Highspeed leaping

Kangaroo locomotion. (Illustration by Marguette Dongvillo)

powerful hind limbs, the forelimbs of most macropodids are small and rather weakly developed. In the larger species where there is distinct size dimorphism between males and females, the forelimbs of males show a disproportionate amount of development for the purposes of display and fighting. The fore-limbs of the tree kangaroos are also relatively more developed than in other genera to aid in climbing. As a consequence of the large number of species included within the family, there is an enormous size range with the group. At the smallest end of the scale are species such as the hare-wallabies that have adult head-body lengths of only 11 in (290 mm) and weigh only 3 lb (1.4 kg). At the other end are the large gray kangaroos with adult head-body lengths up to 91 in (2,300 mm) and weighing up to 187 lb (85 kg). There is also significant variation in the fur color and patterning both between and within species in the family Macropodidae. Colors range from sandy red through to black and there is a huge range of intermediate colors and mixes. Many species have distinct stripes or markings in the form of either back stripes, thigh and shoulder patches/flashes, and eye lines or patches. A few of the tree kangaroo and rock wallaby species also display distinct tail stripes.


Representatives of the Macropodidae family are broadly distributed all over Australia and through regions of New

Kangaroo development. 1. A female kangaroo in the birthing position. 1a. The joey is born still enclosed within the amnion, and is equipped with sharp claws to break through it. 1b. The joey climbs to the pouch using its forelimbs. 1c. For several months the joey nurses and develops inside the pouch. 2. A joey at the stage of semi-independence; it can leave the pouch, but returns to nurse and rest. 3. A young kangaroo at the young-at-foot stage; it can no longer return to the pouch, but continues to nurse. (Illustration by Marguette Dongvillo)

Kangaroo development. 1. A female kangaroo in the birthing position. 1a. The joey is born still enclosed within the amnion, and is equipped with sharp claws to break through it. 1b. The joey climbs to the pouch using its forelimbs. 1c. For several months the joey nurses and develops inside the pouch. 2. A joey at the stage of semi-independence; it can leave the pouch, but returns to nurse and rest. 3. A young kangaroo at the young-at-foot stage; it can no longer return to the pouch, but continues to nurse. (Illustration by Marguette Dongvillo)

Guinea, Irian Jaya, and several Indonesian islands. Of the 11 genera within the family, six are restricted to Australia: Wallabia, Setonix, Petrogale, Onychogalea, Lagorchestes, and Lagostrophus. The large and diverse Macropus genus is almost confined to Australia, with the agile wallaby being the only species that occurs naturally outside Australia. Two genera, Dorcopsisand Dorcopsulus, are restricted to the New Guinea/ Indonesia region. A range of other species, including eight of the 10 Dendrolagus tree kangaroos, and three of the six Thy-logale pademelons, are also found only in that region. In addition to their widespread natural occurrence, several species have been introduced into other regions of the world, in cluding Britain, Germany, Hawaii, and New Zealand. Self-sustaining populations of brush-tailed rock wallaby continue to persist on the islands of Oahu (Hawaii) and Kawau, Ran-gitoto, and Motutapu (New Zealand).


Kangaroos, wallabies, and tree kangaroos are represented in almost all habitat types in Australia and New Guinea, including alpine grasslands, high-altitude rainforests, spinifex deserts, and coastal savannahs. Many habitat types support four

The Matschie's tree kangaroo (Dendrolagus matschiei) is found in central and eastern New Guinea. (Photo by Animals Animals ©Michael Dick. Reproduced by permission.)

or more species, and some woodland and forested areas along Australia's eastern Dividing Range are known to support as many as 12 different kangaroo and wallaby species. Some degree of habitat specificity occurs within particular macropodid

A Bennett's tree kangaroo (Dendrolagus bennettianus) surveys from the trees. (Photo by Animals Animals ©Fritz Prenzel. Reproduced by permission.)

genera. The New Guinea forest wallabies (Dorcopsis and Dor-copsulus) and the tree kangaroos (Dendrolagus) are restricted to rainforest habitats in the northern tropics of Australia and New Guinea. While the pademelons (Thylogale) also have an association with moist forests, they inhabit a broader range of forest types distributed from New Guinea to Tasmania. The rock wallabies (Petrogale) occur in habitats ranging from the arid zone to the wet tropics, but always have a close association with rocky hillsides, boulder piles, or cliff lines. The remaining genera have less well-defined habitat associations. The hare-wallabies (Lagorchestes) and the nail-tailed wallabies (Ony-chogalea) are found in arid and semi-arid habitats as diverse as Triodia grasslands, Acacia shrublands, and savannas. The genus Macropus is undoubtedly the most cosmopolitan with respect to habitats, with members of the genus occurring in most habitat types across Australia as well as in New Guinea.


