Eastern grey kangaroo  (Macropus giganteus)

Classified as Least Concern (LC) on the IUCN Red List (1).

One of the largest kangaroo species (3), the eastern grey kangaroo has soft, thick, grey-brown fur, paler on the underparts, with a finely haired muzzle, and dark tips to the paws, feet and tail (2) (3) (4) (5). There may also be a darker line along the back (3). The length and shading of the fur varies with location, with the subspecies Macropus giganteus tasmaniensis having longer, denser and browner fur than its mainland counterpart, M. g. giganteus (3) (4) (6). The male eastern grey kangaroo is larger than the female, with a more heavily muscled head, chest and forelimbs, but is otherwise similar in appearance (3) (4) (5).

The eastern grey kangaroo can be distinguished from the closely related western grey kangaroo, Macropus fuliginosus, by its grey rather than brown colouration. The western grey kangaroo also tends to be darker around the head, and sometimes has a blackish patch around the elbow (3) (4).

The eastern grey kangaroo has a wide distribution across eastern mainland Australia, from northeast Queensland to southeast South Australia and southern Victoria (1) (2) (3) (4) (7). Subspecies M. g. tasmaniensis occurs in eastern Tasmania, and has also been introduced to Maria Island and Three Hummock Island (1) (6) (8).

The eastern grey kangaroo is found in areas of higher rainfall, including woodland, dry sclerophyll forest, mallee scrub, shrubland and heathland (1) (3) (4) (5) (8). It requires trees or scrub for cover and open areas for feeding (2) (4), and can also occur in agricultural land, introduced grassland and other modified landscapes (1).

The eastern grey kangaroo is mainly active at night, resting in shelter during the heat of the day (1) (2) (4) (5). Like other kangaroos, it is able to travel at great speed, using the powerful, enlarged hindquarters for leaping, aided by the long tail, which acts as a balance and rudder (2). Perhaps surprisingly, kangaroos are also good swimmers (4) (5). The diet consists of grasses, herbs, leaves and other low, shrubby vegetation (5) (6). When alarmed, this kangaroo makes a guttural cough and may thump the hind feet (5). The eastern grey kangaroo is one of the most social of the large kangaroos, often gathering in groups, or ‘mobs’, of ten or more animals, comprising mainly females and young. Larger, loose aggregations may form where food is abundant (1) (2) (3) (5) (6). Adult males usually join the groups when the females are ready to mate, and engage in ritualised fights with rival males (2) (5) (9).

Although breeding may occur year-round, the eastern grey kangaroo usually gives birth in summer, between September and March (2) (3) (5) (7) (10). Like other kangaroos, the young is born at an early stage of development, after a gestation period of just 36 days (2) (11). Tiny, naked and blind, the newborn climbs through the female’s fur and into the forward-facing pouch, where it attaches to a teat to undergo the rest of its development (3) (9). The young eastern grey kangaroo develops more slowly than many other kangaroos, first emerging from the pouch after around 283 days, at a time when food is most available, and finally leaving it completely after around 320 days (2) (3) (7) (11). Usually a single young is born, weighing just over 0.8 grams at birth, although twins are sometimes recorded (2) (3) (5). The young is weaned by about 18 months (2) (11). Females reach sexual maturity at around 20 to 22 months and males at 43 months (2) (5), and lifespan may be up to 25 years in captivity (3) (5).

Many kangaroos are able to conceive again soon after giving birth, the new embryo remaining dormant until the first young is ready to leave the pouch or is lost, a process known as embryonic diapause (2) (9). However, this appears to be rare in the eastern grey kangaroo, although it sometimes occurs if conditions are good. The female eastern grey kangaroo may become receptive from 150 days after giving birth, but conception does not usually occur until there is time before the birth for the first young to leave the pouch. The interval between successive births is therefore approximately one year, and dormant embryos are only occasionally found (2) (3) (7) (12).

There are not believed to be any major threats to the eastern grey kangaroo (1), and the species has often benefitted from human activity, expanding its range where artificial watering holes have been provided for livestock. In many areas, the species is regarded as a pest, and is shot under licence and also hunted commercially for its meat and leather (1) (2) (3) (4) (13). However, in some areas the eastern grey kangaroo population is more limited, particularly in densely settled locations (2) (4), and there is some debate over whether kangaroo populations can sustain present hunting levels (2).

There is more concern over the subspecies M. g. tasmaniensis, which has lost over 90 percent of its range due to uncontrolled hunting and habitat loss through agricultural clearing (1) (2) (6) (8) (14). The remaining population is relatively small and fragmented (4) (8) (14), but is now thought to have stabilised (6). However, it is culled under permit due to ongoing conflict with agriculture (6) (8), and is still under threat from land clearance and poaching (8) (14).

The eastern grey kangaroo is present in many protected areas, and is still widespread and abundant (1). The species is protected by law throughout its range (1), and hunting and commercial harvesting are controlled under a range of management plans, which aim to maintain kangaroo populations and manage them as a renewable resource, while attempting to address the conflicts with agriculture (13) (15). Much controversy and debate has surrounded the commercial hunting of kangaroos, but many consider their sustainable use to be a valuable conservation tool (13).

