Kangaroo bone structure - Large central toe and nail - on right (inside of foot) two toes joined, nails used
for grooming - on right (outer foot) toes used for balance
Kangaroos are large marsupials that are found only in Australia. They are identified by their muscular tails, strong back legs, large feet, short fur and long, pointed ears. Like all marsupials, a sub-type of mammal, females have pouches that contain mammary glands, where their young live until they are old enough to emerge.
Kangaroos are in the Macropodidae family, which also includes tree-kangaroos, wallabies, wallaroos, quokkas and pademelons. When people think of kangaroos, the four species that typically come to mind are in the genus Macropus: the antilopine kangaroo, the red kangaroo, the western gray kangaroo and the eastern gray kangaroo. They are sometimes referred to as the "great kangaroos" because these species are much larger than other kangaroos.
The word Macropod means - Macro, big and Pod means foot so Big Foot.
They have four toes on this big foot, two small ones which are joined together and are used for 'grooming' a central large strong toe with which they use when hopping. This large toes makes a small hole in the earth and when the Kangaroo drops dung which contains seeds, their tail pushes some of the dung into the hole made by their toe and from this new plants emerge.
How Kangaroos Hop
The large, stretchy tendons in a kangaroo’s hind legs act like giant springs. As these tendons strain and contract, they generate most of the energy needed for each hop. This is very different to the way humans jump, which uses a lot of muscular effort.
The tail is also important, acting both as a balancing aid and a counterweight, propelling the animal into each leap. And there’s the added bonus that, while hopping, kangaroos barely need to waste effort on breathing. The jumping motion drives their gut up and down, which inflates and deflates their lungs for them.
Kangaroos usually hop at about 25 kph, though they can reach 70 kph over short distances, covering as much as 9m in a single hop. This energy-efficient way of travelling means they can cover vast distances in search of food and water.
Their long tails, thickened at the base, are used for balancing. This feature is most obvious in the large kangaroos, which use the tail as a third leg when standing still.
In all species, the pouch is well developed, opens forward, and contains four teats. The young kangaroo (“joey”) is born at a very immature stage, when it is only about 2 cm (1 inch) long and weighs less than a gram (0.04 ounce). Immediately after birth, it uses its already clawed and well-developed forelimbs to crawl up the mother’s body and enter the pouch. The joey attaches its mouth to a teat, which then enlarges and holds the young animal in place. After continuous attachment for several weeks, the joey becomes more active and gradually spends more and more time outside the pouch, which it leaves completely at 7 to 10 months of age.
Female macropodidae of many species enter into heat within a few days after giving birth, mating and conception thus occurring while the previous offspring is still in the pouch. After only one week’s development, the microscopic embryo enters a dormant state, called diapause, that lasts until the first joey begins to leave the pouch or until conditions are otherwise favourable. The development of the second embryo then resumes and proceeds to birth after a gestation period of about 30 days. Therefore, the teats are for a while feeding young of very different developmental stages, during which time different teats produce two different compositions of milk.
This is thought to be an adaptation for recovering population numbers quickly after a drought, when breeding ceases and the diapause state is prolonged. In the gray kangaroos, which live in wooded country with a more predictable environment, this system does not exist; there is no diapause, and the pouch is occupied by one young at a time.
The four main Kangaroos we will feature here are those that are slaughtered by the millions every year for the Commercial Kangaroo Industry.
This industry is the largest land based slaughter of wildlife on the planet and a fact that should make the Australian Government hang it's head in shame.
Not only is the Kangaroo an Australian Icon and features on our Coat Of Arms but the name 'Kangaroo' is inextricable linked with Australia, say Australia, think Kangaroo, say Kangaroo, think Australia.
The four Kangaroos featured are knows as 'The big four', they are killed for their skins which are turned into one of the finest leathers, their mat is a by-product and 85% of it goes to the pet food industry to feed cats and dogs. This is an inexcusable waste of a truly unique, gentle animal. See more about the Commercial Industry in our section 'Kangaroo Slaughter'.
The Red Kangaroo (Macropus rufus)
Male Red Kangaroos
Red Joey out of the pouch for a few minutes
Kangaroo mothers are very affectionate
The Red Kangaroo is a large kangaroo with a body length of up to 1.4m and tail up to 1m. Males tend to be orange red in colouring while females are often blue grey. The female is known as a 'Blue Flyer' Both males and females are a lighter whitish colour underneath.
Red Kangaroo’s can be distinguished from other species of kangaroos by the black and white patches on their cheeks and the broad white stripe that extends from the corner of the mouth to ear and has what is known as a 'naked muzzle' (no hair) Their fur is rather short and velvety to the touch Male Red Kangaroos are double the body weight of females and can weigh up to 92 kg while the females can weigh up to 39 kg.
The front limbs of a Red Kangaroo are small and short with heavily-clawed digits. The hind feet are long and extremely powerful enabling the Red Kangaroo to travel at speeds as fast as 65 kph (40mph).
