Overview

Distribution

Range Description

This species is endemic to eastern mainland Australia and the island of Tasmania (introduced to Maria Island). On the mainland it ranges extensively from north-eastern Queensland (Cape York Peninsula) to south-eastern South Australia (including Fraser Island). It ranges in elevation from sea level to subalpine areas. The subspecies Macropus giganteus tasmaniensis is restricted to Eastern Tasmania (Barker and Caughley 1990).
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Geographic Range

Eastern grey kangaroos can be found on the eastern coastlines of Australia, all of Queensland with the exception of western Cape York, South Wales, and parts of Tasmania, most notably the north eastern portion.

Biogeographic Regions: australian (Native )

Other Geographic Terms: island endemic

  • Strahan, R. 1995. Mammals of Australia. New York: Smithsonian Institution press.
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Physical Description

Morphology

Physical Description

Eastern grey kangaroos are often confused with the western grey kangaroos, which were initially considered a subspecies of the eastern grey. While a stark contrast in fur color can be seen in the throat and other areas of the western grey, eastern grey kangaroos have a more even distribution in fur color. The faces of the two species differ in that the western grey has a darker complexion as opposed to the almost white face of the eastern grey. Eastern greys also lacks the white patch on the upper thigh which is characteristic of a western grey. There is great sexual dimorphism in size, with the males ranging from twice to three times the mass of an average female. Eastern grey kangaroos on the coastline will usually exhibit lighter colored fur than those inland, which are considerably darker in color. Eastern greys in Tasmania and the southern portions of Queensland also exhibit longer fur than in other areas. One other identifying characteristic is the black tip on the tails of this species. Females usually weigh up to about 40 kg, while males can weigh over twice as much, up to 90 kg. The standard metabolic rates of both eastern grey kangaroos and western grey kangaroos are lower than eutherians, although eastern grey kangaroos have a lower standard metabolic rate than western grey kangaroos.

Range mass: 3.5 to 90 kg.

Range length: 1.5 to 1.8 m.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

  • Dawson, T., C. Blaney, A. Munn, A. Krockenberger, S. Maloney. 2000. Thermoregulation by kangaroos from mesic and arid habitats: Influence of temperature on routes of heat loss in eastern grey kangaroos (Macropus giganteus) and red kangaroos (Macropus rufus). PHYSIOLOGICAL AND BIOCHEMICAL ZOOLOGY, 73 (3): 374-381.
  • McCarron, H., R. Buffenstein, F. Fanning, T. Dawson. 2001. Free-ranging heart rate, body temperature and energy metabolism in eastern grey kangaroos (Macropus giganteus) and red kangaroos (Macropus rufus) in the arid regions of South East Australia. Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology, 171(5): 401-411.
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This species is found in sclerophyll forest, woodlands (including mallee scrub), shrubland and heathland (Coulson 2008); also occurs in agricultural lands, introduced grasslands and other modified landscapes. It is nocturnal, gregarious, and large mobs gather where food is abundant.

Systems
  • Terrestrial
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Eastern grey kangaroos inhabit a wide variety of habitats ranging from open woodlands to grasslands. They can also be found in mountains with extensive forest cover. The habitats of this species are usually areas of high rainfall, but this can also range to semi-arid areas.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest ; mountains

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Trophic Strategy

Food Habits

Eastern grey kangaroos are grazers and eat a wide variety of foliage ranging from grasses to forbs (broad-leaved herbs besides grass that grow on plains and meadows). The main choice of food, however, is grass, which grows on the plains that these kangaroos usually inhabit. In captivity, eastern greys may also feed upon fruits, although this is not part of the usual diet in the wild.

Plant Foods: leaves; seeds, grains, and nuts; fruit

Primary Diet: herbivore (Folivore )

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Associations

Ecosystem Roles

Eastern grey kangaroos have a similar impact on the ecoystem as most other species of kangaroo. They are grazers and control the growth and spread of grass and other types of foliage. As with other grazers, this leads to soil dessication if unchecked, but their numbers are not great enough to be considered a serious ecological hazard.

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Predation

Eastern grey kangaroos have few natural predators. They have been hunted for thousands of years by Australian aborigines for fur and meat and later by European settlers. However, in the wild there are no species of animals that truly prey upon this species of kangaroo, with the exception of dingos. The effect of dingos is considered minimal.

Known Predators:

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Life History and Behavior

Behavior

Communication and Perception

Both male and female eastern grey kangaroos usually communicate with each other and their young using clucking noises. When alarmed, they can also emit a guttural cough. This cough is also heard when males warn each other, fight, or display dominance. All grey kangaroos stamp their hind legs on the ground when they sense danger. This stamping, along with the guttural noise, sends a warning that travels quite distantly.