The Tasmanian subspecies, M. g. tasmaniensis, is subject to a number of management measures, and occurs in a number of protected areas in Tasmania. Further conservation actions recommended for this subspecies include continuing to monitor its population levels, continuing to regulate culling, managing habitat within reserves, and using translocation to maintain populations throughout its fragmented and reduced range (6) (8) (14).

To find out more about the conservation of this and other kangaroo species see:

• Dawson, T.J. (1995) Kangaroos: Biology of the Largest Marsupials. UNSW Press, Sydney.
• Maxwell, S., Burbidge, A.A. and Morris, K.D. (1996) The 1996 Action Plan for Australian Marsupials and Monotremes. Wildlife Australia, Canberra. Available at:
  http://www.environment.gov.au/biodiversity/threatened/publications/action/marsupials/index.html

For more information on conservation in Australia see:

• Australian Government - Department of the Environment, Water, Heritage and the Arts:
  http://www.environment.gov.au/index.html
• Australian Wildlife Conservancy:
  http://www.australianwildlife.org/

For more general information on the eastern grey kangaroo see:

• BBC Wildlife Finder:
  http://www.bbc.co.uk/nature/species/Eastern_Grey_Kangaroo

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

• Embryonic diapause: also known as delayed implantation. A reproductive strategy found in some mammals, such as some marsupial, rodent, bear and mustelid species, in which the embryo does not immediately implant in the uterus, but remains dormant, only implanting and continuing development when conditions are favourable. This strategy allows the female to give birth when survival of the offspring is more likely, such as when environmental conditions are more favourable or the previous offspring has been weaned.
• Gestation: the state of being pregnant; the period from conception to birth.
• Mallee: a growth habit of many eucalypt species, in which multiple stems grow from an underground woody root or tuber; also refers to a habitat dominated by eucalypts of this growth type, typical of many semi-arid areas of Australia, and to a number of eucalypt species themselves.
• Sclerophyll: a type of vegetation with hard, thick-skinned leaves; for example, eucalypts and acacias.
• Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
• Translocation: when individual living organisms from one area are transferred and released or planted in another area.

1. IUCN Red List (September, 2009)
   http://www.iucnredlist.org
2. Nowak, R.M. (1991) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore and London.
3. Poole, W.E. (1982) Macropus giganteus. Mammalian Species, 187: 1 - 8. Available at: http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-187-01-0001.pdf
4. Dawson, T.J. (1995) Kangaroos: Biology of the Largest Marsupials. UNSW Press, Sydney.
5. Cronin, L. (2008) Cronin’s Key Guide Australian Mammals. Allen & Unwin, Sydney.
6. Australian Government: Department of the Environment, Water, Heritage and the Arts - Forester Kangaroo (Macropus giganteus tasmaniensis): Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the List of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) (September, 2009)
   http://www.environment.gov.au/biodiversity/threatened/species/forester-kangaroo.html
7. Tyndale-Biscoe, H. (2005) Life of Marsupials. CSIRO Publishing, Collingwood, Victoria.
8. Maxwell, S., Burbidge, A.A. and Morris, K.D. (1996) The 1996 Action Plan for Australian Marsupials and Monotremes. Wildlife Australia, Canberra. Available at: http://www.environment.gov.au/biodiversity/threatened/publications/action/marsupials/index.html
9. Macdonald, D.W. (2006) The Encyclopedia of Mammals. Oxford University Press, Oxford.
10. Pearse, R.J. (1981) Notes on breeding, growth and longevity of the forester or eastern grey kangaroo, Macropus giganteus Shaw, in Tasmania. Australian Wildlife Research, 8(2): 229 - 235.
11. Poole, W.E. (1975) Reproduction in the two species of grey kangaroos, Macropus giganteus Shaw and M. fuliginosus (Desmarest) II. Gestation, parturition and pouch life. Australian Journal of Zoology, 23: 333 - 353.
12. Poole, W.E. and Catling, P.C. (1974) Reproduction in the two species of grey kangaroos, Macropus giganteus Shaw and M. fuliginosus (Desmarest) I. Sexual maturity and oestrus. Australian Journal of Zoology, 22: 277 - 302.
13. Pople, T. and Grigg, G. (1998) Commercial Harvesting of Kangaroos in Australia. Environment Australia, Canberra. Available at: http://www.environment.gov.au/biodiversity/trade-use/wild-harvest/kangaroo/harvesting/roobg-01.html
14. Tanner, Z. and Hocking, G.J. (2001) Status and Management of the Forester Kangaroo in Tasmania, 2000. Nature Conservation Report 2001/02. Department of Primary Industries, Water and the Environment, Hobart. Available at: http://www.dpiw.tas.gov.au/inter.nsf/Attachments/BHAN-54X2J5/$FILE/forester_kang.pdf
15. Department of Environment and Conservation. (2006) Draft New South Wales Kangaroo Management Plan 2007 - 2011. Department of Environment and Conservation, Sydney. Available at: http://www.nswfarmers.org.au/__data/assets/pdf_file/0009/2160/SUB_Draft_Kangaroo_Management_Plan_2007-2011.pdf