Male koalas let out distinct bellows to avoid confrontation with competitors, according new research on their love lives.
Researcher Bill Ellis and colleagues have mapped what they believe to be the first look into the social system of a large group of wild koalas at St Bees Island near Rockhampton, Queensland.
“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 says.
“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.”
Ellis, a research fellow in the University of Queensland School of Agriculture and Food Sciences and the Sustainable Minerals Institute, says the social system of the koala was poorly known, even though they’re a charismatic and well-known species.
“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 says.
“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 shared spaces or trees during the mating season than in the non-breeding season.
The researchers mapped koala interactions using GPS-enabled 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 meters to visit males in the middle of the night—something which would be hard to do by visual sightings,” says Ellis.
He says the researchers conclude that indirect male-male competition, female mate choice, and possibly female competition, mediated sexual selection in koalas.
“The next step for us will be to do a paternity analysis of the offspring produced during male-female encounters and correlate that with our radio tracking,” he adds. “This will help us to see which interactions were the most successful, and try to work out why.”
Additional researchers from University of Queensland, San Diego Zoo, Central Queensland University, University of Sydney, and Kyoto University contributed to the study in PLOS ONE.
Funding came from Queensland Smart Futures through a Queensland State Government Koala Funding Grant, San Diego Zoo, and the Koala Education and Conservation Program EAZA/AZA partners.
Source: University of Queensland