Communication Channels: tactile ; acoustic

Perception Channels: visual ; acoustic

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Life Expectancy

Lifespan/Longevity

Eastern grey kangaroos live for about 7-10 years in the wild, while there are records of those in captivity that have lived in excess of 20 years. Research in southern Queensland has shown that approximately 50% of young joeys fail to live to independence.

Range lifespan

Status: captivity:
25 (high) years.

Average lifespan

Status: wild:
8 years.

Typical lifespan

Status: captivity:
18 to 20 years.

Average lifespan

Status: wild:
20.0 years.

Average lifespan

Status: wild:
19.8 years.

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Lifespan, longevity, and ageing

Maximum longevity: 25 years (captivity) Observations: In one field study, the oldest animals were estimated to be around 20 years old. One specimen obtained as a pouch reportedly lived 25 years in captivity (Poole 1982).
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Reproduction

Male eastern grey kangaroos often 'box' or exhibit other types of aggressive behavior to establish dominance. The dominant male is the most likely individuals to mate with a female in estrus. When a female eastern grey kangaroo reaches estrus, the male will approach and sniff various parts of her body including her pouch and urogenital area. He may also make clucking noises and paw her head and tail, a behavior characteristic of many kangaroo species.

Mating System: polygynous

Eastern grey kangaroos are seasonal breeders (spring and early summer), unlike some kangroo species such as the red kangaroo or even the closely related western grey kangaroo, which breeds continously as long as the conditions are good. The eastern grey kangaroo exhibits embryonic diapause, a condition in which development of the zygote is halted. This is similar to all kangaroo species with the exception of the western grey. The estrous period for eastern grey kangaroos lasts about 46 days, which is longer than the gestation period of 36 days. Sexual maturity for males is reached at about 20 months and for females at 17 months.

Breeding interval: Eastern grey kangaroos breed seasonally

Breeding season: Usually breed in the spring and early summer

Range number of offspring: 1 to 2.

Range gestation period: 34.8 to 38 days.

Average weaning age: 9.5 months.

Average time to independence: 11 months.

Range age at sexual or reproductive maturity (female): 15 to 20 months.

Average age at sexual or reproductive maturity (male): 20 months.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous ; embryonic diapause

Average birth mass: 0.89867 g.

Average number of offspring: 1.

Average age at sexual or reproductive maturity (male)

Sex: male:
1290 days.

A joey, or baby kangaroo, usually stays in the pouch for 11 months during which it feeds from its mother's milk. It feeds for an additional 9 months, on average, from the mother's milk, although it leaves the pouch at 11 months. During this time, the mother provides protection and food and also guidance as the joey comes closer to becoming fully independent. An interesting point about the milk produced by the female kangaroo is that its nutrional content changes depending upon the nutrional requirements of the joey. Thus, the milk produced while the joey is exclusively inside the pouch differs from the milk produced when the joey spends part of its time outside the pouch. Females with joeys that are semi-independent to fully-independent from the pouch usually stay away from large groups, a behavior thought to avoid the risk of predation.

Parental Investment: altricial ; pre-hatching/birth (Protecting: Male); pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female); pre-independence (Provisioning: Female, Protecting: Male, Female)

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Munny, P., Menkhorst, P. & Winter, J.

Reviewer/s
Lamoreux, J. & Hilton-Taylor, C. (Global Mammal Assessment Team)

Contributor/s

Justification
Listed as Least Concern in view of its wide distribution, large population, occurrence in a number of protected areas, lack of major threats, and because it is not in decline.
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There are almost 2 million eastern grey kangaroos in Australia and the surrounding areas, and thus, are not considered to be in any immediate danger of extinction. There was a sharp decline in the popluation of eastern grey kangaroos in the late 1990's especially in Tasmania. However, these kangaroos are now protected by law by the Australian government and most of their range is now on private property. This has enabled the eastern grey kangaroo population to increase and continue growing. There is a large kangaroo industry in Australia but the number of kangaroos killed each year is striclty monitored and regulated by the Australian government.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Population

Population
Mainland populations are abundant (Coulson 2008); these populations have expanded because of increased artificial water points for cattle. The abundance of M. g. tasmaniensis has been estimated between 10,000 and 20,000 animals (Maxwell et al. 1996).

Population Trend
Stable
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Threats

Major Threats
There are no major threats to this species. Animals may be shot under license (in some states a license is not required) where they damage crops, pasture or fences. M. g. tasmaniensis is threatened by loss of habitat through agricultural clearing.
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Management

Conservation Actions

Conservation Actions
The species is present in many protected areas and is protected by national legislation. Regulated harvesting takes place under the supervision of state and federal governments (the latter only manages harvesting when animals are exported).
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

Eastern grey kangaroos do not have much of a negative economic impact on human populations except that they sometimes have a tendency to wander into gardens and grazing lands to feed. This leads to the destruction of private land or property. They are sometimes shot by farmers who want to protect their grazing land, but are not considered a serious economic problem.

