Adult female koalas have a relatively clean white chest and a backward facing pouch for their young. This type of pouch protects their young from injury while moving around from tree to tree. This is a shared trait with wombats who use this to protect their young from being covered in dirt during when digging burrows. 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.
This removes the need for a koala to climb down a tree for a drink of water, except during very hot or dry periods. 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. 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 km, depending on the density of the population 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. Males begin mating at three to four years of age. Females begin mating, and can breed, when they are two years of age, generally giving birth once a year, for the next 10 to 15 years. The gestation period of a female koala is 35 days, after which she gives birth to a single joey. Female koalas are also capable of giving birth to twins, however this is quite rare.
Birth usually take place between the months of November and February. The young stays in the pouch for the next six months before emerging for the first time. The joey will then spend between six and 12 months riding on its mother's back. By 12 months of age, the young is weaned and takes up a home range, which overlaps with its mother, for much of the next year. Between the age of two and three years, these young disperse beyond their original home range to establish their own range, usually during the breeding season.
On average, koalas live for 10 to 12 years of age in the wild. In both cases the ability to conduct a degree of chemical analysis is involved. This means the koala olfactory ability is above most mammals.
Koalas are solitary animals, yet they do live in a colony. This means they recognise the other colony members, and therefore distinguish koalas that are strangers. They do however recognise the smell of other koalas. They also recognise the bellow of other males. Most of the time however, koalas are quiet. Yet a koala does not move through the territory of another koala unnoticed, even if it makes no vocal sounds.
How does a regular colony member know another koala has been in their territory? We observe that both sound and scent are used to communicate more during the breeding season — a time when koalas are actually communicating the most. However, koalas have a home range within their colony area and they have home trees within their home range.
Their dominant nose also helps people to easily differentiate in between koalas and bears teddy bears too. However; it is not necessary that a white koala will always have a pink-colored nose. Some white koalas have also been spotted with the same black color of their nose as well. Interestingly; the koala researchers have also noticed that each koala has its own unique pattern of nose under its nostrils.
Its nose can also differentiate different species of eucalyptus leaves and it also determines which leaves to eat and in what season. Furthermore; a koala can also evaluate the levels of nitrogen and toxicity within the eucalyptus leaves through its nose as well.
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