The easiest way to identify an animal’s sex is to look at their genitals. But this is not always possible, especially when it comes to wild koalas.
Koalas usually spend a fair bit of time sitting on their bum high in a tree, hiding the obvious sex traces. So how to tell male and female apart?
The answer is: look at their chests! And no, female koalas don’t have nipples on their chest in case you are wondering. Their nipples are in another place, but this is a subject for another blog.
The second most obvious difference between male and female koalas is the scent gland on the chest of males. Koalas scent glands are quite easy to see in male adults: a dark-edged bare patch on their chests.
Side note: female koalas might present a small crease on their chest, but they are very small and with no brown colouring at all. Notice the small crease on female Djadja’s chest:
Male scent glands take years to form. So when a koala is young, it can be hard to differentiate males from females. Let’s have a look at Koala Clancy’s scent gland through different stages of his life.
In this pic, he’s only a baby – 19 months old. His scent gland is not much more than a female-like crease in the fur. But note, it does have a brown colour.
Here he is again, Koala Clancy at 20 months: Even when he was stretched out, there wasn’t much to it. But can you see a dark bare patch starting to form?
And here he is at 3 years old, a young adult koala. Brown-edged scent gland, and now some more bare skin showing:
At 5 and a half years old, Koala Clancy is entering his prime breeding age and his scent gland is large, dark and obvious:
And now, at over 6 years old his scent gland reaches all the way down his belly, and the bare skin in the centre is plain to see:
As you can see, the scent glands are quite obvious on mature male koalas, but not so much on young male koalas. To an untrained eye, it would be possible to confuse a baby 19 month old Koala Clancy with an adult female, if just looking at his scent gland.
So, let’s recap to make sure you are a pro telling the difference between male and female koalas.
The first step is to figure out whether you’re looking at a full adult or a very young koala. Very young koalas (1-2 years old) are usually smaller than adults. They have chubby faces, smooth thick fur that is usually grey, not brown. They look more like teddy bears at this age than any other.
In this photo Cuddles is about 11 months old:
Then, once you’ve established the koala’s age, have a really good look to check if their genitals are visible. Male koalas’ testicles are obvious from a very young age. Can you see them in this pic of Koala Gulkurguli? Yes? Great!
If the koala positioning doesn’t allow you to check the sex, move to step 3.
Look at the koala’s chest and see if you find a crease on it. If you find a full-grown adult with a dark-edged bare patch on their chests, then it is a male.
If the koala is a full-grown adult, and the crease on their chest is small, light-coloured and shows no bare skin – then it must be a female.
Sometimes a koala won’t show their chest or their bottoms, and then you just have to guess. Or wait – koalas move on average every 30 minutes. If you wait long enough you’ll eventually see. You might even get extra lucky and watch the koala descending the tree and walking on the ground.
So here’s a test. Based on everything you’ve learned, are the following 3 photos of adult females or young male koalas? Please answer in the comments and I’ll tell you if you’re a Koala Expert!