Written By Yan Zhuang
One would think that koalas are easy to find — and count — because they are large, fluffy and mostly immobile since they are prone to sleep for about 20 hours a day. Not so.
“It’s the fact that they don’t move much that makes them hard to spot,” said Desley Whisson, a Wildlife Ecologist at Deakin University in Victoria.
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This makes the Australian government’s effort to count the population of the iconic marsupials and record where they live all the more daunting. In November, the government not only announced it was committing 2 million Australian dollars ($1.5 million) to fund an audit of the native species, it would also use a host of new methods to do so.
Estimates of koala populations have historically varied wildly. In 2016, scientists estimated there were more than 300,000 koalas in Australia. In mid-2019, the Australian Koala Foundation estimated that fewer than 80,000 remained in the country, and said the number could be as low as 43,000. Concern and confusion over the koalas’ numbers intensified during Australia’s devastating bush fires last year, leading to news articles that the animals were “functionally extinct.” But scientists challenged the accuracy of that narrative.
Even before the bush fires decimated koala populations, there were growing fears that the animals were in trouble. Scientists and conservation organizations say the loss of habitat because of land clearing is sending koalas more and more into urban areas — and occasionally into people’s Christmas trees — where they are imperiled: getting flattened by cars and attacked by dogs. Populations of koalas under stress are also more prone to deadly diseases, experts say.
An accurate koala census has been difficult. The last national count, conducted in 2012, simply asked scientists to estimate the number in certain regions, leading to a range of approximations, such as 33,000 to 153,000 for one state.
“For all our focus on koalas, scientists are telling us that there is a serious lack of data about where populations actually are, how they are faring and the best ways to help them recover after the devastating bush fires,” the Federal Environment Minister, Sussan Ley, said in a statement at the time of the announcement.
The traditional method of counting koalas was to simply have people see how many they could spot. But when the marsupials are high up in trees, staying still and obscured by canopy, they’re easy to miss with the naked eye, Whisson said. Counts can vary wildly from person and person and depending on conditions, so that method can reap a figure that is 20% to 80% of the true population of any one location.
“For me personally, I see more koalas in the morning than the afternoon,” she said. “By the afternoon, you might be getting a bit tired, your eyes might be a bit tired, and you want to get home so you might rush it a bit.”
Because this is Australia, a venture into the bush to count koalas will probably mean fighting off snakes or various creepy-crawlies that bite, making it hard to focus.
“All sorts of things can take your mind off what you’re looking for and can alter the probability of you seeing a koala,” Whisson said.
So scientists decided to employ a few other methods. Koala droppings — small brown pellets — found at the base of trees can determine if they live in an area. Detection dogs can locate both koalas and their droppings. Male koalas bellow during breeding season, so scientists can leave recording devices at sites to detect if koalas are around.
Koalas in remote or hard-to-reach locations can be counted using heat-seeking drones, but only in colder weather, since the animals’ fur provides a lot of insulation and they don’t give off much heat.
If all of those methods are used together, and used well, a count that has just a 10% margin of error can be accomplished, Whisson said.
Whisson stressed that Australian officials cannot wait for the results of the audit to address the issue of declining populations. There is already abundant data to show that koala numbers are declining in parts of country, she said.
“If it takes a few years for the count to be produced, we’ll see numbers continue to decline in that time,” she warned.
In fact, 23 conservation groups demanded last week in an open letter titled “Koalas Need More Than a Population Census” that the government do more about habitat protection. “Degradation of koala habitat has increased under your government, and continues right now,” said the letter, which was addressed to the Environment Minister. “Koalas cannot wait for a national count to reveal their numbers. They’re on a knife-edge now.”
Driving home the urgency, Rebecca Keeble, Oceania Regional Director for the International Fund for Animal Welfare, was quoted as saying, “Counting koalas is like counting the deck chairs on the Titanic as it sinks.”