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.
Petrogale persephone (' Proserpine1 brush rock-weasel')
1 Proserpine is the Roman name for the Greek goddess Persephone.
Conway National Park, Queensland
Conway National Park is 30 km east of Proserpine. It is on the coast and overlooks the Whitsunday Passage and thus includes beaches and mangroves as well as a hinterland of lowland rainforest and woodland. The Park is accessed from Airlie Beach along Shute Harbour Road, not Conway Beach and the township of Conway. The 22,500-ha park has one bush camp accessible along a 2.1 km walking track from the Swamp Bay/Mt Rooper carpark. The camping ground has a shelter and pit toilet but no cooking facilities. There are a number of short walking tracks. The Proserpine Rock-wallaby is found in the northern end of the Park and can be difficult to see. The species was introduced to Hayman Island between 1998-2002 and a breeding population established.
Males to 10.2 kg and females to 8.1 kg. The back of the Proserpine Rock-wallaby is a dark grey with white tipping to the hairs that gives it a penciled texture and a mauve appearance after the spring moult. The head is dissected by a thin dark dorsal stripe from the back of the head to the mid-back in some individuals. A dark sooty-brown patch lies behind the shoulder. The upper part of the head is pale brown- grey and the lower part a pale grey. There is a pale white-grey facial stripe on the upper lip, which passes below the eye towards the ears. This is demarcated below by another pale grey stripe arising at the corner of the mouth and passing back to the base of the ear. The tip of the nose is black and naked. The backs of the ears are covered with very short brown-orange hairs and the insides are black with a few sparse hairs. The base of the tail is pale brown-orange that lightens in colour on its sides. The tail is initially coloured like the back but darkens to mostly black on the upper side and has a variable but short white tail tip 15 to 20 mm long that is missing in some individuals. The fore legs and the lower part of the hind legs are orange-brown. The hands, toes and distal half of the hind feet are black. The chin and throat are white and the chest cream to yellow. The remainder of undersides are pale white-grey, becoming more yellow towards the tail base and the inner hind legs. The orange or yellow highlights are variable and dull and indistinct in some individuals.
The Proserpine Rock-wallaby is likely a relict of a once more widespread ancient lineage of rock-wallabies. As such it has the smallest geographic range of any Petrogale sp. with as little as 14,500 ha of suitable habitat. As an insurance policy for the species conservation, an island population has been established in the Whitsunday Passage. Rocky habitat embedded within semi-deciduous vine thickets is preferred but the margins of rainforest and disturbed areas within forests are occupied. The choice seems to relate to diverse resources to service a broad diet in an area with significant climate variability. Shelter is found in thickets, crevices and caves as is typical of the rock-wallabies.
The diet has been well-studied and varies between the wet and dry seasons. In the wet, grass and some small herbs (forbs) make up about 60% of intake with the remainder from browse, fruits and flowers. Amongst the browse is not only tree leaves but also seedlings and small saplings. In the dry, browse increases and fallen leaves are taken from the ground with some folivory in accessible shrubs, vines and trees. Proserpine Rock-wallabies may be seen basking in the daytime but foraging is basically nocturnal. In spite of its relict population, the species seems quite hardy and gets through the dry season on Gloucester Island without free water apparently depending on moisture in the food and dew. Home ranges of 20 ha have been estimated.
The reproductive behaviour has been studied in captivity. Gestation takes 30-34 d and the oestrous cycle is 33-38 d. Birth occurs within a day of permanent pouch exit by the previous young and mating is post-partum. All macropods have a copulatory plug which includes coagulated blood and semen in grey kangaroos. The copulatory plug of the Proserpine Rock-wallaby is apparently particularly large and may act as a barrier to further mating during a female's brief oestrus and assure paternity. However, the manipulative fore-paws of macropods mean that males can pull out this plug if the female remains receptive so its function deserves further investigation. Pouch life is around 6-7 months with a further 3-6 months until weaning. Females are sexually mature by 18 months of age with males maturing later at 24 months.
The Proserpine Rock-wallaby is social and lives in groups of around 20 or more. There is pronounced sexual dimorphism with males larger than females, and males occupying larger home ranges. There is a size-related hierarchy amongst males, at least in captivity, with the largest male dominant and mating preferentially with females.
Eldridge MDB, Close RL (1997) Chromosomes and evolution in rock-wallabies, Petrogale (Marsupialia: Macropodidae). Australian Mammalogy 19, 123-135.
Nolan BJ (1997) An update of the proserpine Rock-wallaby Petrogale persephone recovery plan. Australian Mammalogy 19, 309-313.
Johnson PM, Delean JSC (1999) Reproduction in the Proserpine rock-wallaby, Petrogale persephone Maynes (Marsupialia: Macropodidae) in captivity with age estimate and development of the pouch young. Wildlife Research 21, 631-639.