Koala Facts

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How long do koalas live?

The oldest wild koala recorded by Friends of the Koala was a female over 19 years old. Generally, their lifespan is 7 to 12 years. Koalas are aged by assessing the wear of their teeth.

How big are koalas?

Northern Rivers’ koalas are similar in appearance and size to Queensland koalas. They have a short, thick, grey and white coat and are smaller than their southern counterparts. A male koala’s average weight is 7- 8kg and a female is 6-7kg. That is a bit bigger than a basketball when they are curled up in a tree.

Coming into the world?

Across the region, koalas mate throughout the year, but the mating season peaks between November and January.

Koalas are the size of a small jelly bean when born; their eyes are shut, ears stuck to their head and they have no fur. They take a precarious journey from the cloaca, crawling into their mother’s pouch and attaching themselves to one of their mother’s two teats. Koala joeys spend the first 6 months of their lives in their mother’s pouch, and during this time grow fur and open their eyes. From 7-12 months they spend their time on their mum’s tummy, back or close by, learning how to navigate the treetops and adjusting to a diet of eucalyptus leaves. The next few months are spent in the same vicinity as their mother as they become weaned and fully independent. Females often stay in the same area as their mothers, but young males usually disperse.

The koala’s breeding cycle [344KB]
(source: Bill Phillips. Aust Govt. Publishing Service. 1990.)

What do koalas eat?

Koalas survive mainly on a diet of eucalyptus leaves but they do not eat all species of eucalyptus. Their preferred trees in the Northern Rivers are Forest Red Gum, Tallowwood and Swamp Mahogany although they eat many other eucalypts as well. The trees koalas prefer to eat and use for shelter depend on the particular area and its surrounding habitat. For the Northern Rivers, non-eucalypts such as Paperbarks and She Oaks are often used. A koala’s metabolism is finely balanced between nutritional needs and energy requirements. Habitat disturbance upsets the balance because koalas must range further afield for their specific food requirements.

Koala tree preferences

Why does a koala choose a particular tree in the forest to feed on? Awareness of the extreme fussiness of the koala in its choice of food dates from the time a koala was first taken into captivity in 1803. Failure of early attempts to exhibit koalas overseas where Eucalyptus foliage was not available and the mortality of many koalas in zoos even in Australia in the early 1900’s reinforced this view. Observations of feeding patterns of koalas in captivity showed that their diet changed at certain times of the year when animals rejected certain species of eucalypt that they showed a strong preference for in other seasons. These same habits have also been observed in the wild.

Field studies seem to indicate that koalas’ tree preference is influenced by their social organization, the structure of the tree and the chemistry of the leaves. Observed differences in tree species preference between sexes, and the preference for individual trees within species, may have their basis in the social organization of the koala. Although adult koalas are rarely seen in the same tree and appear to avoid one another, they nevertheless form clusters in which the home range of the dominant male and several females overlap extensively. Frequent use of a small number of trees by these koalas may provide a means of communication thus maintaining the cohesion of the cluster. Another theory is that the frequent cropping of the tree results in many new shoots being produced, which in turn attracts koalas.

The only structural features of trees that seem to attract koalas according to scientists are tree girth and height. Obviously the bigger the tree, the more food available and therefore the need to move between trees is reduced. This then reduces the energy expended by the koala and also reduces the chance of predation.

The preference for a narrow range of species within the huge Eucalyptus genus appears to have its basis in the chemistry of the leaves. Attempts to identify this basis have focused on either the nutritional or the toxic qualities of the foliage, and for various reasons no real basis has been identified.

Some clues as to why they choose one tree over another may be gleaned by studying the animals in their natural environment. Koalas first sample leaves while riding on their mothers’ backs and so become familiar with the foliage of the trees used by their mothers, but whether this influences their later choice of species has not yet been determined. Koalas frequently draw a branch of leaves to the vicinity of the nose before rejecting or accepting foliage. This will occur in a tree of a preferred species as well as when they are confronted by foliage from different species in captivity. This behaviour suggests that preferred browse food is identified by smell, however what they are actually smelling still remains a mystery.

Eucalypt foliage is considered a poor source of nutrients. It has been estimated that the entire amount of food eaten by a koala in a day (between 500grams and 1 kilogram of eucalypt leaf) contains about the same energy as a bowl of Cornflakes! No wonder the animals sit in the tree seemingly sleeping all day – they don’t have any energy to do anything else. The Eucalypt species favoured by koalas are those often found on fertile soils suggesting that nutrient quality may be an ultimate factor in species preference. The preferred species also tend to be associated with drainage lines or shallow water tables – an important factor in times of drought and at other times encouraging the growth of new tips which have been shown to be richer in nutrients than older leaves.

All in all, mystery still surrounds the whole issue.

For further information, please contact Mark Wilson (Nursery Manager) at nursery@friendsofthekoala.org or phone 0413 339 554.

