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Koalas with grunt



This little joey probably has an illegitimate brother or sister or two (Source: Reuters)

The grunts and bellows of amorous male koalas are so loud they can sometimes be heard several kilometres away. You're most likely to hear the sounds of their gruntings at sunrise and sunset.

Koalas are frequently down on the ground at this time of year, moving between trees in their search for mates and territory. If they live near an urban settlement, this is when koalas are most likely to be attacked by dogs or hit by cars. The Australian Koala Foundation says at least 4000 koalas are killed each year by cars or dogs, apart from those who die when forests are cleared.

These tree-dwelling pouched marsupials are very territorial, and the larger individuals command a home range of many hectares. As the spring breeding season approaches, the male patrols his trees in search of females who are ready to mate, and, being a polygamist, the more girls the better.

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Marsupial Idol

The action starts when our dominant koala spots another male hanging out in his territory. Outraged, he tries to scare off the intruder with a loud, harsh cry. It's a weird and spine-chilling bellow, half way between water gurgling down a drain and a log being hacked to pieces by a blunt saw.

If this doesn't work, the big guy moves in for the attack. He rushes up and tries to grab his opponent, who usually retreats to the end of the branch, or even hightails it down the tree.

If the attacker manages to tackle the other koala, he thrusts one arm around his opponent's shoulders and bites him hard on the elbow, often leaving a bad wound. Koalas have even been pulled right out of a tree by their adversary during combat.

Because these violent encounters need plenty of strength and experience, most male koalas are lucky to get a mate before they turn four or five years old, even though they are physically mature by about 18 months of age.

The blokes aren't the only ones to voice their feelings. Female koalas too will vocalise: letting out a snarl or scream if they are feeling threatened or during sexual contact. But whereas males specialise in terrifying howls, females mostly murmur and click quietly to their joey (baby koala), who returns their affections with its own tiny squeaks.

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Is there anybody out there?

Koalas aren't the most energetic animal - spending up to 20 hours each day resting or sleeping and only one or two hours actively moving about. So vocalisations are important for them: these bellows not only enable koalas to be heard over long distances, but also save fighting energy, by signalling to other koalas that this is a dominant individual so not to bother attacking.

Fact file:

When: Northern Australia - mating from July-April (babies born from August)

Southern Australia - mating from September - February (babies born from October)

Where: East coast, from far north Queensland to Victoria and coastal South Australia. Koalas will live in tall coastal eucalypt forests, but are never found in rainforests or the desert.

What to look for: A white flash of chest hair, scratching on trees, a powerful musky smell.

What you might not know about koalas: They eat up to 1kg gum leaves and do up to 150 poos each day.

Koala hotspots: Kangaroo Island (SA), Tower Hill Reserve (Vic), Barrington Tops National Park (NSW), Canarvon National Park and Lamington National Park (Qld). Koalas are not found in the wild in WA, NT or Tasmania.

The home ranges, which koalas maintain by using their grunts and bellows, are taken very seriously by other koalas in the vicinity. Even after a koala dies, others won't invade its home range for at least a year, which is about how long it takes for the scent markings and scratches of the previous occupant to disappear.

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Fussy eaters

One thing that highly influences how a koala chooses its habitat is the suitability of the trees. Koalas are highly specialised feeders, preferring only about 10 per cent of Australia's nearly 600 species of eucalyptus tree. In the south, the absolute favourite koala tucker are manna gums (E viminalis) and swamp gums (E ovata). In the north, their preference is for forest red gums (E tereticornis), tallowwood (E microcorys) and grey gum (E punctata). They also enjoy snacking on blue gum (E globulus), river red gum (E camaldulensis) and flooded gum (E grandis).

Although koalas occasionally eat small amounts of bark and twigs, their diet is pretty much restricted to gum leaves. But despite the narrow diet, koalas are often found sitting in trees which are not their food trees, such as wattles, she-oaks, paperbarks and even radiata pine, none of which offer them anything edible. Researchers believe koalas may seek out these trees to shelter in during windy, rainy or very hot weather.

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Eau de Koala


There is nothing quite like the heady aroma of a koala in season which, once experienced, is never forgotten. The aroma is something like 'a pungent acrid musk, laced with a hint of eucalypt' as koala expert Scott Buckingham describes it. The smell comes from both the urine and from a scent gland on the male's chest which he rubs vigorously against the branches as he climbs. So beware if you are looking for koalas, you'll probably smell them, even before you hear them and certainly before you see them!

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Further info

Australian Koala Foundation

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Locating Koalas in the Australian Bush, Scott Buckingham, 1999, Bolwarrah Press

Tags: endangered-and-protected-species, animal-behaviour, marsupials

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Published 05 October 2006