Researchers tracking the love lives of koalas have uncovered distinct behaviors in the marsupials that facilitate communication and mating in their group.

Bill Ellis and colleagues have mapped out what is believed to be a first look at the inner workings of the social system of koalas living in the wild in St. Bees Island near Rockhampton, Queensland. One of the most notable of the behaviors the researchers discovered was that male koalas bellow to make their presence felt and avoid confrontations with other males during breeding season.

A koala's bellow is proportional to their size so those who hear them can assess who's bigger, moving away if needed to avoid a confrontation. Raising voices maintains the peace in a group of koalas whereas the same would instigate arguments in people.

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

Koalas are undoubtedly well-known but not a lot about how they move in their own society is known. In fact, mating behaviors have not been quantified.

It's typical for males to compete for the attention of females during mating season and this meant fighting with each other. However, that's not the case with koalas.

By bellowing, koalas create spaces for everyone, situating themselves apart to avoid direct competition. But as the bellows also attract females, the action also increases male-female encounters which increase the success of mating.

To track the koalas, the researchers used GPS-enabled collars. All koalas that are part of the study were fitted with radio collars that made it possible to keep tabs on their every move. Say, a female dashes several hundred feet (the females usually stay together) to meet up with males in the dead of the night. The collars can track this kind of activity, which is something that visual sightings cannot.

After discovering that certain behaviors facilitate sexual selection in koalas, the researchers are taking the next step by carrying out paternity analysis of offspring resulting from male-female encounters during the study. This will show which of the encounters were successful and, using data correlating with information from radio tracking, why.

The study received funding support from Queensland Smart Futures and the San Diego Zoo and Koala Education and Conservation Program partners. Other authors include: Sean FitzGibbon, Stephen Johnston, Ben Barth, Jenny Seddon, Fred Bercovitch, Damien Higgins, Alistair Melzer, Bill Whipple and Geoff Pye.

Photo: Nicki Mannix | Flickr