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

Godman's Rock-wallaby

Petrogale godmani ('Godman's rock-weasel')

Best place to see

Lakefield National Park, Queensland

Lakefield National Park is best known for its lagoons and wetlands and so attracts birdwatchers. A vast floodplain forms in the Wet season when the Normanby, Morehead and North Kennedy rivers and their tributaries join. The water eventually drains north into Princess Charlotte Bay. During the Dry season, rivers and creeks shrink back to large permanent waterholes, lakes and lagoons.  These water bodies concentrate a diversity of animals, particularly waterbirds. The Park has a rich and diverse landscape that includes coastal estuaries, mangroves and mudflats; wetlands; grasslands and woodlands covering the vast floodplains; and sandstone hills and escarpments in the south. The last form habitat for Godman's Rock-wallaby. The Park is accessed from Laura, about 5-6 h drive from Cairns, along the Peninsula Developmental Road. There is also 4WD access from Cooktown along the Battle Camp Road.

The Park has other macropods including Antilopine Wallaroos,  Agile Wallabies, Eastern Grey Kangaroos, Northern Nailtail Wallabies and Swamp Wallabies.

Closer to Cooktown (25 km south) , Godman's Rock-wallaby can be seen in Black Mountain (Kalkajaka) National Park.

Identification

Males to 5.2 kg and females to 4.3 kg. The Cape York Rock-Wallaby and Godman's Rock-wallaby are generally similar and share a number of external characteristics with the Unadorned and Allied Rock-wallaby. Most Cape York and Godman's Rock-wallabies are more yellow-brown on the limbs, head and around the base of the tail than any of the species.  Godman’s rock wallaby has a faint dark stripe across the side of the face beginning at the nose and passing through the eye to the base of the ear.  The face-stripe is  bounded below by an indistinct yellow one.  A  narrow dark brown stripe dissects the head from about the eye level to the back of the head or the upper  back.  The upper side of has a dark tip and the lower half of the ear is pale yellow-brown.  The  ear is bounded by a narrow and yellow-white strip.  There is a brown patch behind the shoulders followed by a pale cream-brown stripe to the posterior.  The undersides are a pale yellow to grey-yellow.  The individual hairs have a grey-brown base tipped with white to yellowish.  Some individuals specimens have a short white central chest patch.  In most individuals, the distal third to half of the tail is grey-white, formed from some dark hairs with a much larger number of white to pale yellow ones.  In some individuals almost the entire tail is grey-white and in others it is all dark like the Unadorned Rock-wallaby.  Mareeba Rock-wallabies at the contact zone with Godman's rock wallaby sometimes have a grey-white tail tips.  The tail of Godman's Rock-wallaby and the Cape York Rock-wallaby has little or no terminal brush.

Habitat

The type specimen of Godman's Rock-Wallaby was collected at Black Mountain in 1922. The species is patchily distributed and abundance has fluctuated. The colouration blends well with the lichen-covered boulders in its habitat where is rests in rocky refuges and emerges at night to feed in the surrounding woodland and vine forest. Little further is known about the ecology of the species and it is presumed to be similar to the better studied Allied Rock-wallaby to the south.

Foraging behaviour

The diet of Godman's Rock-wallaby has not been studied. In general Rock-wallabies are opportunistic and generalist feeders eating mainly forbs and browse from shrubs and trees, some grass, and seasonal items like fruit, seeds, flowers and insect larvae in the tropics.

 

Reproductive behaviour

Godman's Rock-wallaby is presumed to follow the reproductive pattern of other North Queensland Rock-wallabies. The best studied of these, the Allied Rock-wallaby, has an oestrus cycle of 29-34 d, post-partum oestrus, embryonic diapause, a pouch life of 6-7 months, with weaning at 11 months. Breeding is continuous but proportionally more young are born in the late Dry season than the Wet season.

 

Social organisation

Rock-wallabies are typically social and live in colonies varying from a few individuals to over 100. In the Allied Rock-wallaby as an exemplar of the North Queensland Rock-wallabies, long-lasting stable relationships form between a male and one or two females. These individuals rest together and groom each other and expel other individuals from their range. They forage together at night but cuckoldry occurs because genetic studies show that the male does not have paternity of all the bonded female's offspring.

 

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 (1992) Taxonomy of rock wallabies, Petrogale (Marsupialia: Macropodidae). I. A revision of the eastern Petrogale with the description of three new species. Australian Journal Of Zoology 40, 605-625.

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