Looking for koalas?

Koalas are known to live in an area by:

  • scratch marks on tree trunks
  • scats on the ground
  • calls or sounds – video of a male koala grunting
  • sightings
  • watch out for all the signs of koala activity and report sightings to us so accurate records of activity and sightings can be maintained.

Male or female?

Male koalas are generally larger than females and their testicles are sometimes visible. They have a longer, broader face and as adults are more muscular. At sexual maturity (2 -3 years) they develop a scent gland on their chest which looks like a dirty, vertical mark down the middle of their upper chest. They use this scent glad to claim their territory by rubbing it against the trunks of their trees.

Females are generally smaller, with fluffier ears. They have a rounder, softer face and are smaller in size.

Having said that, some females have broad faces and some males have lovely fluffy ears. There are always exceptions to the rule with koalas.

Where do koalas live in the Northern Rivers?

Koalas are widely distributed across the Northern Rivers of New South Wales although their numbers vary depending on available habitat. There are regular sightings in all the local government areas of Ballina, Byron, Kyogle, Lismore, Richmond Valley and Tweed. Koalas are found in areas with extensive bushland however they also survive in urban areas although they are much more vulnerable there to threats such as vehicles, dogs and swimming pools.

Koalas are known to use people’s yards and even the streets of some towns and villages. Sightings occur in Byron Bay, Kyogle, Clunes, Dunoon, Federal, Pottsville, Goonellabah and Wyrallah, to name a few. In most parts of urban Lismore koalas are commonplace, however there are concerns that koala numbers have decreased in recent times as habitat has been greatly reduced and that which remains is fragmented.

30 other facts about koalas

download all FOK Fact images in one ZIP file [13MB]

Did you know that koalas are tree huggers? They hug trees to keep cool during the warmer months.Koalas are fussy eaters. They will sniff each leaf to determine which is the tastiest.Koalas are NOT BEARS. They are MARSUPIALS.Did you know that koalas sleep for 18 to 20 hours a day?Koalas have two thumbs, so no wonder they’re awesome tree climbers.Koalas do NOT get drunk or high on eucalyptus leaves. Their diet is simply low in nutrients thus they’re very tired and sleep for long periods.Koalas have favourite foods that vary from Region to Region. In the Northern Rivers this includes Forest Red Gum, Swamp Mahogany and Tallowwood.Just like people, koalas have individual finger prints and personalities.Baby koalas are called joeys.After a 35 day gestation period a joey is born. Bald, blind and deaf it crawls into the pouch and attaches to a teat where it stays for the first 6 months of its life.When we tag koalas a female is tagged in the right ear and a male is tagged in the left ear.A koala’s closest relative is the wombat.Koalas are distributed along the Eastern seaboard of Australia. Their distribution is limited by temperature, altitude (>800 m above sea level), aridity, and leaf moisture content.Adult koalas consume 250-500g of leaf per day.Koalas are hindgut fermenters. They have the longest (relative to body size) caecum in the world. They have a unique balance of instestinal bacteria (primarily anaerobic), as well as specialised yeast protzoa.A joey the size of a rockmelon or smaller should still be with its mother.Male koalas have a broad head and nose, short, stocky ears, a scent gland in the middle of their chests, external testes, and can grow up to 10 kg in Northern NSW. Of course there are always exceptions to the rules.Female koalas have a narrower, more refined face and nose, fluffy ears, a pouch, potentially a joey, and grow up to 6kg in Northern NSW, but of course there are exceptions to the rules.Cystitis or ‘wet bottom’ is a symptom of Chlamydia, which is an STD and the most common reason a koala comes into care. If caught early, cystitis can be treated with a course of antibiotics.Conjunctivitis is a symptom of Chlamydia which is an STD and the most common reason a koala comes into care. It is treatable with antibiotics.Koalas don’t have knee caps.Koalas are aged by the wear on their teeth.The koala’s scientific name is Phascolarctos cinereus, which means ashy or ash-coloured pouch bear, although in fact they are not bears they are marsupials.In NSW koalas are listed as vulnerable under the Threatened Species Conservation Act 1995.Koalas might look cuddly but they are wild animals with very sharp teeth and claws.The fur on a koala’s bottom is extra thick to provide a ‘cushion’ for sitting on hard perches and has a ‘dappled’ appearance making koalas difficult to see from the ground.Koalas live in colonies; however, they are not social animals.As koalas do not usually drink they get most of their moisture from the leaves they eat.Historically, koala populations have declined due to habitat fragmentation and hunting for their fur until 1927, from which they haven’t recovered. Current threats to koala populations are ongoing habitat loss, urban risks dogs and cars and diseases such as chlamydia and retrovirus.At birth a joey is equivalent to a foetus in development. At 6 months a joey is equivalent to a newborn.