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
Common Wallaroo (Euro)
Macropus robustus erubescens ('robust long-foot with a ruddy nape')
Mutawintji National Park, New South Wales
Mutawintji National Park was returned to the traditional aboriginal owners in 1998 and is co-managed with the Mutatwintji Local Aboriginal Land Council. The Park and its associated Historic Site has a rich cultural history with extensive Aboriginal rock art. The core of the Park is the rugged Bynguano Range with spectacular and colourful gorges harbouring rock pools and dissected by red gum lined creek beds. Red Box is found on the hills with Belah and White Cypress woodlands out into the plains. A detailed geological map is available for this Park. The hills particularly suit the Euro which in the past shared this habitat with Yellow-footed Rock-wallabies. The latter species is much diminished but a remnant population persists and is protected in the Bynguano Ranges. Red Kangaroos can be seen out on the plains along with small populations of Eastern and Western Grey Kangaroos. The diverse habitat supports about 170 species of birds including many transient water birds. There are about 46 species of reptiles including many rock-haunting species.
The Euro is the arid-zone 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 distinguished by a rufous-brown nape and may often be darker coloured than females. The underparts are lighter and the tail tip is not black.
Euros 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.
The Euro is a hill-dweller and so occupies the slopes and ridges, using rocky overhangs and shallow caves as shelter in summer. Males sometimes follow more densely vegetated drainage channels out onto the plains in drought. Thus Euros are most common on the hills of various highly eroded ranges across arid and semi-arid rangelands. In some places they inhabit low lying areas of dense scrub. Females tend to be more easily alarmed by people than males who sometimes tolerate quite close approach.
Euros have similar diet preferences to Red Kangaroos but eat both young and mature grass in favour of forbs or shrubs. Competition is reduced by segregation of the two species between the hills and plains, respectively. However, in many places this is only marked on the steep slopes and ridges as both species may occupy the footslopes. Male Euros follow creeks and deep drainage channels onto the plains during drought.
Euros have the capacity to recycle urea through their saliva and so have a lower nitrogen requirement than the other kangaroos since some that would be excreted in the urine is conserved. Euros have a lower water turnover than Red Kangaroos and choose humid microhabitats in summer such as rock overhangs, shallow caves and the undercut banks of creeks. This behaviour reduces their water loss for cooling. Euros will enter an unoccupied building or shed if the door is left open in mid-summer, using them as pseudo caves, an action that Red Kangaroos would never take. Euros are also not fully dependent on water bodies to drink as they have the capacity to find subterranean water and dig soaks in creek beds.
Euros are adapted to endure drought but may suffer high mortality under such harsh conditions. Males often range out of the hills to find sufficient food to satisfy their larger bulk than females. Red Kangaroos are more mobile and attempt to avoid the extremes of drought by tracking localised rainfalls to gather green pick.
Euros, like Red Kangaroos, are continuous breeders and the timing of sexual maturity and the progress of offspring development is very similar. However, female Euros tend to shut down reproduction (i.e. enter anoestrus) under less severe drought than Red Kangaroos. As the mother enters drought, her offspring die in order of their energy and nutrient demands. First the young-at-foot dies, then the pouch young as the mother cannot meet its milk requirement and then the embryo in utero is born. If drought persists the latter's fate is sealed but rainfall and a flush of green vegetation may see it through. If the female loses all her offspring and drought persists then she ceases to come into oestrus.
When female Euros are fat and in good condition they tend to produce a preponderance of sons. At other times the offspring sex ratio is equal or even biased towards daughters. Sons grow more rapidly than daughters once they leave the pouch and so are a greater demand on the mother. However, by investing in her sons when she has energy reserves to spare she may give them a boost in the growth stakes so that they have good survival in their early years and grow large enough to become alpha males. This investment is short-term for the mother since her sons disperse a few months after weaning. In contrast her daughters are 'cheap' to produce but stay in or around their mother's home range and so she has to share some of her resources with them in the long-term. This balances the costs so that even though the ratio of sons to daughters may be biased under some conditions or periods of a female's life, the ratio in the population as a whole is equal.
Male Euros epitomise the extreme dimorphism in the kangaroos as you may see a heavily muscled 50 kg male mating with a diminutive and gracile 15 kg female. Like Red Kangaroos, male Euros compete amongst themselves for consortship with a female who may lead half a dozen or more potential suitors on a chase through the hills. Euro society is somewhat more compact in the hills and individuals more sedentary than the roaming Reds on the broad sweep of the plains. Thus competition amongst male seems more intense and 'mating groups' typically include more males than in Red Kangaroos. The exertion of competing and keeping up with a flighty female takes its toll and large males often temporarily retire to better pasture to re-build condition. Thus one male does not have exclusive dominion but a few large males will mate with most of the oestrous females.
F You should watch out for aggregations of males around a female, as this is a fascinating chance to see lots of interesting interactions.
Euros are typically more sedentary and more solitary than Red Kangaroos. You should expect to see a mother and her offspring foraging at some distance from others. Males move amongst the females checking their reproductive status but only dwell if she is nearing oestrus.
Young males sometimes gather in pairs or trios to box. Males start this behaviour with their mother as sparring partner and it persists through life with a peak in the juvenile and early adulthood period. The combatants meet in vigorous and extended bouts but the goal is practice of techniques and wrestling down an opponent rather than exacting a final and damaging defeat. In other words, it is play-fighting where opponents invite a bout by facing off and vigorously scratching their sides, eventual losers kick more than winners and defeat comes from a strong backwards and downwards push, if at all. In contrast, when the fight is for consortship the battle is typically swift and the winner delivers hard kicks to its opponent's abdomen while raking its face and biting its ears in a clinch. You can tell something about a male Euro's battles by the nicks out of his ears. The abdomen may be scarred but as in all the kangaroos, the skin is thickened in males to provide some protection against others' kicks.
Croft DB (1981) Social behaviour of the euro, Macropus robustus (Gould), in the Australian arid zone. Australian Wildlife Research 8, 13-49.
Dawson, TJ (1995) Kangaroos: biology of the largest marsupials. (UNSW Press: Sydney)