They live in the arid parts of Australia, in the inland woodlands and deserts. Like other marsupials they are well adapted to their arid environment, shutting down their reproductive system when conditions are too dry to breed successfully, and rebooting it only when conditions improve. They are one of the most highly adapted animals to desert conditions, especially their reproductive strategy.
The females usually have a production line of young, one out of the pouch but still drinking milk when necessary, a baby still developing attached to the other nipple, and a fertilised ovum that remains at the blastocyst stage of development until the young attached to the teat reaches the stage were it leaves the pouch, the blastocyst them recommences development. Each nipple varies the composition of the milk it produces to suit the stage of development of the young drinking from them. They don't have a definite breeding season, the female being ready to mate the next time there is a male nearby as soon as the blastocyst resumes development. This reproductive strategy, in which there are young at 3 stages of development allows the female to reproduce at maximum speed in good times and in drought, if she reaches a stage when she can no longer support young, the milk supply stops and, in the most severe conditions, 1 or both of the young feeding from nipples can die, following which the blastocyst resumes development. Each young takes 600 days to reach the stage where it can live independently, but in good times a female can have a young becoming independent every 240 days. There is a high mortality at the stage when they leave the pouch, usually up to 75% never reach adulthood and this is in the 'good times' During drought mortality of juveniles can reach 100%
They drink from stock watering places when available, but they are capable of surviving with no surface water to drink, getting all they need from their food. They usually feed between dusk and dawn, spending the hot part of the day resting in whatever shade they can find. They usually move around in groups of about 20 with a single dominant male. In the dry season mobs of several hundred are not uncommon. They can live more than 20 years, but most don't, many not getting past a couple of years. Their numbers fluctuate widely with the seasonal conditions.
In the hot climate of central Australia the animals need to deal with the heat generated by their metabolic processes, but also a high heat load from the environment, where air temperatures can reach 40oC and solar radiation can reach as high as 126oC. As with most marsupials, kangaroos have a comparatively low standard metabolic rate, SMR, 70 % of the mean for mammals, and a low body temperature, an advantages in a hot, dry climate, as there is less metabolic heat to dissipate. Like the camel, though to a lesser degree, the red kangaroo can allow its body temperature to rise during the day, discharging the excess heat at night, dropping it by 1-3oC soon after dawn, rising 10oC during the day, 35-37oC (McCarron & Dawson, 1989).
Panting has a larger effect on the deep body temperature, especially that of the brain, than sweating, even while the skin temperature remained high as a result of being in contact with the hot air. The nasal turbinals give an indication of the importance of panting in the kangaroos of the desert areas, those of the red kangaroo being much larger than those of the grey kangaroos that inhabit areas with less extreme temperatures (Tyndale-Biscoe, 2005).
In the red kangaroos and euros, sweating takes place only while they are active, stopping when they rest, even if the body temperature is high, but they continue panting. The panting uses water much more efficiently than sweating, conserving water, which only cools the skin, which will soon be reheated by the hot air.
Kangaroos also cool themselves by spreading saliva on their forearms (Dawson, 1973).
Red kangaroos are herbivorous that eat green vegetation. Their main diet are grasses but they also eat forbs and leaves.
It uses its large outward projecting front incisor teeth on the lower jaw to slice through grass and leaves and its large molars at the back of its mouth chop and grinds its food. It spends 43.5% of each day in searching for food grazing and chewing.
Eastern Grey Kangaroo (Macropus giganteus)
Full grown Eastern Grey Male
Who wouldn't love this face?
Small 'Mob' gathers late afternoon
The fur can be anything from a light grey to a fawn, beige colour, the tip of the dail is always darker.
Males: body length to 1.3m, tail to 1m; females: body length to 1m, tail to 0.84m 0.84 - 1.3m
Grey Kangaroos have wide and almost continuous distribution between the inland plains and the coast where the annual rainfall is more than 250mm.
The Eastern Grey Kangaroo is found over most of the eastern states including Tasmania. They are also found at all altitudes in woodlands up to subalpine areas.
They are found in habitats ranging from semi-arid mallee scrub through to woodlands, some farmland areas with remnant vegetation and forest. They tend to favour denser scrubs and forests.
The Eastern Grey Kangaroo is predominantly a grazing animal with specific food preferences. They are herbivorous, favouring grasses but will eat a range of plants, including in some cases, fungi. With the grasses they prefer to eat young green shoots high in protein. Dry grass is difficult for them to digest.
Being nocturnal, large ‘mobs’ will gather at dusk to feed where food is most abundant.They usually rest in the shade or shelter of trees or scrubs moving out to graze from late afternoon to early morning when they will congregate in the open. This is avoiding the hottest part of the day.
They communicate via a series of clucking sounds. Aggressive males and alarmed individuals of both sexes give vent to a guttural cough.
The tendons in the legs of kangaroos act like sprung ropes and help propel the animal at fast speed with minimum effort. The highest recorded speed was set by a female Eastern Grey Kangaroo at 64 km/hr.
