Kangaroo

? Kangaroos
Eastern Grey Kangaroo
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Subclass: Marsupialia Order: Diprotodontia Suborder: Phalangerida Family: Macropodidae Genus: Macropus Shaw, 1790
Species
Macropus rufus Macropus giganteus Macropus fuliginosus

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 Australia, 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.

Overview

There are three species:

• 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 Australia and New Guinea. Several tree kangaroos are endangered, largely because of habitat destruction.
• Wallabies 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, are rodents.

Physical Description

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.

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

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

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.

Adaptations

Kangaroos have developed a number of adaptations to a dry, infertile continent and a highly variable climate. As with all marsupials, the young are born at a very early stage of development after a gestation of 31-36 days. At this stage, only the forelimbs are somewhat developed, to allow the newborn to climb to the pouch and attach to a teat. In comparison, a human embryo at a similar stage of development would be about 7 weeks old, and premature babies born at less than 23 weeks are usually not mature enough to survive. The joey will usually stay in the pouch for about 9 months or (for the Western Grey) 180 to 320 days, before starting to leave the pouch for small periods of time. It is usually fed by its mother until the age of 18 months.

A female kangaroo is usually pregnant in permanence, except on the day she gives birth; however, she has the ability to freeze the development of an embryo until the previous joey is able to leave the pouch. The composition of the milk produced by the mother varies according to the needs of the joey. In addition, she is able to simultaneously produce two different kinds of milk for the newborn and the older joey who still lives in the pouch.

Kangaroos and wallabies have a unique ability to store elastic strain energy in the tendons of their large hind legs. As a consequence, most of the energy required for each hop is provided by the spring action of the tendons rather than by muscular effort. There is also a linkage between the hopping action and breathing: as the feet leave the ground, air is expelled from the lungs; bringing the feet forward ready for landing fills the lungs again, providing further energy efficiency. Studies of kangaroos and wallabies have demonstrated that, beyond the minimum energy expenditure required to hop at all, increased speed requires very little extra effort (much less than the same speed increase in, say, a horse, a dog, or a human), and also that little extra energy is required to carry extra weight. For kangaroos, the key benefit of hopping is not speed to escape predators — the top speed of a kangaroo is no higher than that of a similarly-sized quadruped, and the Australian native predators are in any case less fearsome than those of other continents — the benefit is economy: in an infertile continent with very variable weather patterns, the ability of a kangaroo to travel long distances at moderately high speed in search of fresh pastures is crucial.

A sequencing project of the Kangaroo genome was started in 2004 as a collaboration between Australia (mainly funded by the State of Victoria) and the NIH in the USA. The genome of a marsupial such as the kangaroo is of great interest to scientists studying comparative genomics because marsupials are at the right "distance" from humans: mice are too close and haven't developed many different functions, while birds are already too far away. The dairy industry has also expressed some interest in this project.

Kangaroo blindness

The eye disease is rare but not new among kangaroos. The first official report of kangaroo blindness took place in central New South Wales in 1994. The following year, reports of blind kangaroos appeared in the southern states of Victoria (Australia) and south Australia. By 1996, the disease had spread "across the desert to western Australia". Australians were concerned that the disease could spread to other livestock and to humans. Researchers at the Australian Animal Health Laboratories or (AAHL) in Geelong, Australia, detected a virus called the Wallal virus in two species of midges or sand flies, which they believe were the carriers. Veterinarians also discovered by screening the kangaroo population, that less than three percent of kangaroos exposed to the virus developed blindness. [1]

Kangaroos and humans

Unlike many of the smaller macropod species, kangaroos have fared well since European settlement. European settlers cut down forests to create vast grasslands for sheep and cattle grazing, added stock watering points in arid areas, and have substantially reduced the number of dingos. There are more, probably many more, kangaroos in Australia now than were present in 1788.

Along with the Koala, the kangaroo is regarded as the signature animal of Australia. The kangaroo and the emu appear on the Australian coat of arms. Kangaroos are often represented in toys and souvenirs. The kangaroo is part of the logo of Qantas, the largest Australian airline. The Australian national rugby league team is nicknamed the Kangaroos.

Eating

The kangaroo has been historically a source of food for indigenous Australians.

Kangaroo is a red meat with a strong flavour, low in fat compared with other red meats, and rich in iron giving it a substancially darker appearance. It is best cooked a little rare. Preparation is essential, otherwise the meat can be quite tough in texture.

Kangaroo meat is high in protein, low in fat (about 2%), and about 40% of that fat is long-chain polyunsaturated fatty acid - considered healthy. Kangaroo meat is stronger in flavour than the meat from other animals (since it is game meat), is very tender, and will keep for longer than other types of meat due to the low fat content, but it can easily become dry if cooked improperly due to the low fat content.

Whilst kangaroo was once limited in availability, consumption in Australia is becoming more widespread. Most supermarkets now stock various cuts of kangaroo including fillets, steaks and 'kanga bangas' (kangaroo sausages). There has been recent discussion from the kangaroo meat industry about attempting to introduce different nomenclature for kangaroo meat, similar to the reference to pig meat as ham and pork. In 2005, Food Companion International magazine ran a competition to find such a name, with the winning entry being australus, but this has not been officially adopted by the industry.

Kangaroo meat has been quite successful on the European market, particularly in Germany. It is also processed into dog food. Culling is closely monitored by the RSPCA and state authorities. Kangaroo farming is a substantially more environmentally friendly meat industry than present sheep or cattle farming: kangaroos require less feed than placental stock, are well-adapted to drought, do not destroy the root systems of native grasses in the way that sheep do, and have much less impact on Australia's fragile topsoils. However as of 2004, the traditional regulatory restrictions on the sale of kangaroo meat in the Australian domestic market make kangaroo farming economically unattractive. Nevertheless, the industry is worth around A$200 million annually.