Negative Impacts: crop pest

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Economic Importance for Humans: Positive

Eastern grey kangaroos are endemic to the continent of Australia. There is not enough information to suggest that these kangaroos have a positive economic impact on human populations except for the fact that they have been hunted for food by Australian aborignes and Europeans settlers. The kangaroo industry is fairly large in Australia and the number hunted annually is based upon a quota set by the government of Australia.

Positive Impacts: food ; body parts are source of valuable material

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Wikipedia

Eastern grey kangaroo

The eastern grey kangaroo (Macropus giganteus) is a marsupial found in southern and eastern Australia, with a population of several million. It is also known as the great grey kangaroo and the Forester kangaroo. Although a big eastern grey male typically masses around 66 kg (weight 145 lb.) and stands almost 2 m (6.6 ft.) tall, the scientific name, Macropus giganteus (gigantic large-foot), is misleading: the red kangaroo of the semi-arid inland is larger, weighing up to 85 kg.

Description[edit]

Female grazing

The Eastern grey kangaroo is the second largest and heaviest living marsupial and native land mammal in Australia. An adult male will commonly weigh around 50 to 66 kg (110 to 146 lb) whereas females commonly weigh around 17 to 40 kg (37 to 88 lb). Large males of this species are more heavily built and muscled than the lankier Red Kangaroo and can occasionally exceed normal dimensions. One of these, shot in eastern Tasmania weighed 82 kg (181 lb), with a 2.64 m (8.7 ft) total length from nose to tail (possibly along the curves). The largest known specimen, examined by Lydekker, had a weight of 91 kg (201 lb) and measured 2.92 m (9.6 ft) along the curves. When the skin of this specimen was measured it had a "flat" length of 2.49 m (8.2 ft).[3] The eastern grey is easy to recognise: its soft grey coat is distinctive, and it is usually found in moister, more fertile areas than the red. Red kangaroos, though sometimes grey-blue in colour, have a totally different face than grey kangaroos. Red kangaroos have distinctive markings in black and white beside their muzzles and along the sides of their face. Grey kangaroos do not have these markings, and their eyes seem large and wide open. Where their ranges overlap, it is much more difficult to distinguish between eastern grey and western grey kangaroos, which are closely related. They have a very similar body and facial structure, and their noses/muzzles are fully covered with fine hair (though that is not obvious at a distance, their noses do look noticeably different from the noses of reds and wallaroos). The eastern grey's colouration is a light-coloured grey or brownish-grey, with a lighter silver or cream, sometimes nearly white, belly. The western grey is a dark dusty brown colour, with more contrast especially around the head.[4] Indigenous Australian names include iyirrbir (Uw Oykangand and Uw Olkola) and kucha (Pakanh).[citation needed] The highest ever recorded speed of any kangaroo was 64 kilometres per hour (40 mph) set by a large female eastern grey kangaroo.[5]

Ecology[edit]

Eastern greys in native habitat

Although the red is better known, the eastern grey is the kangaroo most often encountered in Australia, due to its adaptability. Few Australians visit the arid interior of the continent, while many live in and around the major cities of the south and east coast, from where it is usually only a short drive to the remaining pockets of near-city bushland where kangaroos can be found without much difficulty. The eastern grey prefers open grassland with areas of bush for daytime shelter and mainly inhabits the wetter parts of Australia.[6] It also inhabits coastal areas, woodlands, sub-tropical forests, mountain forests, and inland scrubs.[6]

Like all kangaroos, it is mainly nocturnal and crepuscular,[4] and is mostly seen early in the morning, or as the light starts to fade in the evening. In the middle of the day, kangaroos rest in the cover of the woodlands and eat there but then come out in the open to feed on the grasslands in large numbers.[4] The eastern grey kangaroo is predominantly a grazer, eating a wide variety of grasses, whereas some other species (e.g. the red kangaroo) include significant amounts of shrubs in the diet.

Behaviour[edit]

Eastern grey kangaroos are gregarious and form open-membership groups.[7] The groups are made up of 2-3 females and their offspring with the same number of males of which one is dominant. They exist in a dominance hierarchy and the dominant individuals gain access to better sources of food and areas of shade.[4] However, kangaroos are not territorial and usually fight only when females are in estrous.

