[Animals] Koala Facts Enviroment & Behavior

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Habitat and distribution
Koalas live over a range of open forest and woodland communities but ultimately their habitat is defined by the presence of a select group of food trees. Koalas are found in higher densities where food trees are growing on more fertile soils and along watercourses. They do, however, remain in areas where their habitat has been partially cleared and in urban areas.

The distribution of koalas covers much of Queensland, New South Wales, Victoria and a small area in South Australia. Over the past 200 years, their distribution does not appear to have reduced, however, individual koala po[CENSORED]tions have declined. Local extinctions have occurred due to clearing and fragmentation of eucalypt woodlands and forests for agriculture and human settlement. Fossil records indicate that many years ago, the koala inhabited parts of Western Australia and the Northern Territory. There are no fossil records of koalas ever living in Tasmania.

In Queensland, the greatest concentration of koalas is in South East Queensland where they now compete for space with a rapidly growing human po[CENSORED]tion.
Description
Koalas are well-known for their large round head, big furry ears and big black nose. Their fur is usually grey-brown in colour with white fur on the chest, inner arms, ears and bottom. They have no fur on their nose or the palms of their paws. Koalas have particularly hard bottoms, which is similar to their closest relative, the wombat. For the koala, this feature enables them to wedge comfortably in tree forks for long periods of time, whereas the wombat uses its hard bottom as a defence mechanism.

Koalas have poor vision and rely heavily on their other senses. They have excellent hearing which helps them detect predators and other koalas. They have an acute sense of smell which also helps them detect other koalas and their favourite food trees. The male uses a scent gland on his chest to mark trees and attract females, by rubbing his chest up and down the trunk. The gland oozes a clear, oily, strong musky smelling liquid.
Diet
Koalas eat a variety of eucalypt leaves and a few other related tree species, including lophostemon, melaleuca and corymbia species (such as brush box, paperbark and bloodwood trees). They consume around 500 grams of leaves each day, (approximately the size of a small lettuce) and obtain most of their water requirements from the leaves, which can contain up to 50% water. This removes the need for a koala to climb down a tree for a drink of water, except during very hot or dry periods. The leaves are also very low in energy comprising only 5% sugars and starches on average.

Eucalypt leaves contain many toxic compounds similar to that of cyanide, which most animals cannot eat. This unique diet is shared only with possum and gliders, and provides koalas with access to a relatively untapped food resource. Koalas are able to break down the toxic oils using a specialised digestive system. First, the leaves are ground into a paste by the koala's heavily ridged molars, allowing any nutrients to be absorbed in the stomach. Toxins in the leaves are isolated by the liver and excreted as waste in their urine and faeces. The residue is then broken down by specialised bacteria in an elongated, coiled sac (the caecum) that branches off the large intestine before any remaining nutrients are digested.

Koalas are not born with this bacteria in their system and need to acquire it from their mother when they are young. The mother passes on this bacteria by excreting a sticky runny faecal substance called ‘pap’, which the young ingests instinctively, providing it with the bacteria it needs to eat the leaves in adult life.

Behaviour
Koalas can sleep for up to 20 hours a day, due to their low energy diet, and the intense amount of energy required to break down toxic leaves.

Koalas are mostly active at night (nocturnal) and around dawn and dusk. However, they can be seen moving during the day if they are disturbed, get too hot or cold, or need to find a new tree.

Koalas are solitary animals living within a network of overlapping home ranges, which allows contact between individuals for mating. Males will try to establish dominance over the home ranges of a number of females during the mating season. These home ranges in southern and central Queensland vary in size from 1km to 135km, depending on the density of the po[CENSORED]tion and the abundance of suitable food trees.

In spring, adult males begin to call as a way of advertising their presence to surrounding koalas. Males will seek out a mate and fight with rival males to establish their dominance.