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Macropus robustushill wallaroo

By Kyle Davis

Geographic Range

Hill wallaroos are found only in western Australia in New South Wales, the Pilbara district, and Queensland. An uncommon subspecies, Macropus robustus isabellinus is limited in distribution to Barrow Island, off of Pilbara. (Arnold, et al., 1993; Ealey, 1967; Ellis, et al., 2008)

Habitat

Hill wallaroos are usually found on or in rocky hills, caves, and rock formations with large overhangs, anything that can provide shelter from the intense heat during the day. They are also commonly found in shrublands and along streams, near their main food and water sources. A study by Taylor (1983) found that, when hill wallaroos seek shelter, larger adult males occupied much rockier areas than smaller males or females. (Ellis, et al., 2008; Taylor, 1983)

  • Range elevation
    0 to 500 m
    0.00 to 1640.42 ft
  • Average elevation
    330 m
    1082.68 ft

Physical Description

Hill wallaroos are bipedal marsupials with coat color varying from light gray to black. Hill wallaroo lengths can reach 100 to 140 cm. Males weigh from 28 to 42 kg and are much larger than females at 18 to 24 kg. Compared to other wallaroos, hill wallaroos have shorter and wider torsos and shorter limbs, both presumed adaptations for their rocky terrain. They also have short but wide hind feet with powerful legs used to jump up to 4 m. The feet have roughened soles on the bottom for extra grip. (Dawson, 1995; Nowak and Wilson, 1991)

  • Sexual Dimorphism
  • male larger
  • Range mass
    18 to 42 kg
    39.65 to 92.51 lb
  • Range length
    100 to 140 cm
    39.37 to 55.12 in
  • Average basal metabolic rate
    33.056 W
    AnAge

Reproduction

Hill wallaroos breed year-round and are monogamous. To attract a mate, males display their dominance to other males through frequent fighting and displaying themselves for females to see. The major way to display dominance or defending females is by initiating "boxing matches" where two males fight until one surrenders. These matches are rarely fatal. (Arnold, et al., 1993; Croft, 1982; Rose, et al., 1997)

Year-round breeding is common and the number of offspring is one per year. Breeding interval is influenced by the number of pouch young a female has, as a joey grows the female can't accommodate two joeys and must wait until one has left the pouch before another can be raised. The average gestation period is 36 days (range 30 to 38). The average time of weaning occurs around 15 to 16 months. Females wait until weaning has stopped in order to mate again. The average age of sexual maturity is 18 to 19 months for males and 22 months (range 21 to 24) for females. When a hill wallaroo is born, the average weight is only 0.703 g. The young, or joey, stays in the mother's pouch after birth for protection. The joey is in the mother's pouch full-time until month 6, when it may tumble out of the pouch, but quickly climbs back in. Soon after, the joey becomes active and grows rapidly. By about the 37th week (231 to 270 days) of the joey's life, the mother doesn't allow the joey back into her pouch and the joey is considered independent. (Clancy and Croft, 1992; Hirst, 2005; Inns, 1982; Poole and Merchant, 1987a; Russel and Richardson, 1971)

  • Breeding interval
    Hill wallaroos are able to breed once yearly.
  • Breeding season
    Hill wallaroos breed all year round.
  • Range number of offspring
    1 (high)
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    30 to 38 days
  • Average gestation period
    36 days
  • Range weaning age
    15 to 16 months
  • Average weaning age
    17 months
  • Range time to independence
    231 to 270 days
  • Average time to independence
    255 days
  • Range age at sexual or reproductive maturity (female)
    21 to 24 months
  • Average age at sexual or reproductive maturity (female)
    22 months
  • Range age at sexual or reproductive maturity (male)
    18 to 19 months
  • Average age at sexual or reproductive maturity (male)
    18 months

Care for the young of Macropus robustus is mostly handled by females. As marsupials, young wallaroos spend most of their time in their mother's pouch, typically for about 9 months. After this, the young continues to have a close relationship with the mother, including resting together and grooming each other. The father provides protection against predators for the entire weaning period. After about 20 months, the young are fully independent, no longer relying on a parent for food acquisition. At this age, their relationship with the father usually weakens but their relationship with their mother stays strong. (Hirst, 2005; Russel and Richardson, 1971)

  • Parental Investment
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
    • protecting
      • male
  • post-independence association with parents

Lifespan/Longevity

The longest known lifespan of a hill wallaroo in the wild is 24 years and the longest known lifespan in captivity is 22 years. What limits lifespan is the degradation of the immune system and organ function through aging. ("AnAge entry for Macropus robustus", 2012; Clancy and Croft, 1990; Poole and Merchant, 1987b)

  • Range lifespan
    Status: wild
    24 (high) years
  • Range lifespan
    Status: captivity
    22 (high) years
  • Typical lifespan
    Status: wild
    20 to 24 years
  • Typical lifespan
    Status: captivity
    18 to 22 years

