Home Life Trends Koala - Facts, Diet, Habitat, Characteristics

Koala - Facts, Diet, Habitat, Characteristics

Evolution and systematics

The koala household, Phascolarctidae, are believed to have diverged from their nearest marsupial family, the wombats, round 24 million years in the past (mya). At least six totally different members of the koala household developed. The earliest fossil report of a koala was a browser, Perikoala palankarinnica , some 15 mya. More not too long ago, a large koala, Phascolarctos stirtoni, was a 3rd as massive once more as our current day koala, however is believed to have died out together with different marsupial megafauna some 40,000 years in the past, at across the time that aboriginal hunter-gatherers colonized Australia. Only one species, Phascolarctos cinereus , survives at present. Phascolarctos is from the Greek phrases for “leather pouch” and “bear,” whereas cinereus means “ash-colored.”

There are three subspecies of koala, Phascolarctos c. victor, native to the state of Victoria; Phascolarctos c. cinereus , native to New South Wales; and Phascolarctos c. adustus, native to Queensland. Koalas within the north have shorter coats and are smaller than their southern cousins, and genetic research have confirmed vital variations between the 2 populations, in addition to suggesting that there could also be plenty of distinct subpopulations within the north. Southern populations seem extra homogenous, in all probability because of the quite a few translocation tasks which have taken place.

The taxonomy for the koala is Phascolarctos cinereus (Goldfuss, 1817), New South Wales, Australia.

Physical traits

The comical, interesting, “teddy bear” look of the koala has made it Australia’s iconic animal. Despite the deceptive standard title “koala bear,” koalas are usually not, in fact, associated to the omnivorous bear household, however are herbivorous marsupials. They are medium sized, with a head and physique size that may be as brief as 24 in (60 cm), or so long as 33 in (85 cm), however is normally within the vary 28-31 in (72-78 cm). Body weight may also range significantly, from as little as 8.Eight lb (four kg) for a northern feminine, to as a lot as 33 lb (15 kg) for a southern male, however the regular vary is 11-26 lb (5.0-11.Eight kg). Males are up to 50% bigger than females, and there's a vital dimension difference between koalas in Queensland, the place males common 14.Three lb (6.5 kg) and people additional south, the place males common 26 lb (11.Eight kg).

The koala has a compact physique with a broad head, massive nostril, and small eyes. The ears are massive and rounded with white edges. Koalas have solely a vestigial tail, which is of no help in climbing, however they've lengthy, sturdy limbs, with massive paws and sharp claws that are properly tailored to grip clean-barked eucalyts. Fore and hind ft have 5 digits, all with sharp, recurved claws, apart from the primary digit of the hind foot, which is brief and broad. The first and second digits of the forefeet are opposable to the opposite three, permitting the animal to grip smaller branches and climb into the outer cover looking for contemporary leaves. The second and third toes of the hind ft are fused, with a double claw.

Koalas don't use dens nor shelters, so their fur is essential for insulation. Southern koalas have dense, woolly coats, with thicker, longer fur on the again than the stomach. Koalas dwelling additional north in hotter subtropical and tropical areas have shorter coats (additionally lighter in colour), generally showing nearly bare. The colour and sample of coats varies significantly between people and with age, from grey to tawny, with white on the chin, chest, and forelimbs and whitish dappling on the rump. Males have a big chest gland that's used for scent marking timber. Females have a marsupial pouch opening to the rear and containing two teats.


Australia’s koala inhabitants is present in a broad coastal swathe down the jap seaboard, from the Atherton tablelands in north Queensland to southwestern Victoria. Although that is an space of a number of hundred thousand sq. miles (kilometers), deforestation, habitat degradation, and historic persecution imply particular person populations inside this vary are fragmented and sometimes remoted.

Historically, the geographical vary of koala populations was broadly related to at present, however prolonged into South Australia and southern components of Western Australia. Land clearance and looking brought about populations inside this vary to contract, and in lots of instances turn into extinct. However, intensive koala administration and reintroduction packages have reversed this decline in lots of locations, notably within the south, and koalas are actually domestically widespread the place appropriate habitat survives. Numerous localized populations have been re-established in South Australia and Western Australia.


Koalas feed nearly solely on eucalyptus leaves, so their habitat is invariably eucalypt forest and woodland. However, they'll tolerate a surprisingly various vary of environmental and weather conditions. In the tropical north habitat is commonly dense thicket, with excessive year-spherical temperatures and robust seasonal rainfall. Rainfall can also be excessive within the temperate mountain rainforests of the south, however winters might be a lot colder. This fertile habitat can assist populations as excessive as three animals per acre (0.four ha), a stark distinction to the semi-arid open woodland habitat of the west, the place a single animal could require 250 acres (100 hectares) to survive.

