Common or hill wallaroo (Macropus robustus)
The common wallaroo or hill kangaroo is one of the largest and heaviest kangaroos. The body mass varies from 6.75-35.75 kg. The head to tail length is 1138-1986 mm for males and 1107-1508 mm for females. The tail is about 551-901 mm for males and 534-749 mm for females.
This stocky kangaroo has coarse, shaggy fur, a hairless muzzle, relatively short, thick tail and an upright hopping style (2-5). The robust body shape, with shorter limbs than other kangaroos, may be an adaptation for leaping around on rocks; the short, broad hind feet have roughened soles to give extra grip (4). The mature male is up to twice as heavy as the female and has particularly thick-set shoulders and forearms (4,6). Coat colour varies from reddish-brown to very dark blue-grey, almost black, and is generally lighter on the underparts, being pale to nearly white (4). The medium length pelage is directed downwards. The fur is less dense than that of red and grey kangaroos and includes thin and sparse underfur. The muzzle has a bare black rhinarium and a slight lateral inflation. The nasal region and the back of the ears are black, while the lips, the inside and base of the ears are white or pale. The legs and tail have a very dark brown color that bleeds into a black tint near the tips of both extremeties.
The teeth have vertically placed roots in the second and third incisors. The second incisor has enamel covering about the height and length of the crown. The outer face of the tooth has an indistinct groove. The third incisor is long, equalling the combined length of the first and second incisors and has an external notch near the front edge. The third premolar is about 7 mm long and the fourth premolar is large and powerful. The molars have well developed transverse ledges with connecting ridges that are small and sometimes absent. The stance is distinctive: the shoulders are thrown back, elbows tucked into the sides and wrists raised. Strahan 1995; Tyndale-Biscoe 1973; Nowak 1991
occurs across northwestern Australia (4).
The species is generally found in varied habitats in many regions of Australia, such as desert or dune and scrub forest. It prefers habitats with steep escarpments, rocky hills, overhangs, and caves that provide shelter and shade during periods of high temperature (Clancy and Croft 2008). It also shelters in dense shrub around streams. It can survive where the temperatures rises to 120 F and where the average rainfall is below 380 mm/year. Strahan, 1995; Tyndale-Biscoe, 1973; Nowak, 1991. It grazes on grasses and shrubs and can inhabit regions of sparse vegetation.
Often referred to as a 'hill kangaroo', the common wallaroo typically inhabits mountainous areas, rocky hills and steep escarpments, although it may also use stony rises, grasslands and plains (2) (4) (7) (8). Caves, overhanging rocks and ledges are often used for shelter, particularly from extreme heat, and as refuges from predation (1) (2) (4) (8). The species may also shelter in dense shrub around streams (1).
Wallaroos are herbivores that do not need much water or highly nutritious foods. They drink less often than most species in the family and eat foods that have lower nutritional value. They mainly feed on spinifex, soft grasses, shrubs, herbs and low protein/ low fiber grasses. In the spring they graze on grass inflourescences and forbs. Strahan, 1995; Tyndale-Biscoe, 1973.
Plant Foods: leaves
The average lifespan is 18.5 years in the wild and 19.6 years in captivity. The maximum longevity is 22 years in captivity (Richard Weigl 2005) and perhaps 24 years in the wild (Fisher et al. 2001).
Wallaroos reach sexual maturity before two years of age. They are opportunistic breeders with no regular seasonal pattern of reproduction. Under good breeding conditions, nearly all females have one running offspring and one attached to a teat in the pouch. Under poor breeding conditions, females experience embryonic diapause. The gestation period is about 32-34 days and the pouch life ranges from 237-269 days. Strahan,1995; Tyndale-Biscoe, 1973; Thomas, 1888; Nowak, 1991
Average birth mass: 0.703 g.
Average number of offspring: 1.
Average age at sexual or reproductive maturity of the male is 670 days and for the female
is 547 days.
The Red List Category was assessed as Least Concern (LC) in 2008. This is due to the wallaroo's wide distribution, large population, occurrence in several protected areas, lack of major threats, and as it is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.
The species is widespread and relatively common in appropriate habitats. The population is stable. In Victoria, the wallaroo is rare and in urgent need of protection. Due to its isolation, it is vulnerable to predation and human land development. It is sparse in the wheatbelt of New South Wales. In Queensland, it is common in some agricultural areas with removal of M. giganteus. It is subject to commercial take under nationally approved management plans. Total population size on Barrow Island is estimated at 1,800 individuals. The population trend is Stable
There appear to be no major threats to this species overall. The Barrow Island population has recently been found to suffer from anaemia and poor condition and this may be related to nutritional stress (S. D. Bradshaw pers. comm.).
There are not thought to be any major threats to the common wallaroo (1) (4), and the steep, rocky areas it favours help to protect this species to some degree (4) (10). In addition, like many other large kangaroo species, the common wallaroo may have benefitted from artificial water holes provided for livestock, as well as a reduction in dingo numbers and the presence of sheep, creating favourable grazing conditions (2) (9) (10) (11). Although the common wallaroo is legally culled in some areas for food, skins, and because of alleged damage to pastures and crops (2) (7) (10) (11), it is estimated to make up only about three percent of the overall commercial kangaroo quota (4). However, there is some controversy over how many kangaroos can be safely harvested, particularly in light of increasing human habitat modification and drought (2). The Barrow Island wallaroo, M. r. isabellinus, may be more vulnerable than the mainland subspecies, particularly in light of its smaller, isolated population, estimated to number only around 1,800 individuals (4) (7). This distinctive subspecies is listed as Vulnerable under the Environmental Protection and Biodiversity Conservation Act 1999 (EPBC), with threats including inappropriate fire regimes, introduced species, road fatalities, and habitat degradation associated with the development of oilfields (3) (5). The population has also recently been found to suffer from anaemia and poor condition, possibly related to nutritional stress (1) (7).
