Wallaby

A wallaby is a small or middle-sized macropod native to Australia and New Guinea, with introduced populations in New Zealand, Hawaii and the United Kingdom. It belongs to the same family as kangaroos, and the term is an informal one for macropods smaller than a kangaroo or wallaroo. Groups include brush wallabies, rock-wallabies that live among rocks usually near water, hare-wallabies, nail-tails, pademelons and the quokka. Wallabies are herbivores that eat grasses, vegetables, leaves and other foliage, and they cover vast distances for food and water, often gathering in mobs at the same water hole in the dry season. Their powerful hind legs bound at speed and deliver kicks.

About the wallaby

A wallaby is a small or medium-sized macropod, a hopping marsupial in the same family as kangaroos, native to Australia and New Guinea. "Wallaby" is an informal name rather than a single species: it covers dozens of macropods smaller than kangaroos and wallaroos, from brush wallabies and rock-wallabies to pademelons and the quokka.

Because the word is informal, wallabies do not form a single genetic group. The brush wallabies of the genus Notamacropus, such as the agile wallaby and the red-necked wallaby, are the closest relatives of kangaroos and look much like them apart from size. The 19 or so rock-wallabies of the genus Petrogale are specialists of cliffs and boulders. Other groups include hare-wallabies, nail-tail wallabies, pademelons, the swamp wallaby, the New Guinea dorcopsises and the quokka. The name itself comes from the Dharug words walabi or waliba, and an early English name was "brush-kangaroo."

Brush wallabies are the ones most often seen in the wild, and a well-known example is the red-necked wallaby, or Bennett's wallaby, scientific name Notamacropus rufogriseus. It has a grizzled grey coat with a reddish wash across the shoulders, a black nose and paws and a white stripe on the upper lip. Adults weigh 13.8–18.6 kg (30–41 lb) and reach about 90 cm (35 in) in head-and-body length, with males usually larger than females. The tammar wallaby is another brush wallaby.

Size across the group varies a lot. Brush wallabies measure 45–105 cm (18–41 in) in head and body, plus a tail of 33–75 cm (13–30 in). The smallest known species, the dwarf wallaby of New Guinea, is about 46 cm (18 in) from nose to tail tip and weighs about 1.6 kg (3.5 lb). The largest wallabies approach 2 m (6.6 ft) including the tail.

Like all macropods, a name that means "large foot," wallabies have long, narrow hind feet with a very large fourth toe, short front legs with five separate fingers, a small head and a long, muscular tail used mostly for balance and support. Females carry their young in a pouch that opens forward. Nail-tail wallabies even have a horny spur at the tip of the tail, though its function is unknown.

Behavior and diet

Wallabies are herbivores. They eat a wide range of grasses, leaves, weeds and other foliage, and red-necked wallabies also eat roots. Like other macropods they have broad cutting teeth at the front, no canines and a gap before the molars. The molars erupt a pair at a time from the back of the jaw over the animal's life, replacing worn ones as tough grasses grind them down.

Digestion works much like that of cattle and sheep, though the anatomy differs. Microbes in the first chamber of a complex stomach break down fibrous plant material. Food passes through quickly, which helps explain why wallabies release relatively little methane. In the dry season, when food and water are scarce, wallabies may travel long distances, and mobs often gather at the same waterhole. As towns spread, many now feed in semi-rural and urban areas.

The hind legs do more than move the animal. Wallabies use them for fast bounding, high jumps and hard kicks against predators. Their tendons store elastic energy, so much of the power for each hop comes from spring action rather than muscle. In the tammar wallaby, without that tendon storage, the metabolic rate might be 30–50% higher. Hopping is even tied to breathing: lifting off pushes air out of the lungs and landing draws it back in, and carrying extra weight, such as a heavy joey, costs little more energy.

Red-necked wallabies are mostly solitary and nocturnal, resting through the day and gathering only where food, water or shelter is plentiful. When they do group up, they form a social hierarchy, and research shows they patch up fights by reuniting and making friendly contact afterward.

Breeding is typical of macropods. Gestation lasts about a month, and usually a single young is born weighing less than 1 g (0.035 oz). It crawls to one of four teats in the pouch and stays there for 5–11 months, about 280 days in the red-necked wallaby. Young are weaned two to six months after leaving the pouch and mature at one to three years. Young wallabies are called joeys, adult males bucks, boomers or jacks, and adult females does, flyers or jills.

Range and habitat

Wallabies are found across Australia, Tasmania and New Guinea. In Australia they favor remote, heavily timbered or rugged areas, and are less common on the semi-arid plains better suited to larger kangaroos. Rock-wallabies live among rocks, usually near water, with feet that grip by skin friction rather than claws. The red-necked wallaby lives in coastal scrub and sclerophyll forest across eastern Australia from Bundaberg, Queensland, to the South Australian border, and in Tasmania and the Bass Strait islands.

Several species have been introduced elsewhere and now breed in the wild. Kawau Island in New Zealand has had tammar, parma, swamp and brush-tailed rock-wallabies since about 1870, and the South Canterbury region holds a large population of red-necked wallabies. Free-living red-necked wallabies also live on the Isle of Man, on an island in Scotland's Loch Lomond, on Lambay Island off Ireland and in a forest west of Paris. In the U.S., a small population of brush-tailed rock-wallabies has lived in Oahu's Kalihi Valley, Hawaii, since captive animals escaped in 1916.

Wallaby vs kangaroo

Wallabies and kangaroos are in the same family, and brush wallabies are close kangaroo relatives. The difference is mostly size and habitat.

The red kangaroo and western grey kangaroo are two of the kangaroos in the same family.

Conservation status

There is no single IUCN status for wallabies, because each species is assessed separately. The red-necked wallaby is listed as Least Concern, and its numbers in Tasmania and coastal Queensland have grown over recent decades as hunting eased and patchy forest clearing created pasture next to cover. Other wallabies are far worse off. Several rock-wallabies are endangered, and the toolache wallaby, eastern hare-wallaby, Lake Mackay hare-wallaby and crescent nail-tail wallaby are extinct. The parma wallaby was thought extinct for 100 years before it was rediscovered.

Threats include predators such as dingoes, domestic and feral dogs, feral cats and introduced red foxes. Wallabies are also hunted for meat and fur, and many are killed by cars because they feed near roads and towns. The banded hare-wallaby, once common across southern Australia, now survives only on two Western Australian islands free of introduced predators, as does the quokka. Captive breeding of rock-wallabies has had some success, with a small number released back into the wild.