One of the largest and most abundant of all kangaroos, the western grey kangaroo has light grey-brown to dark chocolate-brown fur, a finely-haired muzzle, and large ears, fringed with white hairs (2) (3) (4). The fur is often flecked with grey above and is paler below, with dark feet and forepaws, a black tip to the tail, and buff patches on the legs and forearms (4). The powerful, enlarged hindquarters enable the familiar leaping mode of locomotion, aided by the long tail, which acts as a balance and a rudder (2), and by an ankle which is adapted to prevent the foot rotating sideways, so that the kangaroo cannot twist its ankle while hopping (5). The male western grey kangaroo is much larger than the female (4), with longer and more muscular shoulders and forearms, more heavily clawed forepaws, and thickened skin over the belly, which helps absorb the impact of kicks during fights (5). The adult male also has a strong, curry-like odour, lending it the common name of 'stinker' (3). Two subspecies of western grey kangaroo are recognised (3) (6). Macropus fuliginosus fuliginosus, the Kangaroo Island western grey kangaroo, is a dark sooty brown on the back, with shorter limbs, ears and tail. Macropus fuliginosus melanops is variable across its mainland range, being stockier in the east and south, with darker brown on the head and back, and bluish-grey fur underneath. Although previously divided into two forms, M. f. melanops and M. f. ocydromus, this subspecies is now known to form a single, gradually changing population, or cline, across its range (3). The western grey kangaroo can be distinguished from the closely related eastern grey kangaroo, Macropus giganteus, by its browner fur, darker colouration around the head, and sometimes by a blackish patch around the elbow (3).

The western grey kangaroo is most active from late afternoon to early morning, resting during the day in the shelter of trees and shrubs. When moving slowly, such as when feeding, kangaroos show an unusual, 'five-footed' gait, balancing on the tail and forearms while swinging the hind legs forward (2). The diet of the western grey kangaroo consists mainly of grasses, as well as some herbs, leaves, tree bark and shrubs (2) (4), and it has a high tolerance to certain plant toxins (3). A social species, the western grey kangaroo usually lives in groups, known as 'mobs', of around 40 to 50 individuals. Old males are usually solitary (4). The species may mix with groups of eastern grey kangaroos, although the two usually occur separately due to differing habitat preferences (3). During the autumn and winter, male western grey kangaroos live in large groups away from the females and engage in threat displays and fights to establish dominance, with the largest, most dominant males having first access to the females in the spring (7). Although breeding may occur year-round, births usually peak between September and March, after winter rainfall has created maximum vegetation growth (2) (4) (7) (8). After a gestation of just 30 days (2) (4), the single, tiny newborn climbs unaided through the female's fur and into the forward-facing pouch, where it attaches to one of four teats (4) (5). In common with other marsupials, most development occurs in the pouch, with the young, or 'joey', first emerging after around 280 days (7), and suckling until about 17 months old (4). Female western grey kangaroos become sexually mature at around 20 to 36 months, and males at around 20 to 72 months (2). Lifespan in the wild may be up to 20 years (4). Somewhat unusually for a kangaroo, the female western grey kangaroo does not carry dormant embryos in the uterus while still suckling the first young in the pouch, a behaviour known as embryonic diapause (2) (7). Although the female may become receptive as early as 150 days after giving birth (2) (9), conception does not usually occur until there is enough time before birth for the first young to leave the pouch (2). However, if the first young dies in the pouch, the female can become receptive again in as little as eight days (2) (9). Although the lack of embryonic diapause means that the western grey kangaroo is unable, like other species, to recover quickly from drought by rapidly replacing lost young, its seasonal breeding is an advantage where winter rainfall and new spring growth are predictable (7).

This species is endemic to southern Australia, where it is widespread from the Indian Ocean in the west to western Victoria and New South Wales (Coulson 2008). The subspecies Macropus fuliginosus fuliginosus is endemic to Kangaroo Island (South Australia). The range is expanding in mainland South Australia, and expanding eastward within New South Wales.

This species of kangaroo is found in the southern part of the continent of Australia including southern Queensland, southern New South Wales, and western Victoria. In addition, it is found on Kangaroo Island off of the southern coast of Australia.

Biogeographic Regions: australian (Native )

The western grey kangaroo, somewhat contrary to its common name, is found throughout the south of Australia, from the Indian Ocean in Western Australia to western Victoria, New South Wales and southern Queensland. M. f. fuliginosus is endemic to Kangaroo Island, off the coast of South Australia, while M. f. melanops occurs on the mainland (1) (2) (3). The range is strongly associated with the southern winter rainfall belt (3), and appears to be expanding in South Australia and New South Wales (1).

This species exhibits sexual dimorphism, whereby males are larger than females. Western grey kangaroos vary in color from light brown to reddish shades of dark brown. They have a pale throat, chest and abdomen. The muzzle is distinctly different from other kangaroo species in that it is covered with much finer hair. These kangaroos can grow to be as large as 7 ft. tall. The tail is used as a balance in locomotion. Tail length ranges from 425-1000mm in males and 438-815mm in females. Muscle mass makes up approximately 80% of the body weight for this species.

Range mass: 3 to 53.5 kg.

Range length: 946 to 2225 mm.

Other Physical Features: endothermic ; bilateral symmetry

Habitat and Ecology

Systems

• Terrestrial

Western grey kangaroos are capable of using several different types of habitats. They can be found in woodlands, open forests, coastal heathland, and open grassland areas. They have also been found near city areas and on golf courses. These kangaroos prefer areas with heterogeneous habitats, because these areas are the most likely to meet their requirements for food and cover.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest ; scrub forest

Other Habitat Features: urban ; agricultural

This species occurs in open woodland and forest, scrubland, heath and grassland, and is also found in pastureland and in cleared farmland adjacent to native bush (1) (4) (6).