Behavior

Hill wallaroos move around by hopping on their massive hind legs. Hill wallaroos generally locomote to new feeding areas within their home range. Males sometimes interact through fighting, or "boxing" with each other. Males mostly use their powerful feet to kick-box until one contestant forfeits. Males display dominance in this way in order to maintain the social hierarchy or obtain access to females for mating. Hill wallaroos interact with each other through grooming. Grooming occurs between every individual but is more frequent between young and their mothers. Males rarely groom each other. (Arnold, et al., 1993; Croft, 1982)

  • Range territory size
    40 to 76 km^2
  • Average territory size
    65 km^2

Home Range

The home range of hill wallaroos depends on suitable vegetation availability. Most hill wallaroos find a large patch of vegetation and stay there, the size is typically 40 to 76 square kilometers. They have been known to travel up to 18 km outside of their home range in search of other foraging opportunities. (Arnold, et al., 1993; Croft, 1982)

Communication and Perception

The most frequent visual and tactile forms of communication observed between hill wallaroos is fighting. Most fights take the form of boxing and involve two sexually-mature males competing for females and displaying dominance. To engage in a fight, males give a head-bobbing motion where they arch their heads back and flick their neck into an erect posture. Males do this head-bobbing motion multiple times until it attracts another male's attention. The other male will then either fight or display submission. Male hill wallaroos interact with a potential mate by sniffing her and displaying himself to her. This display includes a side-to-side sweeping motion, indicating to the female that he is ready to mate. As an alarm to surrounding hill wallaroos, they release a sound similar to a hiss, exhaled through the nose. Then they pounds their foot on the ground and run away. (Croft, 1982)

Food Habits

Herbivorous hill wallaroos mostly graze on soft-textured grasses and shrubs. All foraging occurs mainly within the home range. In the Pilbara district in northwest Australia, there is low rainfall, meaning poor soils and less vegetation. However, a large number of sheep (Ovis aries) pastures in this region increase the success of hill wallaroos. Additionally, their ability to conserve water makes it possible for them to persist in harsh conditions. These animals can live up to two weeks without drinking water, instead they survive on water metabolized from the plants that they eat. (Ealey, 1967; Ealey, et al., 1965; Free, et al., 1970)

  • Plant Foods
  • leaves

Predation

Hill wallaroos are preyed on by red foxes (Vulpes vulpes), which prey on young wallaroos while they are defenseless and out of the mother's pouch. They are also preyed on by humans (Homo sapiens), which take them for pelts and meat. This hunting has been restricted by the Environmental Protection and Biodiversity Conservation Act of 1999. Hill wallaroos avoid predators through their social habits and alarm signals. Alarm signals are powerful and loud foot stomps, followed by high-pitched hisses to warn others of danger and run away. (Banks, et al., 2000; Croft, 1982)

Ecosystem Roles

Hill wallaroos may help to disperse seeds through their grazing. They are hosts to damaging protozoan parasites, Toxoplasma gondii, which cause toxoplasmosis. Advanced stages of toxoplasmosis cause flu-like symptoms and eventually brain damage. This is a serious problem for marsupials and can cause death. According to a study by Camps et al. (2008), there have been serious outbreaks of toxoplasmosis in most zoos in the midwestern United States. This disease mostly affects felids, but can spread to any mammal and is dangerous because the disease can spread to people. Hill wallaroos are also impacted by cutaneous Leishmaniasis. This parasite causes skin lesions and breakdown of epidermal tissue in affected areas. Another protozoan parasite of the wallaroo is Trichomonas vaginalis. This parasite causes trichomoniasis. This affects the urethra of the wallaroo and can cause inflammation and irritation. (Camps, et al., 2008; Dougall, et al., 2009; Dubey and Crutchley, 2008; Taylor, 1983)

Commensal/Parasitic Species
  • Toxosplasma gondii
  • Leishmaniasis
  • Trichomonas vaginalis

Economic Importance for Humans: Positive

Hill wallaroos have historically benefited humans through the hunting and fur trade, which is now illegal due to the Environmental Protection and Biological Conservation Act of 1999. Hill wallaroos are also important models in behavior research and other research. Studies on hill wallaroos have improved our understanding of food preferences, lifespan, and reproductive phases. (Banks, et al., 2000; Camps, et al., 2008; Croft, 1982)

  • Positive Impacts
  • food
  • body parts are source of valuable material
  • research and education

Economic Importance for Humans: Negative

There are no known adverse effects of Macropus robustus on humans.

Conservation Status

Hill wallaroos are listed as "least concern" by the IUCN due to their wide distribution in Australia and the fact that significant populations occur in protected areas. Although there are no major threats, the Burrow Island subspecies of hill wallaroos are in poor health as a direct result of poor nutrition. This subspecies consists of about 18,000 individuals. (Bradshaw and King, 2008; Ellis, et al., 2008)

Contributors

Kyle Davis (author), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

biodegradation

helps break down and decompose dead plants and/or animals

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

2012. "AnAge entry for Macropus robustus" (On-line). Accessed November 16, 2013 at http://genomics.senescence.info/species/entry.php?species=Macropus_robustus.