Eastern grey kangaroos adjust their behaviour in relation to the risk of predation with reproductive females, individuals on the periphery of the group and individuals in groups far from cover being the most vigilant.[7] Vigilance in individual kangaroos does not seem to significantly decrease when the size of the group increases. However there is a tendency for the proportion of individuals on the periphery of the group to decline as group size increases.[7] The open membership of the group allows more kangaroos to join and thus provide more buffers against predators.[7]

A mother feeds her joey.
Female (left) and male (right) eastern grey kangaroos

Reproduction[edit]

Females may form strong kinship bonds with their female relatives. Females with living female relatives have a greater chance of reproducing.[8] Most kangaroo births occur during the summer.[9] Eastern grey kangaroos are obligate breeders in that they can only reproduce in one kind of habitat.[10]

The female kangaroo is usually permanently pregnant, except on the day she gives birth; however, she has the ability to freeze the development of an embryo until the previous joey is able to leave the pouch. This is known as diapause, and will occur in times of drought and in areas with poor food sources. The composition of the milk produced by the mother varies according to the needs of the joey. In addition, the mother is able to produce two different kinds of milk simultaneously for the newborn and the older joey still in the pouch.

Mother and joey near a road

Unusually, during a dry period, males will not produce sperm, and females will only conceive if there has been enough rain to produce a large quantity of green vegetation.[11] Females take care of the young without any assistance from the males. The joeys are heavily reliant on their mothers for about 550 days which is when it is weaned. Females sexually mature between 17 and 28 months while males mature at around 25 months.[6]

Status[edit]

It is often said[12][13] that kangaroo populations have increased significantly since the European colonisation of Australia because of the increased areas of grassland (as distinct from forest), the reduction in Dingo numbers, and the availability of artificial watering holes. The estimated population of the species Australia-wide in 2010 was 11.4 million.[14] In some places the eastern grey is so numerous it causes overgrazing and some individual populations have been culled in some parts of Australia (See for example the Eden Park Kangaroo Cull).[15] Despite the commercial harvest and some culls the eastern grey remains common and widespread. It still covers its the entire range it occupied when Europeans arrived in Australia in 1788 [16] and it often comes into conflict with agriculture as it uses the more fertile districts that now carry crops or exotic pasture grasses which kangaroos readily eat.[17]

Gallery[edit]

References[edit]

  1. ^ Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. p. 64. OCLC 62265494. ISBN 0-801-88221-4. 
  2. ^ Munny, P., Menkhorst, P. & Winter, J. (2008). Macropus giganteus. 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
  3. ^ Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. ISBN 978-0-85112-235-9. 
  4. ^ a b c d Dawson, Terence J. (1998). Kangaroos: Biology of the Largest Marsupials. Sydney, Australia: University of New South Wales Press. pp. 12–18. ISBN 0-86840-317-2. 
  5. ^ The Guinness Book of World Records. 2004. p. 53. 
  6. ^ a b c Frith, H. J. and Calaby, J. H. (1969). Kangaroos. Melbourne, Australia: Cheshire Publishing.
  7. ^ a b c d Colagross, A. M. L. and Cockburn, A. (1993). "Vigilance and grouping in the eastern grey kangaroo, Macropus giganteus." Australian Journal of Zoology 41: 325-334.
  8. ^ Jarman, P.J. (1993). "Individual behaviour and social organisation of kangaroos." Physiology and Ecology 29:70-85
  9. ^ Kirkpatrick, T. H. (1965). “Studies of Macropodidae in Queensland. 1. Food preferences of the grey kangaroo (Macropus major Shaw)”. Queensland Journal of Agricultural and Animal Science 22:89-93.
  10. ^ Lee, A. K, and Cockburn, A. (1985). Evolutionary Ecology of Marsupials. Cambridge, UK: Cambridge University Press.
  11. ^ Burnie, David; Don E. Wilson (2001). Animal. New York, New York: DK Publishing, Inc. pp. 99–101. ISBN 0-7894-7764-5. 
  12. ^ [1]
  13. ^ "Kangaroo cull targets millions". BBC News. 21 February 2002. 
  14. ^ http://www.environment.gov.au/biodiversity/wildlife-trade/wild-harvest/kangaroo/population.html#2010
  15. ^ [2][3][4]
  16. ^ Poole, 1983. Eastern Grey Kangaroo, pp. 244-247 In: Strahan R. (Ed). The Australian Museum Complete Book of Australian Mammals, Cornstalk Publishing: Sydney
  17. ^ Edwards,G. 1989. The interaction between macropodids and sheep: a review. pp.795-804 In: Grigg, G., Jarman. P and Hume, I. (Eds.) Kangaroos, wallabies and rat-kangaroos Volume 2. Surrey Beatty and Sons: Syndey
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