Kangaroo
) 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.
The average
life expectancy of a kangaroo is about 9-18 years, with some living until they are about 28.
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 mobs.
Predators
Kangaroos have few natural
predators. The
Thylacine, considered by palaeontologists to have once been a major natural predator of the kangaroo, is now
extinct. However, with the arrival of humans in Australia at least 50,000 years ago and introduction of the
dingo about 5,000 years ago, kangaroos have had to adapt to introduced predators. The mere barking of a dog can set a full-grown male boomer into a wild frenzy.
Wedge-tailed Eagles are opportunistic predators who may prey upon juvenile kangaroos and will attack and sometimes kill a kangaroo (even an adult Red), but only when no more suitably-sized food is available. Wedge-tailed Eagles and other raptors usually eat already deceased kangaroos and can be found feeding on road-kill.
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 populations of native animals. 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
tactic described by witnesses is catching the attacking dog with the forepaws and
disemboweling it with the hind legs.
Social life and courtship
A mob may have ten or more males and females. The dominant male (called a 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 behavior in most species of kangaroos includes the male "checking" the female's
cloaca. 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
|
Newborn joey sucking on a teat in the pouch |
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.
|
Kangaroo statue on Grassy Hill at Cooktown, a monument to the first time that European settlers (Captain James Cook) saw the kangaroo when landing on the shores of Cooktown in 1770. |
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 large, stretchy tendons in their hind legs which have evolved for leaping. They store elastic strain energy in the
tendons of their large hind legs, providing most of the energy required for each hop by the spring action of the tendons rather than by muscular effort. This is true in all animal species which have muscles connected to their skeleton through elastic (spring like) elements, like tendons, but the effect is more pronounced in kangaroos.
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]
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, as is the
North Melbourne Football Club in
Australian rules football.
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.
For details on Kangaroo culling, and their use for meat, fur and leather, see Kangaroo culling and produce. |
A kangaroo-crossing sign in mainland Australia. |
|
This sign in Tasmania is even more explicit. |
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 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. 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, and, as already mentioned, 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 now-grown young wallaby, whose mother died in a collision with a car, is brought into Kakadu National Park in preparation for being permanently released. |
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.
The kangaroo, like the
koala,
emu, &
echidna, is one of the national animals of Australia.
for the
1982 Commonwealth Games held in
Brisbane,
Queensland,
Australia]]
|
The reverse side of the Australian pre-decimal half penny coin features a kangaroo in "flight" |
*
Skippy the Bush Kangaroo - the kangaroo star of an Australian television series
*
Lulu, a pet Kangaroo who saved a farmer's life. Lulu was the winner of the
RSPCA National Animal Valor Award on May 19, 2004. [
2] , [
3] , [
4]
*
Matilda, the
mascot at the
1982 Commonwealth Games held in
Brisbane,
Queensland,
Australia, was represented by both a
cartoon kangaroo and a 13-metre high (42 feet 8 inches)
mechanical kangaroo (which
winked at the spectators during the opening and closing ceremonies). The 'medal', which was worn by both the cartoon and mechanical versions of
Matilda, features the
1982 Commonwealth Games logo — a
stylized representation of a kangaroo in "flight" – similar to the
pose of the kangaroo featured on the Australian pre-decimal
half penny coin (shown at right).
* The Kangaroo was also featured on the Australian pre-decimal
penny coin.
* The five Kangaroos are featured on the Australian
One Dollar coin.
* The Kangaroo and
Emu are standard bearers on the
Australian Coat-of-Arms * The Kangaroo is the logo of Australia's national airliner
Qantas.
* The
Boxing Kangaroo, mascot for the
Australia II team in the 1983
America's Cup. There is also a green and gold "Sporting Kangaroo", which is a
Cricket version of the Boxing Kangaroo flag, featuring a Kangaroo batsman, with cricket bat and batting gloves.
* Several national representative sports teams have nicknames derived in one way or another from the kangaroo:
**The
Australia national football (soccer) team (men's) is nicknamed the
Socceroos. Similarly, the Australia men's
Olympic team in the same sport is nicknamed
Olyroos.
**The national women's
field hockey team is known as the
Hockeyroos.
**The national men's
ice hockey team is known as the
Mighty Roos.
**One of the common terms for a grown male kangaroo,
boomer, provides the standard nickname for the
Australia men's national basketball team.
*
Kidding Kangaroo in the
Sweet Pickles book series by Ruth Lerner Perle,
Jacquelyn Reinach, and Richard Hefter
*
Kasey Kangaroo is the mascot for the
University of Missouriâ€"Kansas City*
Zippy the kangaroo is the mascot for
The University of Akron*
Lizzie (a purple and white kangaroo) is the mascot of
Lake Washington High School in
Kirkland, Washington*
Kangaroo Jack - the title of an American film
*
Embryonic diapause*
Kangaroo culling and produce*
Kangaroo court (mock justice)
*Dawson, Terence J. 1995.
Kangaroos: Biology of the Largest Marsupials. Cornell University Press, Ithica, New York. Second printing: 1998. ISBN 0-8014-8262-3.
*Flannery, Timothy Fridtjof, et al. 1996.
Tree Kangaroos: A Curious Natural History. Reed Books, Melbourne. ISBN 0-7301-0492-3
*Underhill D. 1993.
Australia's Dangerous Creatures, Reader's Digest, Sydney, New South Wales, ISBN 0-86438-018-6
*Weldon, Kevin. 1985.
The Kangaroo. Weldons Pty. Ltd., Sydney. ISBN 0-949708-22-4
*
The Kangaroo Genome Project at
Australian National University*
Interesting facts on kangaroos*
Courtship and Mating*
prehistoric mammals