The general patterns of dispersion and social organization within the Macropodidae share a reasonably common trend

A Bennett's tree kangaroo (Dendrolagus bennettianus) surveys from the trees. (Photo by Animals Animals ©Fritz Prenzel. Reproduced by permission.)

Whiptail wallabies (Macropus parryi) have distinctive cheek marks. (Photo by R. Kopfle. Bruce Coleman, Inc. Reproduced by permission.)
Red-necked wallabies (Macropus rufogriseus) fighting in Queensland, Australia. (Photo by J & D Bartlett. Bruce Coleman, Inc. Reproduced by permission.)

with like-sized bovids and cervids, whereby the small, selective feeders tend to be dispersed and solitary and the large nonselective grazers tend to be aggregated and gregarious. This pattern is most obvious in the tendency of some of the larger species within the genus Macropus to form groups (often called "mobs") that may contain 50 of more animals. While there is some social organization within these groups, it is extremely flexible with age/sex classes intermingling, feeding ranges not defended, and mating being promiscuous. The pat-

A Parma wallaby (Macropus parma) eating grass while concealed in its typical reedy habitat. (Photo by Rod Williams. Bruce Coleman, Inc. Reproduced by permission.)

terns of association of age/sex classes have been studied for a number of different species within the Macropodiae. In general, females were found to relate to the distribution of their resources in a way that maximizes their chances of successfully rearing young. Males, in comparison, overlap the distribution of females such that high status individuals gain greater access to mating opportunities. In the medium and large species, a male's status is based largely on size and this is the principal factor influencing males' mating success. This male hierarchy is extremely dynamic, and aggressive interactions between males in both solitary and gregarious species occur regularly in order to establish individual status. These aggressive interactions are quite ritualized in the larger and more sexually dimorphic species. Many of the smaller species adopt an activity pattern that is either nocturnal or crespuscular, a strategy they adopt to avoid predation and, in some cases, the harshness of hot and dry environments. Most of the larger species are active throughout the day, but their activity peaks around dawn and dusk. The social grouping displayed by larger species provides some security from predation that is absent in the more solitary species.

An eastern gray kangaroo (Macropus giganteus) eating an ice cream cone at an animal farm in Australia. (Photo by Animals Animals ©Mickey Gibson. Reproduced by permission.)

Feeding ecology and diet

The kangaroos, wallabies, and tree kangaroos are predominantly herbivorous, although some of the smaller species will eat invertebrates and fungi. In general, the smaller species tend to be more selective in their feeding habits than the larger species. Smaller species such as the hare-wallabies and nail-tailed wallabies preferentially seek out scattered, high-quality food items such as seeds, fruits, and actively growing plants. In contrast, the larger kangaroos are better able to process lower-quality food items and can incorporate a wide range of plants. An enlarged fore stomach in macropodids performs in a similar way to the rumen in eutherian grazing species and enables kangaroos and wallabies to digest low-quality food. Some of the large plains kangaroos rely almost entirely on grasses. Food availability is clearly influenced by habitat productivity and seasonal conditions. The diets of species that occupy moist forest habitats, therefore, generally include more fruits and dicot leaves compared to the diets of species occupying more arid habitats. The dramatic effects of season ensure that most species adopt an opportunistic feeding strategy that takes advantage of particular feed resources that may be available in the environment for only limited periods.

Reproductive biology

The mating system is promiscuous. The age at which kangaroos, wallabies, and tree kangaroos reach sexual maturity

A red kangaroo (Macropus rufus) with nursing joey. (Photo by Animals Animals ©Frutz Prenzel. Reproduced by permission.)

is strongly correlated with adult body size. Females of the larger kangaroo species can breed at two to three years, whereas in some of the smaller species, females can conceive at or slightly before the time of weaning at four to five months. In most cases, males reach sexual maturity some

Agile wallabies (Macropus agilis) congregating at a waterhole in Irian Jaya. (Photo by Harald Schütz. Reproduced by permission.) 88 Grzimek's Animal Life Encyclopedia
Tiny baby red kangaroo (Macropus rufus) in its mother's pouch. (Photo by Animals Animals ©A. Root, OSF. Reproduced by permission.)

time after the females, and in some species their participation in mating is further delayed due to social dynamics within cohorts. The larger species exhibit significant sexual size dim-porphism, as larger males are able to get the majority of mating opportunities. This dimorphism is less prominent in the smaller species where males and females reach the same adult size. All the macropodids produce only a single young at a birth. Most species exhibit the reproductive phenomenon of embryonic dipause, in which the development of a new embryo is halted at an unimplanted blastocyst stage until about a month before an existing pouch-young permanently vacates the mother pouch. This reproductive adaptation effectively reduces the time interval between births and enables macrop-odids to respond quickly to both favorable seasonal conditions and to the loss of an existing young. While all species appear to be capable of producing young at all times throughout the year, some species have distinct breeding seasons, most probably in response to seasonal conditions. Like other members of the subclass Marsupialia, kangaroos, wallabies, and tree kangaroos give birth to tiny (0.2-0.6 in [0.5-1.5 cm]), unfurred young in which the tail, hind limbs, and eyes are not fully developed. At birth, this macropodid neonate uses its strong forelimbs to clamber from its mother's cloacal opening to a teat inside her forward-opening pouch. The neonate attaches to the mother until it is relatively well developed. The duration of the pouch life varies between species from 180 to 320 days. Having vacated the pouch, the young-at-foot will continue to suckle from the mother for between one to six months. This young-at-foot stage is longer in the larger species, and may be virtually absent in some of the smaller species.

