Rising temperatures are exacerbating threats to Australia’s iconic koalas, an already vulnerable species, scientists warn.
Koalas are increasingly facing heat stress and even death when temperatures exceed a certain threshold, according to a paper published in Biology Letters on Tuesday.
An analysis of nearly 12,000 koala rescue records across New South Wales indicates koalas’ risk of admission into care and death increased sharply when the average maximum temperature was 27 degrees Celsius — or 80.6 degrees Fahrenheit — or above.
Inland north-west koala populations faced the greatest risks, the researchers found.
Before this study, there had been many observational reports of koalas dying during heatwaves, particularly during extreme summer temperatures in Australia, Valentina Mella, a senior lecturer in animal behavior and conservation at the Sydney School of Veterinary Science, told ABC News. However, there was no empirical evidence directly demonstrating a clear link between temperature and koala mortality.
Koalas are classified as “vulnerable” on the International Union for Conservation of Nature’s Red List of Threatened Species due to an estimated population decline of 28% over the last three generations.
Koala populations suffered enormous losses through direct mortality, injury, dehydration and long-term habitat destruction, but the latest research shows that even moderate heat can threaten the survival of the marsupial, the researchers said.
Combined with the increasing possibility of extreme weather events, these pressures create “compounding risks” for koalas, a species already vulnerable to habitat loss and fragmentation, Mella said.
The findings highlight that actions to improve heat-response strategies are necessary to protect vulnerable wildlife, the researchers said.