common in the arid and tropical parts of Australia. In contrast to their agility between the boulders, they are said to be quite awkward in open country (Walker and Nowak 1985). They are rarely seen due to their rocky inaccessible habitats and the speed in which they can bound around boulders. Leaps have been measured at four meters (Walker and Nowak 1985). However, their signs are everywhere. Their small round droppings take a long time to decompose in the rocky habitat, and some of the rocks on the more used `trails' may be worn and shiny (Egerton 1997). Many of the behavioural and physical features of Rock Wallabies are a reflection of their lifestyle leaping around rocky boulders. The feet are broad and fringed with stiff fur (Walker and Nowak 1985) and heavily granulated (Triggs 1996) for grip. The claws are shorter so as to not impede movement over rock (Egerton 1997). If tracks are seen, both the relatively larger hindfeet and shorter claws can be noted and used to distinguish the tracks from other macropods (Triggs 1996). The tail is long relative to the body than in many other kangaroos. It is slender, but doesn't taper towards the end, and is often held upright to maintain balance when leaping over rocks. Their fur often matches the colour of the surrounding rocky habitat (Egerton 1997), so as some species will be light brown in sandstone, but grayer in granite, and almost black in basalt. Due to the high humidity within the rocks relative to the drier surroundings, rock wallabies do not need to drink regularly (Egerton 1997). They can also reportedly gain much of their water requirements from eating juicy bark and roots (Walker and Nowak 1985). They feed mainly on grass, but also on herbs, leaves and fruit (Strahan 1998) Rock Wallabies live in colonies within the rocky outcrops. Here they are protected from predators of the more open areas, such as eagles, dingoes and humans. However, in bad seasons they are reported to travel many kilometers from the safety of their rocky habitat (Egerton 1997). They tend to hide between rocks during the heat of the day and may bask in the open in the cooler morning or afternoon (Strahan 1998). Female rock wallabies have well-developed pouches (Walker and Nowak 1985). The mother bounds around rocks with the young locked in by the muscles of the pouch. However, once out of the pouch, the young don't follow the mother, but are left hidden within the rocks until they are fast and agile enough to keep up (Egerton 1997).
Rock Wallabies and humans Rock Wallabies were not likely ignored as a food source by the Aboriginal people. They probably took advantage of the fact that they often shared the same habitat, and that their prey followed predictable trails. The fate of rock wallabies since European settlement has been mixed. Some species have done well hidden in outcrops that are relatively inaccessible to introduced animals such as sheep and rabbits (Walker and Nowak 1985), and in areas that are difficult for humans to clear. Other species have had their numbers reduced. Some were threatened by trade in their soft fur, especially the "Yellow footed Rock Wallaby" Petrogale xanthopus. These days, foxes are thought of as one of their greatest threats (Strahan 1998). The "Brush-tailed Rock Wallabies" Petrogale penicillata were actually introduced into Hawaii in 1926 (Strahan 1998). The genus name of rock wallabies means `rock weasel'; as with other wallabies such as the pademelons, there must have been something very weasel-like about many wallabies to the early European explorers.
The Allied Rock Wallaby's: includes - Petrogale assimilis, P.mareeba, Psharmani This group of wallabies can not really be identified as separate species just by looking at their physical appearance. They were once considered races of the same species, and were only differentiated by studying the chromosomes (Egerton 1997). Thus, they form a closely related `complex' of ecologically and physically similar species that are all found in rocky habitats along the Great Diving Range in North Queensland in Australia. They are all small rock wallabies. There is a fur molt in autumn, with the hair becoming sandier in colour to match the growing `wallaby grass' found around the rocky habitats in which they live (Strahan 1998). They mate all year around. Pair bonds are probably formed between males and females (Strahan 1998). They tend to be generalist and opportunistic feeders (Strahan 1998). They eat forbs, grass, fruits, seeds and flowers (Strahan 1998) and may also approach to take handouts.
Mareeba Rock Wallaby: Petrogale mareeba The Mareeba Rock Wallaby was only really `discovered' in 1992 when it was recognized as a genetically distinct species, rather than a subspecies or race of the "Unadorned Rock Wallaby" Petrogale inornata (Strahan 1985). They are quite restricted in distribution, being found only in the Mareeba area, just west of Cairns, north to Mt.Carbine and south to Mt. Garnet. Within this area, they are found in rocky habitats, which tend to be granite boulders found in tropical open woodland.
Script: Courtesy of Damon Ramsey BSc.(Zool) Biologist Guide
Additional Rock Wallaby Photos
Additional Rock Wallaby Photos 2
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