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 )
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:
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
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.
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
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
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.
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
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
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
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 ; tactile ; acoustic ; chemical
Eastern grey kangaroos are the only species of kangaroo found in Tasmania. Their population took a sharp decline before laws were passed to protect eastern grey kangaroo populations.
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); sexual ; 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)
The eastern grey kangaroo (Macropus giganteus) is a marsupial found in the eastern third of 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 weighs around 66 kg (146 lb) and stands almost 2 m (6 ft 7 in) tall, the scientific name, Macropus giganteus (gigantic large-foot), is misleading: the red kangaroo of the semi-arid inland is larger, weighing up to 90 kg (200 lb).
The eastern grey kangaroo was described by George Shaw in 1790 as Macropus giganteus.
There are two subspecies:[1]
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). They have a powerful tail that is over 1 m (3 ft 3 in) long in adult males.[4] 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 ft 8 in) 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 ft 7 in) along the curves. When the skin of this specimen was measured it had a "flat" length of 2.49 m (8 ft 2 in).[5]
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 eastern grey kangaroos. Red kangaroos have distinctive markings in black and white beside their muzzles and along the sides of their face. Eastern 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 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.[6] Indigenous Australian names include iyirrbir (Uw Oykangand and Uw Olkola) and kucha (Pakanh).[7] The highest ever recorded speed of any kangaroo was 64 km/h (40 mph) set by a large female eastern grey kangaroo.[8]
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 southern and eastern 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.[9] It also inhabits coastal areas, woodlands, sub-tropical forests, mountain forests, and inland scrubs.[9]
Like all kangaroos, it is mainly nocturnal and crepuscular,[6] and is mostly seen early in the morning, or as the light starts to fade in the evening.[10] 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.[6] 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 their diet.
.jpg)
Eastern grey kangaroos are gregarious and form open-membership groups.[11] The groups contain an average of three individuals.[10] Smaller groups join to graze in preferred foraging areas, and to rest in large groups around the middle of the day.[10] They exist in a dominance hierarchy and the dominant individuals gain access to better sources of food and areas of shade.[6] However, kangaroos are not territorial. 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.[11] 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.[11] The open membership of the group allows more kangaroos to join and thus provide more buffers against predators.[11]
Females may form strong kinship bonds with their relatives. Females with living female relatives have a greater chance of reproducing.[12] Most kangaroo births occur during the summer.[13] Eastern grey kangaroos are obligate breeders in that they can reproduce in only one kind of habitat.[14]
The female eastern grey 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 embryonic 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. Unusually, during a dry period, males will not produce sperm, and females will conceive only if there has been enough rain to produce a large quantity of green vegetation.[15] 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 they are weaned. Females sexually mature between 17 and 28 months, while males mature at around 25 months.[9]
It is popularly thought, but not confirmed by evidence,[16][17] 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.[18] 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).[19][20][21] Despite the commercial harvest and some culls, the eastern grey remains common and widespread. Eastern greys are common in suburban and rural areas where they have been observed to form larger groups than in natural areas.[22] It still covers the entire range it occupied when Europeans arrived in Australia in 1788[23] 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.[24] Kangaroo meat has also been considered to replace beef in recent years, as their soft feet are preferable to hooves in erosion prone areas.[25]
The eastern grey kangaroo (Macropus giganteus) is a marsupial found in the eastern third of 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 weighs around 66 kg (146 lb) and stands almost 2 m (6 ft 7 in) tall, the scientific name, Macropus giganteus (gigantic large-foot), is misleading: the red kangaroo of the semi-arid inland is larger, weighing up to 90 kg (200 lb).
.jpg)
