(Macropus robustus).

The Common Wallaroo is also known by the names: Euro, Eastern Grey Wallaroo, Red Wallaroo, Roan Wallaroo, Barrow Island Wallaroo, Hill Kangaroo and Biggada. They can be identified by their dark grey colour which is reddish above and paler under the body. Their fur is shaggy and coarse and can varying from long to short among the subspecies. In common with a number of other species of wallaroo, the Common Wallaroo has a large, bare, black rhinarium. It also shares with other wallaroos a distinctive stance; shoulders thrown back, elbows tucked into the sides and wrists raised. When disturbed, it utters a loud hiss, associated with exhalation. It also has a characteristic 'cch-cch' vocalisation.

Measured from nose to tail tip with animal extended so that dorsal suface approximates a straight line, males can attain a length of almost 2 metres while females reach a length of 1.5 metres. Their tails make up half of this length. Males can weigh up to 46.5 kg while females reach 25 kg.

A number of sub-species exist. Macropus robustus robustus is found in the eastern, non-arid, temperate areas up to the tropical mainland. Macropus robustus erubescens is found over the remainder of the mainland except in the extreme northem and southem parts. Macropus robustus woodwardi is found in the Kimberley region of Western Australia and the north-westem Northern Territory. Macropus robustus isabellinus is found on Barrow Island in Western Australia.

The Common Wallaroo's habitat is varied but usually features steep escarpments, rocky hills or stony rises; places where caves, overhanging rocks and ledges provide shelter and relief from extreme heat in areas experiencing prolonged periods of high temperature. It leaves this shelter in the cool of the evening to graze, primarily upon grasses and shrubs, usually within a limited home range which may include lower slopes and surrounding plains. Well adapted to aridity, it can maintain itself and even breed successfully on pastures of low protein content and it can survive without frequent access to free water if it has access to refuges from solar radiation and to food plants of sufficient water content.

There are marked differences between males and females. Mature males attain nearly double the weight of mature females and are usually darker in colour. The two best known subspecies also differ so markedly that they have distinct common names. Macropus robustus robustus, which inhabits the eastern and western slopes of the Great Dividing Range, has shaggy, dark grey fur and is known as the Wallaroo or Eastern Wallaroo. The reddish and shorter-haired Macropus robustus erubescens, which occupies most of the continent westward of this region, is known as the Euro. Two smaller subspecies have more limited distributions.

Sexual maturity is attained at 18-24 months. Breeding may occur throughout the year but reproduction is reduced in times of drought and may cease if drought is prolonged. In processes known as post-partum oestrus and embryonic diapause, the female is able to suspend the development of an embryo until either better climatic conditions return or until an earlier joey has left the pouch. Females of the Eastern Wallaroo and Euro differ somewhat in their reproductive patterns. The oestrous cycle of the former is about 33 days while that of the Euro is about 45 days. In the Eastern Wallaroo, the length of gestation is about 32 days and pouch life about 260 days, the respective periods are about 34 and 238 days in the Euro.

The Common Wallaroo is essentially solitary. The density of populations is governed both by the amount of available shelter and by proximity to food and water. Seasonal conditions, competition from other grazing animals, and human predation may reduce populations to less than the apparent carrying capacity of an area. Densities as high as 13 per square kilometre have been recorded and, following a population crash, as low as 0.04 per square kilometre.

A wash drawing of a skull among the papers of sir Joseph Banks demonstrates that a Common Wallaroo was one of the three macropods collected in 1770 near the Endeavour River, Queensland, by Cook's expedition. The species was subsequently described by Gould from two animals collected in 1839 in the Liverpool Range, NSW.

Although the Common Wallaroo is abundant, it remains a protected species. Permits may be granted by State wildlife authorities to reduce numbers in prescribed areas.

Source: 'Complete Book of Australian Mammals' - Australian Museum, 1983.

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