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 species commonly called the ‘kangaroos’ are the result of an arbitrary division of the Macropodidae based on a hind foot longer than 250 mm. The kangaroos then comprise six species of which the best known are the Red Kangaroo (Macropus rufus) of the arid heartland and the Eastern Grey Kangaroo (M. giganteus), the latter being Skippy's species. The Eastern Grey Kangaroo has a broad latitudinal distribution up the eastern part of Australia from northern Tasmania to Cape York. Its close relative, the Western Grey Kangaroo (M. fuliginosus) has a southerly and westerly distribution form western NSW and Victoria through South Australia to Western Australia. The Common Wallaroo has the broadest geographic distribuion of the kangaroos and forms a cline of subspecies across the continent but wallaroos are not found in Tasmania. The remaining two kangaroo species are less well-known and include the Antilopine Wallaroo (M. antilopinus) from the
Western Grey Kangaroo (Mainland)
Macropus fuliginosus melanops ('sooty long-foot')
Gawler Ranges National Park, South Australia
The Gawler Ranges National Park is 163,500 ha of ancient volcanic rocky hills with some old dune ridges in the southern part. The Park has few services and so provides a wilderness experience with a high degree of self-sufficiency required by visitors. The habitat is diverse and includes dramatic gorges and bluffs and spinifex grassland. The flora (225 species) and fauna (18 mammals, 126 birds, 33 reptiles, 3 frogs) are likewise diverse. Amongst the mammals, yellow-footed rock-wallabies can be seen as well as the Western Grey Kangaroo. The Park is about 6 hours drive north-west of Adelaide off the Eyre Highway.
F The sexes differ in size in a similar range to Eastern Grey Kangaroos but the mature males have a distinctive curry-like odour. This has lead to the common name of 'stinker' in some parts and an aversion to killing this species for human consumption.
Western Grey Kangaroos tend to be in the more shrubby areas and Eastern Grey Kangaroos on the grassland. Typical habitat is scrub or mallee in the heart of their range in South and
Of these 'refugees', Western Grey Kangaroos are more abundant than Eastern Grey Kangaroos in the arid rangelands where the species overlap. In both western NSW and northern
All the large kangaroos are grazers with a preference for summer grasses and winter forbs (small herbs) where they overlap in the sheep rangelands of Western NSW. Thus there is potential for dietary competition between the species. Different micro-habitat preferences tend to segregate the species with Red Kangaroos predominantly in the most open and treeless plains, Euros in the hills, Eastern Grey Kangaroos in the riparian strip along major creeks and drainages, and Western Grey Kangaroos amongst tall shrubs and acacia thickets. Of the four species, the Western Grey Kangaroo takes the most shrub and browse. Grey kangaroos, especially males, have relatively long fore-arms compared to the Red Kangaroo and Wallaroos. A large male Western Grey Kangaroo with a height approaching two metres and a reach of another half a metre can easily browse on low acacias like the Elegant Wattle (Acacia victoriae) and are regularly seen to do so. As browsing increases this wattle produces larger spines as a deterrent to mammalian herbivory. This interaction, akin to Gerenuk (a long-necked browsing antelope) on the African savannahs, suggests browsers did not fully disappear with the extinction of megafauna many thousands of years ago. The capabilities of the Western Grey Kangaroo, which like some of the large browsing kangaroos of the past is relatively short-faced, has been overlooked in a general model that the extant fauna is solely grazers.
In grazing trials in Western Australia, Western Grey Kangaroos will browse acacia seedlings but tend to avoid species with high tannin content like Eucalypts. More grass-like species (e.g. Allocasuarina, Viminalia, Xanthorrhoea) were preferentially browsed down. Selection of forage in Western Grey Kangaroos was towards high energy content with avoidance of tannins and high salt loads. Nitrogen (protein) is rarely limiting in their diet.
The reproductive biology of Eastern and Western Grey Kangaroos is very similar. However, Western Grey Kangaroos do not show diapause and so only have two dependent generations of young (one in the pouch and one at foot). The pouch must be permanently vacated for the female to mate again.
Western Grey Kangaroos in the woodland refuges in the WA wheat belt, show a decline in fertility from about 8 years so that few 12-year-old females breed. Population sizes may thus remain very stable but the generality of these results to other parts of the range is not known.
Females and their kin are the core of the mob as in Eastern Grey Kangaroos. Males may segregate into different areas during the non-breeding period but this has not been well studied in the arid zone. The Western Grey Kangaroo seems to have an undeserved poor reputation amongst pastoralists who may refer to them as 'black bastards'. However, their behaviour is as equally fascinating as the other three species and their resilience has been proven by their persistence in small woodland refuges amidst broad-acre crops.
F Part of this adaptability is their varied diet and capacity to browse. Thus look out for instances of Wester Grey Kangaroo reaching up into the canopy of a tall shrub are small tree, pulling down a branch and cropping the growing tip. You male also see rather large juveniles continuing to associate with their mother. In general, the grey kangaroos have a longer period to weaning than the other large kangaroo species. However, if a mother loses a pouch young she may allow her previous and now large juvenile to suckle in harsh times as she will have to mate again to produce a new pouch young since diapause is absent in this species. Thus even resource is used and this emboldens this species to come into human habitation to jump the fence and crop the lawn and roses. This rich diet in times of drought is often supplemented by eating cardboard if boxes are left outside.
Arnold GW, Weeldenburg JR, Ng VM (1995) Factors affecting the distribution and abundance of western grey kangaroos (Macropus fuliginosus) and euros (M. robustus) in a fragmented landscape. Landscape Ecology 10, 65-74.
Arnold GW, Steven DR, Weeldenburg J (1989) The use of surrounding farmland by western grey kangaroos and their impact on crop production. Australian Wildlife Research 16, 85-93.
Dawson, T.J. (1995). Kangaroos: biology of the largest marsupials. (UNSW Press: Sydney)
Parsons MH, Lamont BB, Davies SJJF, Kovacs BR (2006) How energy and coavailable foods affect forage selection by the western grey kangaroo. Animal Behaviour 71, 765-772.