Quirks and Quarks

New book explores the unique biology and uncertain fate of Australia's iconic koala

Author and biologist Danielle Clode talks about her new book, Koala: A Natural History and an Uncertain Future.

Koalas are the poster child of conservation, says author and biologist Danielle Clode

A koala in a short tree on the left with a mouthfull of green leaves, author Danielle Clode is on the right
A koala munches on eucalypt leaves while posing for this photo with author Danielle Clode (Submitted by Danielle Clode)

Australians won't soon forget the 2019-2020 bushfire season — the so-called "Black Summer." Thirty-four people died, thousands of buildings were incinerated, millions of hectares of bush and forest destroyed, and billions of land vertebrates were killed. But the face of this wildfire tragedy quickly became the koala. Heartbreaking images of rescued koalas with scorched feet, noses and ears were seen around the world. Those were the lucky ones; many thousands were not so fortunate. 

Koalas had survived fires before, although likely not as devastating as this megafire. And throughout their evolutionary history, they have experienced climate change, disease, loss of habit, increasing drought, predation and being hunted to near extinction. But they are still here. 

Biologist and writer Danielle Clode was inspired to tell the story of how this endearing and iconic animal lives, its changing environment and its relationship to humans, after bushfires threatened the very koalas in her own backyard. 

She spoke with Quirks & Quarks host Bob McDonald about her new book , Koala: A Natural History and An Uncertain Future.

Let's start with the close-up picture there. Tell me about the koalas in your own backyard.

Well, I'm really fortunate to live in a part of Australia where koalas are quite abundant and regularly seen. And that's really unusual, because in most parts of Australia the most common place to see a koala is in a wildlife park or a zoo. But here in the Adelaide Hills, they're having a bit of a boom. And then we've got an expanding population. So we hear them calling every spring. We hear the grunting bellows of the male koalas advertising their wares in the trees and the battles as well  see them crossing the road or sitting up in a gum tree eating the eucalyptus leaves, grunting.

Koalas are... the poster child for conservation.- Danielle Clode

I've heard they make quite an interesting sound. 

Yes, they do make a bit of a racket. The males have a really a sort of a deep wheezy cough bellow kind of sound. Some people say it sounds like a demonic donkey. Females, when they're not interested in the male's approaches, they scream and squeal and make a lot of racket for sure. 

Well, how did these koalas in your backyard inspire this book? 

Well, I guess I was really interested after the Black summer bushfires of 2019 and 2020, which generated international concern and anxiety about koala. Not just koalas, but wildlife generally. But certainly koalas are the face of that concern, I guess. I was really interested to know why it was that koalas seemed to be in such dire straits on the east coast of Australia and particularly the northern states of Australia, and yet they were booming in my area. We also had some pretty catastrophic fires in South Australia as well at the same time, and a large koala population that had actually been established as a refuge for koalas on Kangaroo Island was absolutely decimated.

Book cover, two koalas in a tree on a white background
Biologist Danielle Clode's new book is called "Koala: A Natural History and an Uncertain Future". (W.W. Norton & Company)

I know that you live in the Adelaide district. Where else are koalas found? 

The natural spread is currently pretty much from where I live in the middle of the South Coast of the country, spreading around the coast through the forested areas of Australia — so right around the southeast corner and then up the eastern coastline. So just up into the tropics there. So it's kind of like a forested band, a hook around the southeast corner. 

Koalas are, of course, famous. Are they still the national icon of Australia? 

They're certainly one of the most identifiable and well-known species. We've got a lot of very charismatic animals, wombats and kangaroos and things like that. So they've got a bit of rivalry there. But I think today certainly koalas are, in conservation terms, the poster child for conservation. Internationally, they generate huge amounts of funding for koala hospitals and things like that. They're the only species I can think of that has their own dedicated hospitals. All the other animals just go to wildlife areas. 

Despite all that worldwide fame, we don't really know a lot about them, Darwin didn't even mention them on his famed Beagle voyage. So why do you think they're so understudied?

They didn't generate the same interest when Europeans and scientists first started looking at Australia in the same way as things like the platypus and the kangaroo and the wombat. They were really interested in them. But koalas were neglected, and I can only assume that was perhaps because they were less abundant in the area where colonization first started. And generally they're quite a discrete animal. Their fame really rose when they were under threat, I think.

A koala drinks from a water bottle offered by a firefighter.
Many koalas were lost in the bushfires of 2019-20. This is one of the lucky ones. (Oakbank Balhannah CFS/The Associated Press)

They were haunted almost to extinction. And yet they're still around. What does that tell us about their survival abilities? 

The koalas were hunted to near extinction in the late 1800s, early 1900s when the market for fur was really, really strong in North America and Europe. So millions of pelts of koalas, wombats, possums and other Australian animals were shipped overseas during that time and the koala populations were completely decimated in the southern states. So they almost certainly went extinct in South Australia and they were nearly extinct in Victoria. There were just a few hundred [koalas] left in that area. So it's quite shocking.

Let's talk about their diet. They don't make it easy on themselves, do they? 

No. We think of koalas being specialists on eucalypt trees, and we often think of eucalyptus as being a single uniform thing. But in actual fact, eucalypts are a very diverse group of trees. In Australia, they're the dominant forest tree. So if you're going to be a forest dweller, being able to eat eucalyptus is definitely an advantage. But of course they're highly toxic as well. So they generally have compounds in them that make mammals feel sick if they eat them. And koalas need to have very specialized digestive systems in order to both digest the really tough leaves and also to remove the toxins, and they're quite rare in their capacity to do that. 

What are the greatest threats to koalas today?

Most definitely the biggest threats are habitat loss and climate change. So those things are obviously connected. The main problem koalas have is lack of habitat. We have destroyed most of the forests and we continue to clear land along the east coast of Australia, and Australia has a bad record at the moment of land clearance which is continuing through loopholes and exemptions in legislation that we really need to close and fix. But you know, climate change is a big factor that we really don't know how that's going to impact the forests, whether that's going to change the toxicity of the gum leaves. So we really need to do our best to mitigate that as much as possible. 

The one thing is that koalas are able to live with humans. We just need to plan for that. It is possible for koalas to live in those areas, provided they have good linear forested parks that move through the cities, that they have safe passage over or under roads, that they're protected from dogs, and that we maintain tree cover in our cities. 

I think koalas are a robust and resilient species. That said, I think that when they're declining in particular areas, that's a real warning sign for us that we need to be taking better care of our environment. So they're a bit of a canary in the forest, as it were.

This interview has been edited for length and clarity.