A team of international scientists working in Australia have tracked the love lives of koalas, uncovering some curious behaviour and discovering that male koalas make their distinct bellows to avoid confrontation with competitors looking for a mate to breed with.
The University of Queensland's project chief Bill Ellis and colleagues in Australia, the US and Japan mapped what they believe to be the first look inside the social system of a large group of wild koalas on the Queensland central coast, Xinhua news agency reported.
Despite being renowned for their cute appearance, koalas have a range of very loud guttural grunts and howls.
"Unlike humans, who raise their voices in an argument, male koalas bellow their presence to avoid confrontation with other males in the breeding season," Ellis said in a statement released by the university.
"They can tell who's bigger from their calls, and stay away from them," he said.
"At the same time, they use their bellows to attract females."
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Ellis said the social system of the koala was poorly known, despite the fact they were a charismatic and well-known species.
"Much of the koala's social and mating behaviour remains unquantified," he said.
"We had thought that in the mating season male koalas would be fighting more, but instead found that the males bellowed to reduce physical confrontations with other males," he noted
"This allowed them to space themselves apart, with little direct mating competition, while at the same time attracting females and increasing the rate of male-female encounters."
The researchers also found that females spent more time together in trees during the mating season than in the non-breeding season.
The researchers followed the koala interactions using GPS tracking collars on wild koalas to learn about the species' mating system.
"Every koala in the study had a radio collar so we were able to map all their interactions, such as when female koalas dashed over several hundred metres to visit males in the middle of the night -- something which would be hard to do by visual sightings," Ellis said.
He said the researchers concluded that indirect male-male competition done by bellowing, female mate choice, and possibly female competition, mediated sexual selection in koalas.