A team of international scientists has tracked the love lives of koalas, uncovering some curious behaviours and finding that male koalas make their distinct bellows to avoid confrontation with competitors. The University of Queensland's Dr Bill Ellis and colleagues in Australia, the US and Japan have mapped what they believe to be the first-look inside the social system of a large group of wild koalas at St Bees Island near Rockhampton, Queensland, Australia. 

"Unlike humans, who raise their voices in an argument, male koalas bellow their presence to avoid confrontation with other males in the breeding season," Dr Ellis said.

"They can tell who's bigger from their calls, and stay away from them.

"At the same time, they use their bellows to attract females."

Dr Ellis, a research fellow in UQ's School of Agriculture and Food Sciences and the Sustainable Minerals Institute, said the social system of the koala was poorly known, despite the fact it was a charismatic and well-known species.

"Much of the koala's social and mating behaviours remain 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.

"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."