Koalas are adorable, chlamydia-riddled fluffballs – and functionally extinct, say campaigners.
The sad news comes courtesy of the Australian Koala Foundation, who say that there are now fewer than 80,000 koalas in the wild. The figure is significantly lower than previous estimates and is resulting in excessive inbreeding that experts say will harm the viability of any future generations.
The warning comes just weeks after a UN report revealed close to a million species of plants and animals are at risk of extinction within the coming decades unless we see “transformative change”.
Functional extinction stands in stark contrast to numerical extinction. The latter being when a species has declined to just a handful of individuals so that there is no chance of future breeding. Just think of Lonesome George, the Pinta Island giant tortoise, or Sudan, the northern white rhino.
Rather, an animal becomes functionally extinct when there are just not enough sexually mature adults to ensure a sustainable population, be it because of poor health, sparse distribution, age, or a simple lack of numbers.
A 2013 paper in Nature found that this unfortunate phenomenon occurs more frequently than previously thought. Using natural and computer-generated food webs, researchers discovered that many a species can become functionally extinct if a population falls by just 30 percent.
And while 80,000 might sound like a lot of koalas, it is well below previous estimates, Christine Adams-Hosking, a postdoctoral research fellow at the University of Queensland, wrote in a piece for The Conversation. What’s more, the Australian Koala Foundation suggests this figure may be inflated and actual numbers could be as low as 43,000.
“It’s hard to say exactly how many koalas are still remaining in Queensland, New South Wales, Victoria, South Australia and the Australian Capital Territory, but they are highly vulnerable to threats including deforestation, disease and the effects of climate change,” Adams-Hosking, who has studied the effects of climate change on koala distribution, explained.
As recently as 2016, a project to calculate koala populations reported steep declines across the country – with an estimated decline of 24 percent across the past three and future three generations. (In Queensland, the figures were even more shocking, with a predicted drop of 53 percent.) It is also worth noting that the same project’s estimation for koala numbers across Australia was 329,000. I.e. a lot higher than those calculated by the Australian Koala Foundation this year.
Adams-Hosking points out that while koalas are still breeding, the amount of inbreeding taking place in some populations is threatening the viability of future generations. Studies on the Koala Coast, near Brisbane, for example, highlight this lack of genetic variation.
But dwindling genetic diversity isn’t the only threat facing koalas. Human-caused climate change and the bizarre weather it brings (severe drought and road-melting heatwaves, for example) are also causing problems, as is the rapid destruction of their habitat.
Individuals inhabit large territories of 100 or so “home trees”, meaning it is especially important to make sure the critters have plenty of space to roam. But Australia has some of the highest land clearing rates in the world, says the Australian Koala Foundation, and some 80 percent of koala habitat has already been removed.
Koalas are some of Australia’s oldest residents, with fossilized remains confirming the presence of koala-like creatures on the island 25 million years ago. Let’s hope this news will mobilize efforts to save them.