Arnold, G., D. Steven, J. Weeldenburg. 1993. Influences of remnant size, spacing pattern and connectivity on population boundaries and demography in euros Macropus robustus living in a fragmented landscape. Biological Conservation, 64/3: 219-230.

Banks, P., A. Newsome, C. Dickman. 2000. Predation by red foxes limits recruitment in populations of eastern grey kangaroos. Austral Ecology, 25/3: 283-291.

Bradshaw, S., J. King. 2008. Comparative water metabolism of Barrow Island macropodid marsupials: Hormonal versus behavioural-dependent mechanisms of body water conservation. General and Comparative Endocrinology, 155/2: 378-385.

Camps, S., J. Dubey, W. Saville. 2008. Seroepidemiology of Toxoplasma gondii in zoo animals in selected zoos in the Midwestern United States. The Journal of Parasitology, 94/3: 648-653.

Clancy, T., D. Croft. 1990. Home range of the common wallaroo, Macropus robustus erubescens, in far western New South Wales. Australian Wildlife Research, 17/6: 659-673.

Clancy, T., D. Croft. 1992. Population dynamics of the common wallaroo (Macropus robustus erubescens) in arid New South Wales. Wildlife Research, 19/1: 1-15.

Croft, D. 1982. Observations on the behaviour of the Antilopine wallaroo. Australian Mammalogy, 5/1: 9-20.

Croft, D. 1981. Social behaviour of the euro, Macropus roubustus, in the Australian arid zone. Australian Wildlife Research, 8: 13-49.

Dawson, T. 1995. Kangaroos: Biology of the Largest Marsupials. Sydney, Australia: UNSW Press.

Dougall, A., C. Shilton, J. Low Choy, B. Alexander, S. Walton. 2009. Short report: New reports of Australian cutaneous leishmaniasis in northern Australian macropods. Epidemiology and Infection, 137/10: 1516-1520.

Dubey, J., C. Crutchley. 2008. Toxoplasmosis in wallabies (Macropus rufogriseus and Macropus eugenii): blindness, treatment with atovaquone, and isolation of Toxoplasma gondii. The Journal of Parasitology, 94/4: 929-923.

Ealey, E. 1967. Ecology of the euro, Macropus robustus, in north-western Australia. CSIRO Wildlife Research, 12: 27-51.

Ealey, E., P. Bentley, A. Main. 1965. Studies on water metabolism of the hill kangaroo, Macropus robustus (Gould), in northwest Australia. Ecology, 46/4: 473-479.

Ellis, M., P. Menkhorst, J. van Weenen, A. Burbidge, P. Copley, M. Denny, J. Woinarski, P. Mawson, K. Morris. 2008. "IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2." (On-line). Macropus robustus. Accessed September 08, 2013 at http://www.iucnredlist.org/details/40565/0.

Free, J., R. Hansen, P. Sims. 1970. Estimating dryweights of foodplants in feces of herbivores. Journal of Range Management, 23/4: 300-302.

Hirst, S. 2005. The Antilopine wallaroo: An unusual 'roo. Australian Wildlife Research Comittee, 3/5: 1-10.

Inns, R. 1982. Seasonal changes in the accessory reproductive system and plasma testosterone levels of the male tammar wallaby, Macropus eugenii, in the wild. Reproduction, 66/1: 675-680.

Macdonald, D. 2006. The Encyclopedia of Mammals. Oxford: Oxford University Press.

Morris, K. 1996. Action Plan for Australian Marsupials and Monotremes. Canberra: Wildlife Australia.

Nowak, R., D. Wilson. 1991. Walker's Mammals of the World. Baltimore and London: The Johns Hopkins University Press.

Poole, W., J. Merchant. 1987. Reproduction in captive wallaroos-the eastern wallaroo, Macropus robustus, the euro, Macropus erubescenes and the antilopine wallaroo, Macropus antilopinus. Australian Wildlife Research, 14/3: 225-242.

Poole, W., J. Merchant. 1987. Reproduction in captive wallaroos: the eastern wallaroo, Macropus robustus, the euro, M.R. erubescens and the antilopine wallaroo, M. antilopinus. Australian Wildlife Research, 14: 225-242.

Rose, R., C. Nevison, A. Dixson. 1997. Testes weight, body weight and mating systems in marsupials and monotremes. Journal of Zoology, 243/3: 523-531.

Russel, E., B. Richardson. 1971. Some observations on the breeding, age structure, dispersion and habitat of populations of Macropus robustus and Macropus antilopinus (Marsupialia). Journal of Zoology, 165/1: 131-142.

Sadleir, R. 1965. Reproduction in two species of kangaroo (Macropus robustus and Megaleia rufa) in the arid Pilbara region of southwest of Australia. Journal of Zoology, 145/2: 239-261.

Taylor, R. 1983. Association of social classes of the wallaroo, Macropus robustus. Australian Wildlife Research, 10/1: 39-45.

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