Conservation status

The conservation status of the Macropodidae has altered greatly in modern times, principally in response to human disturbances associated with European colonization and development of Australia and New Guinea. Of the 62 modern species described for the family, four are now Extinct, one species is Critically Endangered, seven species are Endangered, and a further 18 species are considered to be Vulnerable or Near Threatened. Smaller species from the more arid regions have faired worse and account for three of the four Extinct species. The primary causes for these declines include loss of habitat, competition from herbivores such as the introduced European rabbit, sheep, and goat, and predation by introduced carnivores such as the red fox and cat. The impacts of habitat loss have been particularly severe for several of the New Guinea tree kangaroo species, as rainforest areas are cleared for forestry and agriculture. In contrast to the situation with the smaller species, European settlement has had little impact on the larger kangaroos and wallabies. A number of the larger species may in fact have increased in range and numbers in response to both the clearing of native vegetation for the establishment of pastures and the provision of artificial watering points for domestic livestock. Comparisons between historical accounts and recent surveys suggest that species such as the red kangaroo, eastern gray kangaroo, western gray kangaroo, and common wallaroo may now be more abundant than at the time of European settlement of Australia.

Significance to humans

Rock art in Australia's Arnhem Land plateau clearly depicts a number of kangaroo and wallaby species that were used

A tammar wallaby (Macropus eugenii) mother with joey, Kangaroo Island, South Australia. (Photo by Daniel Zupanc. Bruce Coleman, Inc. Reproduced by permission.)

by Australian Aborigines. Characteristics of species were generally emphasized in these drawings, which date to 20,000 years before present. These very early pictorial records provide useful information on past distributions of some macro-pod species and give an indication of the long history of human exploitation. The Aborigines considered the unique Australian wildlife both as a food source and as "partners" in the land. Macropods were the principal animal group consistently exploited by Aborigines. In addition to their use as a food resource, kangaroos and wallabies also feature prominently in traditional dreamtime stories and were culturally significant. Tim Flannery provides detailed accounts of traditional uses of kangaroos and wallabies by New Guinea natives. Early European settlers and pastoralists in both Australia and New Guinea initially valued kangaroos and wallabies as sources of food and hides. It was not long, however, before sheep ranch ers regarded macropods as competitors for stock fodder. A trade in macropod skins developed in the mid-nineteenth century. By this time, the large macropods were considered a pest by pastoralists in New South Wales and Queensland, and killing was required by legislation. This legal harvesting was the precursor to the current commercial harvesting of kangaroos that sees some two to four million red kangaroos, eastern and western gray kangaroos, and common wallaroos shot every year in Australia. This modern harvest is strictly monitored and regulated and, for the most part, humane. Population monitoring and a sustainable quota system are used to avoid overexploitation. Kangaroos are a quintessential part Australia's national and international identity. They feature prominently in coats of arms, flags, and corporate logos, and are the principal wildlife experience sought by inbound tourists to Australia.

1. Agile wallaby (Macropus agilis); 2. Parma wallaby (Macropus parma); 3. Bennett's tree kangaroo (Dendrolagus bennettianus); 4. Rufous hare-wallaby (Lagorchestes hirsutus); 5. Matschie's tree kangaroo (Dendrolagus matschiei); 6. Banded hare-wallaby (Lagostrophus fasciatus); 7. Gray dorcopsis (Dorcopsis luctuosa); 8. Papuan forest wallaby (Dorcopsulus macleayi); 9. Eastern gray kangaroo (Macropus giganteus); 10. Red kangaroo (Macropus rufus). (Illustration by Marguette Dongvillo)

1. Bridled nail-tailed wallaby (Onychogalea fraenata); 2. Brush-tailed rock wallaby (Petrogale penicillata); 3. Swamp wallaby (Wallabia bicolor); 4. Nabarlek (Petrogale concinna); 5. Red-legged pademelon (Thylogale stigmatica); 6. Yellow-footed rock wallaby (Petrogale xanthopus); 7. Quokka (Setonix brachyurus). (Illustration by Marguette Donvillo)

Pregnancy And Childbirth

Pregnancy And Childbirth

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