Western grey kangaroos eat grasses, forbs, leaves, tree bark, and shrubby browse. They use microorganisms in an organ called the cecum to digest the cellulose of plants. This kangaroo requires very little water and is able to survive on plants high in fiber. Western grey kangaroos spend between 6 and 10 hours grazing per day, mostly at dawn and dusk. In captivity, these kangaroos are often fed a pelleted grain or hay.

Plant Foods: leaves; wood, bark, or stems

Primary Diet: herbivore (Folivore )

The western grey kangaroo controls vegetation growth by feeding on grasses and forbs.

The dingo (Canis familiaris dingo) preys upon the western grey kangaroo. Healthy large males are usually not preyed upon by the dingo because of their size. However, young and old age classes are vulnerable to predation by the dingo.

Known Predators:

• dingos (Canis lupus dingo)

Macropus fuliginosus is prey of:
Canis lupus dingo

This list may not be complete but is based on published studies.

Western grey kangaroos have lived to be upward of 20 years old in captivity. However, the maximum lifespan of these kangaroos in the wild is approximately 10 years.

Range lifespan

Status: wild: 10 (high) years.

Range lifespan

Status: captivity: 20 (high) years.

Average lifespan

Status: wild: 20.0 years.

Maximum longevity: 23.2 years (captivity) Observations: In the wild these animals have been estimated to live up to 20 years (Bernhard Grzimek 1990). One specimen lived 23.2 years in captivity (Richard Weigl 2005).

Males compete for females, whereby dominant males mate. Dominancy is determined through "boxing", which is a form of male competition.

Mating System: polygynous

Western grey kangaroos can breed continuously, but a peak in reproductive activity exists in the seasons of spring and summer. Sexual maturity is reached at approximately 20 months for males and 17 months for females. Females have an oestrous cycle of approximately 35 days. Interestingly, the western grey kangaroo is not capable of embryonic diapause. Usually, only a single offsping weighing approximately 0.8g is born after a mean gestation period of 30.5 days. The offsping, commonly called a joey, will climb from the birth canal to the pouch where it grabs hold of a teat and nurses. The joey will begin to leave the pouch after an average of 46 weeks, and may continue to nurse from the pouch for up to an additional 6 months after leaving the pouch. After the joey has left the pouch, the female is capable of mating again.

Breeding season: year round with a peak in spring and summer

Range number of offspring: 1 to 1.

Average gestation period: 30.5 days.

Average weaning age: 18 months.

Average age at sexual or reproductive maturity (female): 17 months.

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

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 0.93433 g.

Average gestation period: 30 days.

Average number of offspring: 1.

Average age at sexual or reproductive maturity (male)

Sex: male: 880 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 670 days.

Generally, exclusively the female cares for the young.

Parental Investment: altricial ; female parental care

Despite the crop damage from this kangaroo species, it is a protected species and is controlled exclusively by the state faunal authorities. In 1987, there was an estimated population of 1.7 million western grey kangaroos. Permits to harvest the western grey kangaroo are issued in areas where this species interferes with successful agricultural operations or management programs to rehabilitate vegetation communities.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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

Population

Population Trend

Major Threats

The western grey kangaroo is still abundant over most of its original range, and the population may even been expanding (1), helped in part by the provision of pasture and artificial water holes for domestic livestock, together with a reduction in dingo numbers (2) (3) (5). However, the species may be disadvantaged by the spread of extensive agriculture, particularly where land has been cleared for cereal crops (3), and may also have disappeared from many densely settled areas (2). On Kangaroo Island, M. f. fuliginosus may be subject to habitat loss as human activity increases within its limited range, and many animals are also killed by increasing tourist traffic on the island's roads (2) (6). Despite these threats, the western grey kangaroo is so numerous in some areas that it is considered a pest species, viewed as a competitor for pasture and water with domestic sheep and cattle (10) (11). Millions of kangaroos are culled each year, under licence, to prevent damage to crops or pasture (1) (5) (6). In addition, regulated commercial hunting is permitted, with kangaroo meat considered a high quality game meat, low in both fat and cholesterol, and the skins providing a high quality, durable leather. Kangaroo products are sold both within Australia and exported overseas (10). However, there is controversy over whether kangaroo populations can sustain present hunting levels, especially in the face of increasing human habitat modification and drought (2).

Conservation Actions

With its wide distribution, large population and presence in many protected areas, the western grey kangaroo is not currently considered at risk of extinction (1). Like other kangaroos, wallabies and wallaroos, the species is protected by law in Australia (1) (11), and hunting is not permitted within protected areas (10). The species also has the longest running monitoring programme of any Australian vertebrate (1). Hunting permits and commercial harvesting are controlled under nationally approved management plans, which aim to maintain kangaroo populations over their natural range and manage them as a renewable resource, in an ecologically sustainable manner (10) (12) (13) (14). In addition, it has been suggested that farmers be encouraged to shift focus from sheep-rearing to kangaroo harvesting, which may help to reduce land degradation (10). Recommended conservation actions for the Kangaroo Island subspecies also include monitoring the number of animals killed along the island's roads (6). As an appealing, well-known and readily identifiable Australian mammal, much controversy and public debate has surrounded the commercial hunting of the western grey kangaroo. This scrutiny has led to close attention being given to appropriate kangaroo management, based on extensive scientific research (11), and, although still controversial, such sustainable use may prove a valuable conservation tool where wildlife and human land-use requirements increasingly conflict.

Crops and pasteurs may be damaged by western grey kangaroos through their foraging in these areas.

Negative Impacts: crop pest

Tourists enjoy viewing this species of kangaroo on golf courses and in national parks. Australian kangaroo meat is marketed throughout the world as a quality game meat.

Positive Impacts: food ; ecotourism