Mainland populations are present in a number of protected areas.
The mainland populations of the common wallaroo are widespread and abundant, and are present in a number of protected areas (1). Commercial take is regulated under nationally approved management plans (1) (7), which aim to maintain populations of common wallaroo in an ecologically sustainable manner (10) (12) (13). Barrow Island is also protected as a nature reserve (3) (4). Conservation priorities for the vulnerable Barrow Island wallaroo include determining the extent of nutritional stress in the population, continuing with long-term population monitoring, and determining if oil field management can be modified to improve the condition of the wallaroo population. It will also be important to prevent introductions of non-native species, to monitor and improve traffic management to reduce road fatalities, to develop an appropriate fire management strategy, and to restore land impacted by the oil field (5) (7).
Wallaroos are well adapted to arid environments. Aside from their behavioral adaptations, wallaroos are interesting to scientists because of their physiological adaptations. Wallaroos have a very efficient excretory system that recycles nitrogen and urea to make a very concentrated urine. This physiological adaptation can provide scientists with much information about evolution of physiological characteristics. Tyndale-Biscoe, 1973; Warneke, 1995.
he common wallaroo (Macropus robustus) or wallaroo, also known as euro or hill wallaroo is a species of macropod ( Kangaroo). Particularly one subspecies (M. r. erubescens) is commonly called euro.
- There are four subspecies of the wallaroo:
- Eastern wallaroo (M. r. robustus) – Found in eastern Australia, males of this subspecies have dark fur, almost resembling the black wallaroo (Macropus bernardus). Females are lighter, being almost sandy in colour.
- Euro (M. r. erubescens) –  Found on covering most of its remaining range, this subspecies is variable, but mostly brownish in colour.
- M. r. isabellinus – This subspecies is restricted to Barrow Island in Western Australia, and is comparatively small. It is uniformly reddish brown.
- M. r. woodwardi – This subspecies is found in the Kimberley region of Western Australia and in a band running through Northern Territory. It is the palest subspecies and is a dull brown-grey colour.
The eastern wallaroo (Macropus robustus robustus)—which is grey in colour—occupies the eastern slopes of the Great Dividing Range and the euro (Macropus robustus erubescens)—rufous in colour—occupies land westward.
- ^ a b Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M. eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 65. OCLC 62265494. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3.
- ^ a b c Ellis, M., Menkhorst, P., van Weenen, J., Burbidge, A., Copley, P., Denny, M., Woinarski, J., Mawson, P. & Morris, K. (2008). Macropus robustus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 28 December 2008. Database entry includes justification for why this species is of least concern
- ^ a b WE Poole and JC Merchant (1987): Reproduction in Captive Wallaroos - the Eastern Wallaroo, Macropus-Robustus-Robustus, the Euro, Macropus-Robustus-Erubescens and the Antilopine Wallaroo, Macropus-Antilopinus. Australian Wildlife Research 14(3) 225 - 242. online link
- ^ a b c d e Menkhorst, Peter (2001). A Field Guide to the Mammals of Australia. Oxford University Press. p. 118.
- ^ TF Clancy and DB Croft (1992): Population dynamics of the common wallaroo (Macropus robustus erubescens) in arid New South Wales. Wildlife Research 19(1) 1 - 15. online link
The Barrow Island wallaroo is known only from Barrow Island, off the Pilbara coast of Western Australia.
The wallaroo is often solitary, occupying a relatively small, stable home range near to a rocky outcrop or water and moving out of rough country to graze on grasses and shrubs in adjoining areas (2,4,9). Small groups sometimes form around favoured resources, but are usually loose in size and composition (2,6). The wallaroo can survive harsh conditions by using caves and rocky outcrops for shelter and seems able to go for two to three months without drinking, surviving on the water contained in food plants (2,9).
The wallaroo is believed to be polygynous (6) and is an opportunistic breeder, able to breed throughout the year, but often ceasing reproduction during prolonged droughts (2,8,10). A single, tiny young is born after a gestation period of 30-38 days (8). It climbs, unaided, through the female's fur and into the pouch, where it attaches to a teat and begins to suckle (11). Most development occurs in the pouch; the young emerges after around 231-270 days (8). The young is suckled for at least 12-14 months, with males reaching sexual maturity at around 18-20 months in captivity and females at 14-24 months (8). Individuals may live over 18 years in the wild (2). In a process called embryonic diapause, the female can become pregnant again soon after giving birth. The new embryo stays dormant until the first young is ready to leave the pouch or is lost, when the embryo resumes development and is born when the pouch is vacant. This means the female can quickly replace young lost to predators or drought and can have embryos ready to develop as soon as conditions become favourable (2,11).
The four subspecies are based mainly on colour, size, and genetic differences:
1. Eastern wallaroo (M.r. robustus)
2. Inland wallaroo or 'euro' (M.r. erubescens)
3. Northern wallaroo (M.r. woodwardi)
4. Barrow Island wallaroo (M.r. isabellinus). This small, stocky subspecies reaches only half the size of the other forms (3,4). There are about 1,800 individuals on Barrow Island, off the coast of Western Australia (1,4,7)..
In some areas, M.r. robustus and M.r. erubescens overlap and are thought to hybridise (4).