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
Macropus robustus woodwardii ('Woodward's robust long-foot')
Litchfield National Park, Northern Territory
Litchfield National Park is within a 2-hour drive from Darwin along a sealed (bituminised road). The Park has many attractions including its waterfalls and natural plunge pools, abundant fauna, rich woodland flora communities including pockets of monsoon forest, and the unusual magnetic termite mounds. The park has a number of rocky outcrops and some escarpments. Waterfalls cascade over the latter and provide popular swimming holes at their base. It is amongst the rock outcrops and gentler faces of the escarpments that you are most likely to see Northern Wallaroos. They may share habitat with the Short-eared Rock-wallaby which will be smaller and more agile on the steepest cliff faces. The Park is also nominated as the best place to see the Short-eared Rock-wallaby and Antilopine Wallaroo, and Agile Wallabies are abundant.
The Northern Wallaroo is the tropical sub-species of the most widespread kangaroo, the Common Wallaroo (or Hill Kangaroo). Euros have a large naked rhinarium giving them a dark shiny ‘button nose’ like koalas and wombats. They have no facial stripe but they do have large rounded ears. Their coat is coarser and shaggier than the fine down of Red Kangaroos. Females are relatively short and small and rarely exceed 25 kg. Their coat colour varies from light grey through light tan to dark grey. Males are short but very stocky with pronounced forearm musculature when mature. They reach around 50 kg and show a similar variation in coat colour to females but are often be darker coloured than females. The underparts are lighter and the tail tip is not black. The Northern Wallaroo can be distinguished from the Antilopine Wallaroo by its less gracile form and grey rather than red coat. It also does not have the bulbous nose of the Antilopine Wallaroo and you would expect to see it more often in the escarpments than the latter. The Northern Wallaroo overlaps with the Black Wallaroo in the Arnhem Land escarpment of Kakadu National Park. It is larger and less uniformly coloured than the Black Wallaroo.
Northern Wallaroos hop on their short legs in an upright posture, which seems less elegant than Red and Grey Kangaroos on flat ground, but comes to the fore as they effortlessly bound up rocky slopes.
Habitat is the slopes and escarpments of high country. Males may travel down gullies and watercourses in arid periods of the dry season but females tend to remain in the hills. The Wet-Dry tropics are particularly rich in rock-haunting mammals and you could expect to see the Northern Wallaroo in association with Short-eared Rock-wallabies, Narbalek, Black Wallaroos, Rock Ringtail possums and Common Rock-rats. Short tussock grasses are the natural ground vegetation of these areas and well suit Common Wallaroos (cf. spinifex in many other arid parts of the range). Frequent fires encourage fire-adapted native sorghums and lower the quality of the escarpment grasslands. In Central Arnhem Land, aboriginal burning practices were examined in relation to the abundance of kangaroo scat (faecal pellets). Burning promoted use in moist habitat presumably because it stimulated re-sprouting of grasses and provided more nutrient but in rocky habitat scat abundance declined after fire. Thus frequent burning does not favour the rock-haunting species like the Northern Wallaroo although it may be flexible enough to exploit burnt areas facing some competition with Antilopine Wallaroos and Agile Wallabies.The diet of the Northern Wallaroo has been studied in sympatry with Black Wallaroos. The species are not segregated by habitat but the Northern Wallaroo is larger than the Black Wallaroo. The Northern Wallaroo as typical of the Common Wallaroo is a grass eater and consumed predominantly grass through both the Wet and Dry seasons whereas the Black Wallaroo included more browse in its dry season diet. Thus there may be some dietary segregation between the two species in sympatry with the larger Northern Wallaroo more capable of digesting dry mature grasses than the smaller Black Wallaroo.The Common Wallaroo is a continuous breeder and may have three overlapping generations of offspring - a young-at-foot, a pouch young and a diapausing blastocyst in utero. Oestrus is part-partum and males regularly check the reproductive status of females. Male dominion at a mating event is usually related to body size and the consort male may be accompanied and challenged by a bevy of importunate males. It is presumed that the Northern Wallaroo is aseasonal in breeding unlike the Antilopine Wallaroo.The Common Wallaroo is generally solitary with strong bonds only between a mother and her dependent young-at-foot. The Northern Wallaroo in sympatry with Antilopine Wallaroos near Coomallie Creek in the Northern Territory had a mean group size of 1.1 compared to the latter species 2.2 supporting the solitary nature of the Northern Wallaroo. Agile Wallabies in the same are likewise were generally solitary but did aggregate at times on favourable pasture joining and leaving such aggregations independently. No such aggregations were seen of Northern Wallaroos that tended to remain on steep sided rocky ridges with little overlap with the other two macropods. One male Northern Wallaroo was radio-tracked in this habitat and occupied a small 9.9 ha home-range confining its movements to a single ridge.
Croft DB (1987) Socio-ecology of the antilopine wallaroo, Macropus antilopinus, in the Northern Teritory, with observations on sympatric M. robustus woodwardii and M. agilis. Australian Wildlife Research 14, 243-255.
Dawson, TJ (1995) Kangaroos: biology of the largest marsupials. (UNSW Press: Sydney)
Telfer, W.R. and Bowman, D.M.J.S. (2006). Diet of four rock-dwelling macropods in the Australian monsoon tropics. Austral Ecology 31, 817-827.