Eastern Grey Kangaroo
Encyclopedia
The Eastern Grey Kangaroo (Macropus giganteus) is a marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...

 found in southern and eastern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, 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
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...

 (weight 145 lb.
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

) and stands almost 2 m (6 ft.) tall, the scientific name, Macropus giganteus (gigantic large-foot), is misleading, as the Red Kangaroo
Red Kangaroo
The Red Kangaroo is the largest of all kangaroos, the largest mammal native to Australia, and the largest surviving marsupial. It is found across mainland Australia, avoiding only the more fertile areas in the south, the east coast, and the northern rainforests.-Description:This species is a very...

 of the semi-arid inland is, at 85 kg, larger.

Description

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 to 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
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...

 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 shape 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 to 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. Indigenous Australian
Indigenous Australians
Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....

 names include iyirrbir (Uw Oykangand
Uw Oykangand language
Kunjen is a Paman language spoken on the Cape York Peninsula of Queensland, Australia, by the Uw Olkola and Uw Oykangand people. The two dialects, Uw Olkola and Uw Oykangand, are very close, being mutually intelligible and sharing 97% of their core vocabulary.A small dictionary of Kunjen has been...

 and Uw Olkola) and kucha (Pakanh). The highest ever recorded speed of any kangaroo was 64 kilometres per hour (39.8 mph) set by a large female Eastern Grey Kangaroo.

Ecology

Although the Red is better known by reputation, the Eastern Grey is the species most commonly seen and 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. It prefers open grassland with areas of bush for daytime shelter and mainly inhabits wetter parts of Australia. It also inhabits coastal areas, woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...

s, sub-tropical forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

s, mountain forests, and inland scrubs.

Like all kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...

s, it is mainly nocturnal and crepuscular
Crepuscular
Crepuscular animals are those that are active primarily during twilight, that is during dawn and dusk. The word is derived from the Latin word crepusculum, meaning "twilight." Crepuscular is, thus, in contrast with diurnal and nocturnal behavior. Crepuscular animals may also be active on a bright...

, 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 can out in the open to feed on the grasslands in large numbers. 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

Eastern grey kangaroos are gregarious and form open-membership groups. 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. However, kangaroos are not territorial and usually fight only when females are in estrous. Dominant males rarely stay dominant over a year and it is not uncommon for one to die shortly after changes in environmental conditions. Dominant male kangaroos rarely keep their position for more than a year.

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. 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. The open membership of the group allows more kangaroos to join and thus provide more buffers against predators.

Reproduction

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

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
Embryonic diapause
Delayed Implantation or Embryonic Diapause is a reproductive strategy used by approximately 100 different mammals in seven or eight different orders. In embryonic diapause, the embryo does not immediately implant in the uterus, but is maintained in a state of dormancy. Little to no development...

, and will occur in times of drought and in areas with poor food sources. The composition of the milk
Milk
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...

 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.
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. 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.

Status

It is often said 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
Dingo
The Australian Dingo or Warrigal is a free-roaming wild dog unique to the continent of Australia, mainly found in the outback. Its original ancestors are thought to have arrived with humans from southeast Asia thousands of years ago, when dogs were still relatively undomesticated and closer to...

 numbers, and the availability of artificial watering holes. The current estimated population of the species numbers two million. Because of this, the Eastern Grey has begun to be culled in some parts of Australia (See for example the Eden Park Kangaroo Cull
Eden Park Kangaroo Cull
During October 2010 the Northern Melbourne Institute of TAFE applied for and received a 12 month permit from the Victorian Department of Sustainability and Environment for the Eden Park Kangaroo Cull - to cull 300 Eastern Grey Kangaroos on its 320 hectare Eden Park Vineyard and farm and Northern...

).
While the Eastern Grey remains common, there are vast areas of country from which it has been exterminated (in general, it avoids humans), and most of the more fertile districts now carry crops or exotic pasture grasses which kangaroos tend not to eat. (One of the easiest ways to find kangaroos is to look for patches of remnant native grassland.)

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