Koalas are usually regarded as solitary animals, but new footage is revealing a more gregarious side.Darcy Watchornat Deakin University, Melbourne, Australia, filmed male koalas grooming each other, playing, smelling each others genitals and spending long periods together in close physical contact. They were being ridiculously cute, says Watchorn. AdvertisementAdult male koalas (Phascolarctos cinereus) generally avoid each other. If they do interact it is usually aggressive and involves fights over females, often leading to serious injuries.Watchorn thinks the extraordinary friendliness he observed was the result of too many koalas being crowded together. The population at the colony at Cape Otway in southern Victoria exploded after koalas were released there in the 1980s, but habitat fragmentation meant there was little space in which they could disperse.He captured the behaviour in 2015, but only released the footage now after realising the significance of these interactions, the likes of which have never been seen before. Unmissable news about our planet delivered straight to your inbox every month.Sign up to newsletterOn the flip side, he also observed and filmed a darker side of koala behaviour. It involved an unsuccessful mating between a male and a female, who had a young joey that had only been out of its pouch for a few days. The joey climbed onto the males back while its mother ascended into the tree canopy without him.Whilst it was incidental, it kind of looked like he stole the joey and ran away, says Watchorn. Then, after a little bit of time, the joey was quite annoying him. It was trying to come off his shoulder, around to his front where they would often sit with their mothers.Eventually, the male grabbed the joey, bit him and forced him out of the tree. He fell 7 metres to the ground.Watchorn realised that without intervention, the joey would almost certainly be eaten by a fox or die of exposure. I should have sat there and observed what happened without intervening, but, instead, I scooped up the joey, caught the mum and reunited them, he says. At the end of my study, a few months later, that joey was looking really good and big and fat and healthy.Journal reference:Australian Mammalogy DOI: 10.1071/AM24033Topics:animals