KANGAROO

A kangaroo is any of several large macropods (the marsupial family that also includes the wallabies, tree kangaroos, wallaroos, pademelons and the quokka: 45 species in all). The term kangaroo is sometimes used in a broader sense to refer to all members of the macropod family. Kangaroos are native to the continent of austrslis , while tree kangaroos are also found in New Guinea.

The word kangaroo is said to derive from the Guugu Yimidhirr (an Australian Aboriginal language) word gangurru, referring to the Grey Kangaroo (see photo to the right). The name was first recorded as kangaru in 1770 by Joseph Banks on James Cook's first voyage of exploration, when they were beached at the mouth of the Endeavour River in the harbour of modern Cooktown for almost 7 weeks repairing their ship which had been damaged on the Great Barrier Reef.

Kangaroo soon became adopted into standard English where it has come to mean any member of the family of kangaroos and wallabies. The belief that it means "I don't understand" or "I don't know" is a popular myth that is also applied to any number of other Aboriginal-sounding Australian words. Male kangaroos are called bucks, boomers or jacks; females are does, flyers, or jills and the young are joeys. The collective noun for kangaroos is a mob. Kangaroos are sometimes coloquially referred to as 'roos.

• The Red Kangaroo (Macropus rufus) is the largest surviving marsupial anywhere in the world. Fewer in numbers, the Red Kangaroos occupy the arid and semi-arid centre of the continent. A large male can be 2 metres (6 ft 6 in) tall and weigh 90 kg (200 lb).
• The Eastern Grey Kangaroo (Macropus giganteus) is less well-known than the red (outside of Australia), but the most often seen, as its range covers the fertile eastern part of the continent.
• The Western Grey Kangaroo (Macropus fuliginosus) is slightly smaller again at about 54 kg (119 lb) for a large male. It is found in the southern part of Western Australia, South Australia near the coast, and the Darling River basin.

In addition, there are over 41 smaller macropods that are closely related to the kangaroos:

• Tree kangaroos are arboreal relatives of the true kangaroo which are found in the dense rainforests of north-east and New Guinea. Several tree kangaroos are endangered, largely because of habitat destruction.
• are smaller, usually more thick-set, macropods.
• A wallaroo is a very large wallaby or a small kangaroo.
• Pademelons are small, forest living macropods of around 4 to 6 kg (9 to 13 lb).
• The Quokka is a small wallaby-like macropod of Western Australia.
• Rat kangaroo is a term loosely applied to any of several very small kangaroo-like marsupials, some from the family Macropodidae, some not.
• Kangaroo rats, in contrast, .

Physical Description

A male kangaroo's scrotum is lowered in warm weather to keep it away from the heat of the body

Kangaroos have large powerful hind legs, large feet designed for leaping, a long muscular tail for balance, and a small head.

Unlike that of many other mammals, kangaroos' scrotum is located far ahead of the penis, almost in the middle of the belly. In hot weather it can be seen lowered by the relaxed animal to keep the testes cool, and raised when moving about. (This body part can be found in souvenir shops as "lucky pouch"...)

Kangaroos are the only large animals to use hopping as a means of locomotion.

A young Eastern Grey Kangaroo in motion

The comfortable hopping speed for Red Kangaroos is about 20–25 km/h (13–16 mph), but they can hop as fast as 70 km/h (43 mph) over short distances.

This fast and energy-efficient method of travel has evolved less in response to the danger of predators, but more because of the need to regularly cover large distances in search of food and water.

The average life span of a kangaroo is around 9 years.

Diet

A mob of Forester ( Eastern Grey) Kangaroos grazing. The dominant one looks cautiously at the approaching photographer in Narawntapu National Park, Tasmania.

Kangaroos are large herbivores, feeding on grass and roots, and they chew cud. Their heads in fact look much like those of llamas. All species are nocturnal and crepuscular, usually spending the days idling quietly and the cool evenings, nights and mornings moving about and feeding, typically in groups called mobs. The life expectancy of a kangaroo is about 18 years.

Predators

Kangaroos have few natural predators. One of the major natural predators, the Thylacine, is now extinct. However, humans arrived in Australia at least 50,000 years ago and introduced the dingo about 5,000 years ago. The use of dingoes, and later hunting dogs by Europeans, to hunt kangaroos has resulted in most kangaroos having an enmity for dogs. The mere barking of a dog can set a full-grown male boomer into a wild frenzy. In extreme circumstances, one or more Wedge-tailed Eagles will attack and sometimes kill a kangaroo (even an adult Red), but only when no more suitably-sized food is available. Goannas and other carnivorous reptiles also pose a danger to the smaller kangaroo species when other food sources are lacking.

Along with dingoes and other canids, introduced species like foxes and feral cats also pose a threat to kangaroo populations, as they do most native populations. Kangaroos and wallabies are apt swimmers, and often flee into waterways if presented with the option. If pursued into the water, a large kangaroo may use its forepaws to hold the predator underwater to drown it. Another defensive tactics described by witnesses is catching the attacking dog with the forepaws and disemboweling it with the hind legs.

Social Life & Courtship

Red Kangaroos at Lone Pine Koala Sanctuary at Brisbane, Queensland,

The large macropods such as the red and grey kangaroos form highly social groups called mob, troop or court. A mob may have ten or more males and females. The dominant male (also called boomer) is based on his size and age. A boomer has temporary exclusive access to females in a mob for mating. A boomer may find himself wandering in and out of a mob - checking out the females and intimidating the other males who try to mate with the females within the mob.

Courtship behaviour in most species of kangaroos includes the male "checking" the female's cloacal area. The males are often rejected by the females for their smaller size, but in the case of a larger kangaroo, the female may instead simply move away. Often, when the female is being checked, it urinates. The male kangaroo will then make a practice of sniffing the urine multiple times until it is satisfied, then proceed to the mating cycle. Studies of Kangaroo reproduction conclude that this ritual is typical for a male kangaroo to check if the female kangaroo is receptive to the male.

The sexually aroused male follows the responsive female (she raises her tail). Tail scratching (a form of foreplay) can occur between the male and female. The arched tail is indicative that either one or both kangaroos are ready to mate. The male kangaroo may sometimes be found giving the female kangaroo a back rub before mating.