In temperatures above 77°F (25°C) koalas use evaporative cooling of their airways to regulate temperature, by respiratory quickly, however cut back water loss by lowering the quantity of water of their urine. In chilly temperatures koalas, like people, preserve warmth by decreasing blood move to extremities, and have additionally been seen to shiver, a method of manufacturing warmth by fast muscle contraction.


Koalas are primarily solitary animals, with little or no social interplay apart from in the course of the breeding season. Adults occupy fastened house ranges. Range dimension relies on the productiveness of the atmosphere, however might be as little as 2.5 acres (1 ha) for a male in a fertile habitat, and half that for a feminine. Within this vary an animal could reside a lot of its life in solely a dozen favored timber. A dominant grownup male’s vary will overlap the vary of up to 9 females and plenty of subordinate and subadult males.

Within the realm of a secure social group particular person koalas will “own” plenty of food timber and “home range trees” marking the sting of their vary. A koala trespassing into an “owned” tree could also be aggressively attacked by the resident, however scent markings and scratchings normally warn animals {that a} tree is underneath possession. Other timber the place ranges overlap shall be shared, and it's right here that restricted social interplay takes place.

Koalas are largely nocturnal, feeding and transferring after nightfall. They hardly ever depart the safety of the timber, descending to the bottom solely to transfer to one other food tree, or to eat soil, which aids digestion. Koalas stroll on 4 legs, run with a bounding gait, and may swim if obligatory.

As one adaptation to their low-power eucalyptus leaf food plan, koalas sleep up to 20 hours a day, normally wedged comfortably into the fork of a tree. Even when awake, koalas spend a lot time resting, and feeding occupies solely 10% of their day.

Activity livens up in the summertime breeding season, when dominant males will try to defend their territory for breeding rights with resident females. At this time of year males use their chest gland to scentmark tree trunks and may typically be heard bellowing, apparently to warn off rival males and appeal to females. This deep, grunting bellow typically provokes responses from different males within the space. At evening males transfer round extra, preventing with any competing grownup males that they encounter, or mating with estrous females.

Koalas have a variety of different sounds for communication. Mothers and infants make gentle clicking, squeaking sounds, and delicate murmuring, or will grunt if irritated. All koalas are able to a distressing, excessive-pitched cry like a screaming child when afraid.

Feeding ecology and food plan

Australia has some 650 species of eucalypt, however koalas are picky eaters, and feed on solely round 30 species, with only a handful, together with river purple gum, grey gum and manna gum, most popular. They have often been identified to eat noneucalypt leaves, together with acacia, mistletoe and field. Koalas eat about 1.3 to 1.Eight lb (600 to 800 g) of leaves a day.

Koalas attain their food by climbing excessive up clean, vertical eucalypt trunks, gripping with their sharp foreclaws and utilizing their highly effective entrance legs to pull themselves up, whereas bringing their hind legs up to their entrance. Although they often transfer slowly and laboriously to preserve power, they're able to shocking agility and may leap 6 ft (2 m) from trunk to trunk.

Eucalyptus leaves are low in vitamins, comprise a big proportion of indigestible cellulose and lignin, and are filled with poisonous chemical substances. Koalas have developed plenty of methods to address this poor food plan. They keep away from essentially the most poisonous species, and range their alternative of food tree all year long as toxin ranges range seasonally in some species. The koala’s liver is able to detoxifying and excreting some toxic compounds from these species they do eat. Koalas have massive cheek pouches, to deal with massive quantities of poor high quality forage, and properly-developed tooth, which embrace a single premolar and 4 molars in every jaw, which grind the fibrous leaves to a fantastic paste. This is then digested by microbial fermentation within the animal’s unusually lengthy cecum (a blind sac within the digestive tract, between the junction of the small and enormous intestines). A koala’s cecum might be greater than 75 in (2m) lengthy.

The low power yield of the koala’s food plan explains their sluggish, sedentary life-style. However, it's a fantasy that koalas are drugged by the toxic compounds in eucalyptus leaves. What is true is that koala have one of many smallest brains of all marsupials relative to physique dimension—solely 0.2% of physique weight— and this has been defined as an extra response to food plan, because the mind is without doubt one of the most power-consuming of the physique’s organs.

Koalas acquire most of their water from leaves, however often drink at streams, and in captivity typically select to drink contemporary water.

Reproductive biology

Koalas are polygynous. During the summer time breeding season a dominant male will try to mate with any estrous females he encounters in his vary. Copulation lasts solely a few minutes, with the male mounting the feminine from behind and holding her towards a department. Females are ####ually mature at two years outdated, however usually don't begin to breed till they're older—full bodily maturity is reached at about 4 years outdated in females, 5 years outdated in males.

