{"id":696812,"date":"2026-05-27T01:03:17","date_gmt":"2026-05-27T01:03:17","guid":{"rendered":"https:\/\/www.newsbeep.com\/au\/696812\/"},"modified":"2026-05-27T01:03:17","modified_gmt":"2026-05-27T01:03:17","slug":"koalas-at-risk-of-death-once-seven-day-temperatures-rise-beyond-27c","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/au\/696812\/","title":{"rendered":"Koalas at risk of death once seven-day temperatures rise beyond 27C"},"content":{"rendered":"

Extreme heat is a major factor in the number of deaths and hospitalisations of Australians every year.<\/p>\n

A new study in Biology Letters<\/a> suggests koalas (Phascolarctos cinereus) have faced the exact same problem when there is a seemingly moderate temperature increase.<\/p>\n

The researchers found the risk of admissions and death climbed for the furry marsupials when the seven-day average temperature maximum hit 27 degrees Celsius or higher.<\/p>\n

This was calculated by comparing the case notes for 11,862 koala hospitalisations in NSW with weather records from 2000 to 2022.<\/p>\n

Koala hospitalisations or death were 1.5 to 3.5 times more likely in seven-day periods where average temperatures were above 30C in their home ranges (compared to a 25C baseline).<\/p>\n

Valentina Mella, a behavioural ecologist from the University of Sydney who led the study, said the connection between hospitalisations and temperature thresholds was “scary”.<\/p>\n

“We found that all the koalas in inland NSW were the ones exposed the most to these high temperatures because it’s just hotter there,” she said.<\/p>\n

\"A<\/p>\n

Valentina Mella has undertaken several studies of koalas in the north-west of NSW. (Supplied: University of Sydney)<\/p>\n

Dr Mella said longer periods of hot weather and drought from climate change, coupled with other factors like habitat fragmentation and disease, could drive local extinctions in the north-west NSW.<\/p>\n

“These are the first populations that are going to go,” she said.<\/p>\n

“And in fact, we have already seen this because the population in Gunnedah is now functionally extinct.<\/p>\n

“The remaining animals are infertile. Once they die, there’s going to be no new animals to take their place.”<\/p>\n

\"A<\/p>\n

Areas with the greatest number of weeks above 30C have higher risks of koala hospitalisations or deaths. (Biology Letters: University of Sydney, CC BY 4.0<\/a>)<\/p>\n

Natalie Briscoe, a University of Melbourne ecologist who was not involved in the study, said it was difficult to capture climate or weather impacts on animal survival with the exception of mass die-offs like what occurs with flying foxes.<\/p>\n

“Using koala admissions into care in this way is a neat approach to capture this association,” Dr Briscoe said.<\/p>\n

“The findings align with what we know. We have good reasons for expecting hotter temperatures to have a negative impact on koalas based on their physiology, diet and behaviour and past studies documenting responses of individual populations to extreme heat.<\/p>\n

“Unfortunately, things are likely only going to get worse for koalas under climate change, and particularly those in northern and inland areas.”<\/p>\n

How do koalas cope with the heat?<\/p>\n

Koalas have a range of strategies to deal with hot weather.<\/p>\n

“They can preserve water by producing really concentrated urine,” Dr Mella said.<\/p>\n

“They can reabsorb the water from the colon, producing really, really dry pellets or scats.<\/p>\n

“And they can have behavioural strategies like tree hugging to try to dissipate the heat against the cooler tree trunks.”<\/p>\n

\"A<\/p>\n

A koala rests low to the ground in the shade to try beat the heat. The species is considered endangered in NSW, Qld and ACT. (Supplied: University of Sydney)<\/p>\n

The main way koalas keep cool is panting like a dog.<\/p>\n

Panting results in a loss of water, which can be a problem in a drought.<\/p>\n

Dr Mella said in north-west NSW when temperatures hit 30C, koalas became severely dehydrated and were seen sitting at the base of trees.<\/p>\n

Koalas typically draw their water needs from the eucalyptus leaves they eat.<\/p>\n

But Dr Mella said trees reabsorbed moisture from their leaves when it didn’t rain.<\/p>\n

“And then for these animals it’s like chewing cardboard, really,” she said.<\/p>\n

Kara Youngentob, a landscape and nutritional ecologist at the Australian National University who was not involved in the study, said koalas also lost their appetite when they got hot, which could be a problem even with low temperature rises.<\/p>\n

“We [humans] can go two weeks or more without eating, as long as we have water,” Dr Youngentob said.<\/p>\n

“Koalas can only last a few days; they basically have no fat reserves and they have to eat every night.”<\/p>\n

Dr Youngentob said koalas lived in a pretty fine nutrient balance because they had to process toxic eucalyptus leaves for little reward.<\/p>\n

“They need to meet a balance of energy and protein in a diet that has very little energy and protein,” she said.<\/p>\n

What can be done to help koalas?<\/p>\n

Dr Mella said water stations could be left out as well as shade structures built for koalas in hot regions like north-west NSW.<\/p>\n

“We do that for cattle and we do that for animals that we use for our needs, so we really should be doing it for wildlife as well,” she said.<\/p>\n

Other researchers such as Dr Youngentob are trying to breed eucalypts with high protein and less toxins for koalas.<\/p>\n

“The concept we have is nutritional refugia, having climate refugia with habitat where koalas can survive and they don’t have to eat as much to survive.”<\/p>\n

\"Two<\/p>\n

Kara Youngentob and Christina Zdenek from ANU are planting saplings as part of a project to nurture food trees that are more nutritious for Redlands Coast koalas in Qld. (Supplied: Kara Youngentob)<\/p>\n

But koalas need more than trees with their favourite food to survive.<\/p>\n

Bill Ellis, a University of Queensland ecologist who was not involved in the study, said non-food trees were just as vital to the survival of the species as food trees.<\/p>\n

“They can’t survive without the shady trees that they sit in during the day,” he said.<\/p>\n

“When it gets hot, they will find cooler parts of their home range and cooler trees and they hop in those trees.”<\/p>\n

Dr Ellis said it was important for private properties to retain patches of bush, especially along creek lines.<\/p>\n

“What we really need to do is incentivise that kind of behaviour and also inform [land owners] about what’s going to work,” he said.<\/p>\n","protected":false},"excerpt":{"rendered":"Extreme heat is a major factor in the number of deaths and hospitalisations of Australians every year. A…\n","protected":false},"author":2,"featured_media":696813,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[64,63,339701,339700,339698,339708,339699,50155,339705,339704,128,339707,339706,339702,339703,338],"class_list":["post-696812","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-au","tag-australia","tag-dead-koala","tag-do-koalas-get-heat-stress","tag-hot-koala","tag-how-do-koalas-cool-down","tag-how-hot-can-koalas-get","tag-koala","tag-koalas-and-climate-change","tag-koalas-under-threat","tag-science","tag-what-do-koalas-eat","tag-what-is-climate-change-doing-to-koalas","tag-whats-killing-koalas","tag-why-are-koalas-endangered","tag-wildlife"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/696812","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=696812"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/696812\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/696813"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=696812"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=696812"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=696812"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}