Cute, cuddly koalas are some of the most recognisable animals on earth. Zoos are full of them. They feature prominently in children’s clothes, shows, books and toy boxes.

Heck, the little fur balls have even earned a cameo in an episode of The Simpsons.

But for all that brand recognition, we know scarcely little about how these mailbox-sized marsupials mate in the wild. This is because koalas are typically solitary, arboreal and nocturnal. Kind of makes things difficult if you’re a peeping tom biologist who wants to observe koala cuddle time.

Thankfully, a new study published this month in PLOS ONE was able to shed some light on the koala’s courtship habits. The researchers travelled to St Bees Island off the northeast coast of Australia and fitted the koalas there with special GPS tracking collars. 

Not only did this allow researchers to track males and females throughout the mating season, but proximity loggers in the collars also revealed when the koalas got within one metre of each other – a necessary prerequisite for koala coitus. (So that’s why the high school dance chaperone was always on your case about dancing too close!)

After they downloaded all the data, the researchers started noticing some pretty cool stuff. For starters, male koalas rarely square off with each other during the mating season as we see with many other mammals. William Ellis, an ecologist at the University of Queensland and the study’s lead author, says this is likely due to the male koala’s totally belligerent bellow.

If you’ve never heard a koala bellow, imagine a two-stroke lawn mower mixed with the coo of a Tyrannosaurus rex. (Or watch the video below.)

“Each koala’s bellow is unique,” says Ellis. “There are changes in the bellows that identify individuals, and these are probably related to the vocal folds in the vocal tract of the koala.”

Scientists think males use these sounds to carve out turf (a koala rendition of “Come at me, bro!”). After all, when koalas fight they risk falling out of their trees and broken backs are bad for business. A good ol’ fashioned screaming match seems to benefit everyone. Even the ladies.

You see, there is some evidence to suggest that female koalas prefer to mate with different males each year. To aid them in their pursuit of some strange, Ellis believes the females use the males’ bellows as indicators of uniqueness. This is because certain aspects of the male koala’s screams are dictated by the length of his vocal tract, which makes these sounds authentic signals of an individual’s size.

“Koalas can’t really cheat on this,” says Ellis.

Think of it like a more honest, koala version of Tinder. (Kinder?) All the females have to do is sit in their trees and sift through the bellows. 

Swipe left. Swipe left. Swipe left. Wait, this guy sounds different. Swipe right!

“It’s a really cool mechanism to avoid inbreeding,” suggests Ellis, “and probably explains why, even though the St Bees Island koalas have been on the island for over 100 years from an introduced group of about 12, they have maintained a pretty high genetic diversity.”

There’s obviously still a lot of work that needs to be done before we can close the case file on koala courtship, but Ellis’s paper is a fascinating example of how creative applications of technology can make connections where direct observation is tedious, impractical or impossible.

Hold up, isn’t that also the appeal of Tinder? Weird. 

Top header image: Paul, Flickr