Kangaroo
is the given name to any of several large macropods (the family of marsupials
that includes the tree kangaroos, wallabies, wallaroos, pademelons and
the quokka) although the term kangaroo is sometimes used (incorrectly) to
refer to the whole of the macropod family. The word macropod means large foot.
Kangaroos are native to Australia, while tree kangaroos are also found
in New Guinea.
The word kangaroo derives from an Australian Aboriginal word gangurru,
referring to the Grey Kangaroo, and was first recorded in 1770 by Joseph Banks.
Male kangaroos are generally called bucks, although the terms boomers or jacks
are also used; females are usually called does, but flyers,or jills
can also be used. The young are known as joeys. A group of kangaroos is a
mob and kangaroo is normally abbreviated to 'roos.
1.
The Red Kangaroo (Macropus rufus) is
the largest marsupial with proportionately the longest hindlegs.It has short,
reddish fur (pale buff underneath), large box shaped face and can stand two
metres tall and weigh 85Kg. It inhabits all of the Australian states and is
widespread and common in arid and semi-arid areas. It is absent from all of
the eastern and northern coastal areas.The abundance of bore water for stock
and the availability of farm crops has lead to population expansion in rural
areas.
2. The Eastern Grey Kangaroo (Macropus
giganteus)
is smaller than the Red (up to 66Kg) and is a dull grey-brown (whitish underneath).
It is found throughout eastern Australia, including parts of Tasmania (where
it is called the forester kangaroo), and generally lives in open forest and
woodland, venturing out onto pasture at dusk. Found in huge numbers.
3.
The Western Grey Kangaroo (Macropus fuliginosus)
is the smallest of the three at a maximum height of one metre and weight of
54Kg. Darker brown above with dark muzzle. Found across southern Australia.
There are another 42 species of macropod found in Australia, plus a further
10 species of pottoroo and bettong, animals that are closely related to the
macropods. Information on this page is generally restricted o the three largest
kangaroo species, shown above.
Physical
description.
The most notable feature of the macropods are of course the long back feet
(from where the term macropod originates) and strong back limbs, both designed
for leaping.
They all have the ability to hop (the only large animals to do so for locomotion)
but will use the forepaws when moving about slowly. No kangaroos can walk
backwards (the kangaroo and the emu were chosen for the Australian coat of
arms because neither walks backwards, thus representing progress).
They have a strong tail which is used as a counterbalance when hopping and
as a fifth 'leg' when moving slowly (see adaptations, below).
They are marsupials and consequently have a (upwards opening) pouch for young
.
The female of most species have the ability to be almost constantly pregnant
(utilizing embryonic diapause) and can lactate from first pregnancy until
death (see adaptations, below).
A male kangaroo's penis is located in front of the scrotum and the scrotum
itself is lowered in hot weather in order to stop the testes from over-heating.
The scrotum is raised when the kangaroo moves around.
All kangaroos have the ability to move at surprisingly high speeds (Reds can
cruise at 30mph) for large distances. This is needed because of the large
area that often needs to be covered in search of food and water.
The average life span of a kangaroo is around 16 years.
Diet
Kangaroos are herbivores. The family eat a variety of plant and fungi matter.
They are crepuscular and nocturnal.
Predators
Adult large kangaroos have no natural predators. At one time the thylacine
hunted kangaroos but this animal is now extinct. Smaller kangaroos (including
juvenile large kangaroos) are sometimes taken by larger eagles, dingoes and
by larger monitor lizards. Non-natural predators of kangaroos include dogs
and, for the smaller macropods, cats and foxes. Of course man remains the
most successful hunter of kangaroos.
Kangaroos have developed a strong enmity towards dogs.
Kangaroos are far from defenceless against predators. Using their tail for
balance they will rock backwards and deliver a powerful kick using both hind
legs, something which has been known to disembowel many a dog. They are also
able swimmers and will sometimes engage a predator in the water, using it's
forepaws to hold the assailant under water until drowning occurs.
Adaptations
Kangaroos existed in Australia long before the continent was as dry as it
is today and changes to their physiology in order to cope with these changes
can be seen. Like all marsupials, the joey is born very early compared with
placentals. This places the mother under far less risk since there is no need
to carry the infant to full term and biologically there is no need to develop
a complex placenta.
Gestation for the larger kangaroos is 31-35 days. After this time the joey
(the size of a jelly bean) crawls through its mothers' fur and into the pouch,
whereupon it attaches itself to one of the two teats. This teat then expands
and thus prevents the joey from becoming dislodged. It will normally stay
in the pouch for the first nine months before venturing out for small periods
of time and will stay with the mother for 18 months.
A female kangaroo is usually pregnant for all but one day of the year (that
being the day she gives birth); however, she has the ability to arrest the
development of an embryo until the previous joey has left the pouch. She also
has the ability to vary the composition of the milk she produces to meet the
differing needs of her joey. She can also produce two different kinds of milk
for the newborn and the older joey.
Kangaroos have an incredibly efficient hopping motion. They are unique in
their ability to store elastic strain energy in the tendons of their large
hind legs and so 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 link between their breathing and their hopping. As the feet leave the ground
air is expelled from the lungs automatically and the lungs are re-inflated
by the forward movement of the legs, thereby adding further efficiency. Once
hopping has started a kangaroo uses very little energy to continue motion
and can therefore travel great distances with minimum effort. This is necessary
in a land where water and food are variable.
Kangaroos
and humans
The large kangaroos (in stark contrast to the smaller macropods) have fared
well since the arrival of European settlers. The huge increase in grazing
land, made possible by the sinking of wells and the construction of dams,
has lead to a massive increase in the food available to kangaroos, and most
agree that the populations have increased substantially. The population of
the Eastern, Western and Red kangaroos combined is between 15 and 50 millions,
varying with droughts. This high number has inevitably led to conflict with
farmers who see kangaroos as a "pest" in "plague" proportions,
who damage crops and fences.
Today, in some areas, kangaroos are culled by licenced professional hunters.
Both the meat and the hides are sold. There is an official quota for each
year which is based on 10-12 % of the population. This is generally viewed
as sustainable but has been criticized by some wildlife activists. In 2002
the number of kangaroos allowed to be shot by commercial hunters was increased
from 5.5 million to 7 million per year.
Kangaroo meat is available in Australian supermarkets in much the same way
as beef. However, most of the meat is sold to the pet food industry.
Main sources for this information:
Wikipedia
The Australian Government Department of the Environment and Heritage
The National Wildlife Foundation
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