Kangaroo culling

Today, in some areas, kangaroos are culled by licenced professional hunters. Both the meat and the hides are sold.

Although most species of macropod are protected from hunting by law, a small number of the large-sized species which exist in high numbers can be hunted by commercial hunters. [2] This policy has been criticised by some wildlife activists. [3]

Kangaroo meat, entirely from professional culling operations where the animals are head or heart-shot in the wild. Animal activists have made claims of hunters killing the joey along with its mother. Roo meat appears in Australian supermarkets in the form of kangaroo steaks, minced meat, and sausages.

Kangaroo culling arouses some controversy as some object to the shooting of an animal that appears on the national emblem.

There are probably around 50 million kangaroos in Australia [4]. These numbers have increased significantly, from 21 million, since kangaroo meat operations began.

In 2002 the number of kangaroos allowed to be shot by commercial hunters was increased from 5.5 million to 7 million per year. [5] While animal rights activists protested the move, Australian farmers said that there was a "plague" of kangaroos after a huge increase in their numbers. [6] In July 2003 animal activists protested a planned cull of 6,500 kangaroos near the Puckapunyal army base. [7] In July 2004 the ACT government began a program of shooting kangaroos around the Googong Dam near Canberra while animal activists, many who had come from overseas, protested against it. [8] It was ordered because of fears of the dam becoming contaminated after a large downpour of rain if the kangaroos ate away all the grass.

Threat to humans

Kangaroos are shy and retiring by nature, and in normal circumstances present no threat to humans. Male kangaroos often "box" amongst each other, playfully, for dominance, or in competition for mates. The dexterity of their forepaws is utilized in both punching and grappling with the foe, but the real danger lies in a serious kick with the hindleg. The sharpened toenails can disembowel an opponent, and this is the fate of many dogs that wrestle with a boomer. Boxing Kangaroos have been portrayed in popular culture, especially Bugs Bunny cartoons.

There are very few records of kangaroos attacking humans without provocation, however several such unprovoked attacks in 2004 spurred fears of a rabies-like disease possibly affecting the marsupials. The only reliably documented case of a fatality from a kangaroo attack was New South Wales, in 1936. A hunter was killed when he tried to rescue his two dogs from a heated fray. Other suggested causes for erratic and dangerous kangaroo behaviour have been extreme thirst and hunger.

Kangaroo traffic sign

The "Kangaroo crossing" sign is to warn motorists to drive carefully and to watch out for kangaroos, because of the possibility of the presence of kangaroos in the area. The signs are not placed randomly; they are placed based on the frequency of reported collisions. A collision between a car and kangaroo is capable of killing the kangaroo and damaging the car.

Kangaroos blinded by headlights or startled by engine noise have been known to leap in front of cars. The local saying describes their road-crossing habit as "look right, look left, and cross anyway". Since kangaroos in mid-bound can reach speeds of ~50 km/h(31 mph) and are relatively heavy, the damage to vehicles can be severe. It will also kill the kangaroo. Small vehicles may be destroyed, while larger vehicles may potentially suffer engine damage. If thrown through the windscreen, the risk of harm to vehicle occupants is greatly increased. For this reason, vehicles that frequent isolated highways where roadside assistance may be scarce are often fitted with " roo bars" to protect from the damage caused by such accidents. Hood-mounted devices, designed to scare the wildlife off the road with ultrasound and other effects, are being devised and marketed.

Another horrifying responsibility of a motorist is to finish off the wounded animal. A broken hind leg, for example, spells prolonged and painful death for the creature. Shooting or a swift smashing of the head by a hammer or a rock is required by the humane custom.

A dead animal should never be left on the road, otherwise a scavenging carrion-eater (such as Tasmanian Devil or a bird) eating it may be killed by another car. It is advocated that the corpse be moved as far away from the road as practical.

If a female marsupial is a victim of a collision, animal welfare groups ask that her pouch be checked for an infant joey, which may often survive the accident. In this case the joey should be taken to a wildlife sanctuary or veterinary surgeon so that the joey can be cared for and hopefully saved.

Some people would nurse the little joey themselves. The rule-of-thumb says that if the joey is already covered with fur at the time of the accident, it stands a good chance of growing up properly. Lactose-free milk is required, otherwise the animal may develop blindness. They hop readily into a cloth bag when it is lowered in front of them approximately to the height where the mother's pouch would be. The joey's instinct is to "cuddle up", which endears them to their keepers, but after around six months the grown animal should be released into the wild after several preparatory visits there.

Famous Kangaroos

• Skippy the Bush Kangaroo - the kangaroo star of an Australian television series

• Lulu, a pet Kangaroo who saved a farmer's life. Winner of the RSPCA National Animal Valor Award on May 19, 2004. [9] [10] [11]

• Matilda [12], the 13-metre mechanical mascot for the 1982 Commonwealth Games held in Brisbane, Queensland, Australia

• The Boxing Kangaroo, mascot for the Australia II team in the 1983 Americas Cup.

• Kidding Kangaroo in the Sweet Pickles book series by Ruth Lerner Perle, Jacquelyn Reinach, and Richard Hefter

• Kangaroo Jack - the title of an American film

Pre-Historic Kangaroos

• Procoptodon
• SthenurusStrong Tail [13]
• Propleopus, carnivorous kangaroo during the pliocene and pleistocene periods (e.g. giant rat kangaroo)
• Simosthenurus, leaf-eating (browsing) kangaroos