Through the cacophony of birdcalls, the quintessential signals of spring and attempts at attracting mates, there is a low, deep growling sound. This rumble sets off a few more pig-like noises, but these aren’t pigs, these are koalas in their home bush lands of Australia. As you traverse the bush and giant orb weavers’ webs, you suddenly smell a musky eucalyptus-like odor, another telltale sign of a male koala.
Then, above your head you hear that deep growling grunting noise again and realize you have arrived. You ascend the tree and the smell gets stronger and there he sits, the male you have been searching for, your chosen mate.
This female koala adventure is what I, along with fellow collaborators, have been trying to understand by studying both the koala colony here at the San Diego Zoo, and wild populations living in the Australian outback. Though they are a relatively primitive species, koalas seem to have perfected their mating strategies. Throughout Queensland, Australia despite their solitary lifestyle koalas have certainly found effective ways to attempt to attract mates.
Males appear to be doing most of the “attracting” and are typically loud and smelly. If females are choosing their mates using male bellow calls and scent profiles, what exactly are these calls and smells communicating to them?
For the past 10 years, I have been studying the Queensland koala colony at the San Diego Zoo. As anyone who has spent time watching these cute creatures knows, they really don’t seem to be very active animals. In fact, they spend up to 20 hours a day sleeping so that they can process that poor quality, low nutrient eucalyptus diet that they so love. As a behaviourist, simply watching these adorable critters has really been just the beginning of untangling what is happening with these animals and their love lives.
Now, koala sensory ecology is coming into to play! Male koalas in particular are both loud and smelly. Combined, these two characteristics seem to be playing a role in their ability to find mates and make more koalas.
Through the use of high-tech recording equipment and collection of scent profiles, we are starting to examine what each of our males is communicating via their bellow calls and scent. We are starting to understand the simple but complex way that koalas find each other and reproduce successfully to ensure population growth in this species.
Jennifer Tobey, research coordinator, Behavioral Biology, San Diego Zoo Institute for Conservation Research.