Females have an estrous cycle of about 30 days, and normally breed as soon as yearly, between November and March. Gestation lasts about 35 days earlier than a single younger (very hardly ever twins) is born, weighing lower than 0.02 oz (0.5g) and measuring about 2 cm lengthy. The tiny new child koala crawls into the mom’s massive pouch and attaches itself to one of many two teats. By 13 weeks the younger joey may have grown to about 2 oz (50 g), and by 22 weeks its eyes open and it begins to poke its head out of the pouch for the primary time. Joeys have a pouch life of 5 to seven months, after which they spend most of their day trip of the pouch, clinging to the mom’s stomach and later sitting on their again. Joeys are weaned at six to 12 months, however in direction of the tip of their pouch life additionally feed repeatedly on gentle, partially-digested leaf materials handed via the mom’s digestive tract. This “pap,” which incorporates a excessive focus of microorganisms, is believed to be essential in introfelling and urbanization, and human disturbance, notably via fireplace, as the key threats.

Unfortunately, koalas inhabit exactly these jap seaboard areas of Australia which can be seeing most fast urbanization and agricultural growth. In the previous 200 years an estimated one-third of Australia’s eucalyptus forest has disappeared, and in semi-arid components of Queensland, 1000's of acres of woodland are nonetheless being cleared for agricultural use yearly. Urbanization and vacationer growth alongside the coastal strip is additional fragmenting eucalyptus woodlands. Bush fires attributable to negligence or arson account for 1000's of deaths annually, whereas an estimated 10,000 koalas are killed in highway accidents. Koalas put up no resistance to assaults from home canine, and don't cope properly with stress, having abnormally small adrenal glands. There can also be proof that inbreeding in remoted, fragmentary populations is main to bodily abnormalities.

Despite all these pressures, there are literally places the place koala populations have thrived to such an extent that they're inflicting environmental harm. Koalas have been translocated to plenty of islands the place they weren't discovered naturally as way back because the 1870s. Populations on Phillip and French Islands in Victoria, and Kangaroo Island in South Australia have grown so massive that the unpalatable prospect of culling has been proposed. Thousands of animals have been relocated again to the mainland, inflicting related overcrowding Challenges in some places, and contraception is being investigated as a extra publicly acceptable different to culling.

One doable rationalization for these overpopulation Challenges is that the island populations are freed from chlamydia, a illness that's now thought to have been endemic in koalas for a few years, and will have acted as a pure inhabitants management, remaining benign when situations have been good, however killing off weaker animals throughout nerve-racking occasions akin to when habitat is diminished.

Some koala conservation work, together with buy of land for protected reserves, is being carried out by state authorities, however a lot koala conservation and analysis is within the arms of charities and privately-run welfare organizations. The koala’s cute and cuddly enchantment helps elevate funding for such non-authorities organizations.

One Challenge in planning conservation administration is the issue in acquiring correct inhabitants figures. The Australian Koala Foundation suggests numbers have dropped from 400,000 within the mid-1980s to between 40,000 and 80,000 at present, however this estimate can solely be an informed bet. The Foundation is compiling a nationwide atlas of surviving koala habitats, which can present a device to foyer for habitat conservation.

Significance to people

The title koala is believed to have originated from Aboriginal dialect names for the animal, which embrace cullewine, koolewong, colo, colah, and koolah. One steered translation for these Aboriginal names is “no water,” referring to the koala’s skill to largely subsist on moisture from leaves.

Australia’s Aboriginal people have lengthy hunted koalas for food—they make a sluggish-transferring goal simple to hit with a boomerang. But conventional Dreamtime tales educate Aborigines that in the event that they fail to respect the animal they are going to be visited by a horrible drought. Tradition dictates that whereas koalas could also be eaten, they need to not be skinned nor their bones damaged.

No such respect was accorded by early European settlers who shot koalas for “sport” and later for fur. Today koalas have a unique, however equally essential business significance, as animal ambassadors for the vacationer commerce. So essential is the koala as a vacationer draw card, notably to the essential Japanese market, that strikes by state governments to ban “koala cuddling” on the grounds that it's nerve-racking for the animals, have been opposed (unsuccessfully) by vacationer authorities.

Where populations are wholesome wild koalas are simple to observe, however most vacationers see koalas in zoos and animal sanctuaries, the place petting, if not cuddling, is allowed. The Australian federal authorities strictly controls exports of reside koalas, and this, mixed with the Challenges of satisfying the koala’s very particular dietary necessities, imply there are solely a handful of zoos outside Australia, within the United States, Japan, Germany, and Taiwan, the place koalas are exhibited.