Kangaroos and wallabies are marsupials that belong to a small group of animals called macropods. They are only found naturally in Australia and Papua New Guinea. The word macropod actually means 'big foot'. Kangaroos and wallabies are most active at night, dusk and dawn.
The kangaroo super-family consists of two family groups. Kangaroos, wallabies, pademelons and tree-kangaroos make up one family, while rat-kangaroos, bettongs and potoroos make up the other.
Kangaroos are Australia's best-known animals. Since they were first seen by European settlers - who were amazed at such strange animals - a lot has happened to these unique creatures. There are now more of some kangaroo species, generally the larger ones, than when the European settlers arrived. Other species are gone forever, made extinct by surroundings that were changed too much for them to survive. Many of less well known surviving species are also decreasing in number and may become extinct if we do not take some action.
Kangaroos, and their close relatives, vary greatly in size, ranging in weight from 500 grams to 90 kilograms. There are some 45 different types of kangaroo.
Kangaroos of all sizes have one thing in common - powerful back legs with long feet. They are distinguished from other animals by the way they hop on these strong back legs. Only a few other small mammals, such as hopping mice, do this.
Hopping uses slightly less energy than four-footed running, but this advantage is lost at low speed. To move slowly, kangaroos balance on their front paws and tail, and then swing their hind legs forward in a pendulum motion.
Kangaroos have adapted to the varied conditions across Australia in many ways. One of the most unusual, is the way females of some species can delay the progress of pregnancy. In this way the female is ready to give birth to a replacement for the young in her pouch if it dies early, or within a week of when it permanently leaves the pouch. This ability to delay births means that there can be up to 12 months between a mating and the birth of the young one resulting from that mating (when the normal gestation period is less than 35 days). It also means that the species can best respond to periods of drought and plenty.
Species which have this unusual ability normally mate again soon after the female gives birth. The tiny newly born kangaroo (less than 25 mm long) moves unaided into its mother's pouch and attaches itself to one of four teats. During the early stages of pouch life the young is permanently attached to the teat, but as it matures and begins to grow hair it also develops the ability to release and reattach itself to the teat.
In the late stages of pouch life, once it has a thin covering of fur, the young one begins to explore the outside world for increasing lengths of time until eventually it is old enough to be excluded permanently from the pouch. Complete weaning may take a number of months more after the young has permanently left the pouch. If the mother gives birth during this time, the newborn young will attach itself to a different teat to that being used by the older young. It is remarkable that when this happens the mother produces two different kinds of milk for the two different-aged young.
The Red Kangaroo is the largest living marsupial. Males can be over 6 feet tall and weigh up to 90 kilograms. It is able to go without drinking as long as green grass is available, and it adapts well to drought. Despite its name, the Red Kangaroo is sometimes a blue - grey colour, particularly the female.
The Eastern and Western Grey Kangaroos live where rainfall is greater than 250 millimetres a year, through eastern Australia and across the southern coast to south-west Western Australia. Populations vary considerably according to conditions, but the two species are very common.
This small Wallaby wanted to get into the car with me (and the food) at Cradle Mountain in Tasmania.
Also quite common are the smaller species known as Wallabies, these are found in any terrain and vary from common to endangered.
Tree-kangaroos are adapted to living in trees. They have stronger front limbs than other kangaroos, shorter hind legs, and feet with a rough-textured sole to allow for a better grip. Despite these features, they are awkward in trees. Most species are found in the dense forests of New Guinea. The two Australian species - Lumholtz's Tree-kangaroo and Bennett's Tree-kangaroo are found in small areas in the tropical rainforests of north Queensland. They feed on leaves and fruit.
Rock wallabies are a large group of quite different-looking species. As their name implies, they prefer rocky regions. They are found throughout Australia. Because they prefer rocky gorges, cliffs and boulder jumbles, populations may be confined to widely separated and small areas.
Pademelons are small wallabies that live in wet forest areas. The Tasmanian Pademelon is known for its fine fur. It was once hunted in great numbers, but remains abundant today. Pademelons prefer similar habitats to potoroos, but have a different diet - they eat juicy grasses and shrubs. All three species remain common.
Potoroos are mainly found in the wet forests and heathlands of east and south-east Australia. They feed in the open, but retreat to thick undergrowth for protection.
Bettongs are found in drier areas than those preferred by the potoroos. Like most small macropods found in arid areas, bettongs are active at night to avoid moisture loss during the heat of the day. The Burrowing Bettong does not drink. It gets the moisture it needs during the night from juicy sandhill plants. Only two species, the Tasmanian Bettong and the Rufous Bettong can be regarded as common. Even so, they are found over a smaller area than before, due mainly to clearing of their habitat for farms and feral animals like cats and foxes.