Breeding is continuous throughout the year and reaches a peak in summer. The newborn ‘joey’ which weighs less than one gram is born thirty six days after mating. It climbs unaided into the pouch and shortly afterwards attaches to one of the four teats. The young kangaroo is raised in the pouch until it can survive outside. At about 9 months the joey will begin to leave the pouch but continues to suckle from time to time. A joey becomes independent at about 18 months of age.
Western Grey (Macropus fuliginosus)
Male Western Grey
Western Grey Joey, note the lack of fur on the muzzle
Western Grey female
The western grey kangaroo has light grey-brown to dark chocolate-brown fur, a finely-haired muzzle, and large ears, fringed with white hairs. 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. The powerful, enlarged hindquarters enable the familiar leaping mode of locomotion, aided by the long tail, which acts as a balance and a rudder, and by an ankle which is adapted to prevent the foot rotating sideways, so that the kangaroo cannot twist its ankle while hopping . As with all Kangaroos the male western grey kangaroo is much larger than the female, 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. The adult male also has a strong, curry-like odour, lending it the common name of ‘stinker’.
The diet of the western grey kangaroo consists mainly of grasses, as well as some herbs, leaves, tree bark and shrubs and it has a high tolerance to certain plant toxins.
A social species, the western grey kangaroo usually lives in groups, known as ‘mobs’, of up to 40 to 50 individuals.
Old males are usually solitary. In the eastern part of its range, the species may mix with groups of eastern grey kangaroos, although the two usually occur separately due to differing habitat preferences. 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. Although breeding may occur year-round, births usually peak between September and March, after winter rainfall has created maximum vegetation growth.
Female western grey kangaroos become sexually mature at around 20 to 36 months, and males at around 20 to 72 months. Lifespan in the wild may be up to 20 years.
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. Although the female may become receptive as early as 150 days after giving birth, conception does not usually occur until there is enough time before birth for the first young to leave the pouch. However, if the first young dies in the pouch, the female can become receptive again in as little as eight days. 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.
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. The range is strongly associated with the southern winter rainfall belt, and appears to be expanding in South Australia and New South Wales. Its range overlaps that of the eastern grey kangaroo along its extreme eastern edge, in eastern South Australia, western New South Wales and south-western Queensland.
Population numbers for the Western Grey Kangaroo have dropped drastically due the the commercial Kangaroo industry. Numbers are so low in Queensland and NSW that they are no longer on the 'quotas' for yearly killing. The trouble is they are so similar to the Eastern Grey that shooters cannot always distinguish the difference. They have become 'locally' extinct in many areas.
See more about this in our section 'Kangaroo Slaughter'
Wallaroo (Macropus robustus)
Mother and Joey Wallaroo
The word “wallaroo” is a combination (in both word and meaning) of a wallaby and a kangaroo. A kangaroo is generally large and slim-bodied. A wallaby is typically smaller and heavy-set. A wallaroo is right in the middle.
There are many different types of wallaroos. Some are: the Common Wallaroo, the Black Wallaroo, the Antilopine, among others. They can range from 55 to 80 cm in length and 10 to 22 kg in weight.
The Common wallaroo is a kangaroo of a rather stocky build, with coarse, shaggy fur, no hair on its muzzle, a relatively short and thick tail, and a characteristic upright hopping style. Its robust body shape, having shorter limbs than other species of kangaroo, may be an adaptation due to leaping around on rocks, with short, broad hind feet which have roughened soles for extra grip. The male can be up to twice the females size, with particularly thick-set forearms and shoulders.
Wallaroos are mostly solitary and nocturnal, and occupy a relatively small and stable home range close to water or a rocky outcrop, and moving from rough country to feed on shrubs and grasses in adjacent areas. Small groups will sometimes form around valued resources, but these are usually quite loose as regards size and composition. These animals move by hopping on their huge hind legs, moving to new feeding areas that are within their home range. Male wallaroos sometimes fight or "box" with each other, mostly using their powerful feet for kick-boxing until one contestant gives way. Males display dominance like this in order to maintain social hierarchy or gain access to females to mate with. Common wallaroos all interact with each other by grooming, although this behavior is more common between joeys and their mothers.
Wallaroos mate throughout the year. A single joey is born after gestation lasting 30 to 38 days, then the tiny animal must climb up through its mothers fur into her pouch, where it can be nursed. The baby stays in its mother's pouch for protection and feeding and remains inside full time until it is 6 months old. It may occasionally fall out of the pouch, but quickly climbing back in. Weaning usually takes place around the age of 15 to 16 months. The mother waits until weaning before she mates again. Males are usually sexually mature at 18 to 19 months old and females at 22 months old.
Like the Western Grey Kangaroo, the Wallaroo population has dropped to very low numbers due to the commercial kangaroo industry. Wallaroos also are 'locally' extinct in many areas.
Read more about this in our section "Kangaroo Slaughter