When a team of Australian researchers began testing the high-tech boxes they'd installed to save endangered greater bats in 2023, they weren't sure what they'd find. They hoped the arboreal marsupials would use them for nesting, replacing the tree cavities they typically nest in, but no one knew whether the creatures would survive.
So when Dr Keita Ashman, a threatened species and climate change adaptation ecologist at WWF-Australia, spotted a flying possum at the second site she'd marked, she was delighted.
«"I just burst into tears of surprise and joy," she told ABC News Australia.
A creature found nowhere else on Earth.
Greater gliders are nocturnal marsupials native to the old-growth forests of eastern Australia. They have large ears, fluffy fur, and long tails, and can glide up to 100 meters at a time. This species is found only in Australia.
«"I grew up watching great white squirrels all over the Dandenong Ranges, so they hold a special place in my heart," Dr. Ashman told the Australian National University.
Special nest boxes were designed and built through a partnership between the Australian National University (ANU), Greening Australia, and the World Wide Fund for Nature (WF-Australia) after the 2019-2020 bushfires destroyed a third of the remaining habitat of greater marsupial bats. According to ANU, the tree hollows that greater marsupial bats use for nesting can take over 100 years to form, so they can't simply find new trees to inhabit once their homes are destroyed.
Nest boxes typically used for wild animals are unsuitable for large marsupial possums, as the thin walls and lack of insulation can cause these birds to overheat. (According to the Australian National University, overheating slows feeding, which can be life-threatening.) The high-tech boxes in this project are insulated and have a non-toxic, heat-reflective, fire-resistant coating, ensuring the possums' safety.
The Goldilocks Box That Can Change Everything
«"I affectionately call this design the 'Goldilocks box' because we hope it will allow large flying squirrels to stay cool and cool, and will also help improve the species' resilience to climate change," Ashman said in July 2022.
«"The production and installation of high-quality birdhouses is an expensive process," added Australian National University research fellow Dr. Kara Youngentob, "so this project is important as it will help us understand whether expensive measures like installing birdhouses are the best use of funds in our urgent mission to save greater marsupial bats.".
And, as it turns out, gliders love them.
Their efforts appear to be bearing fruit. A 2025 study published in the journal Ecological Management & Restoration confirmed these hopes, showing that specially designed nest boxes for great marsupial squirrels were occupied at 100% within one year, with the squirrels occupying the new boxes an average of just 34 days after installation.
«"We didn't know whether these boxes were working or whether they were having an impact on the bat population," Dr. Yangentob told ABC News Australia. "To our great delight, the boxes were being used by the bats within a few months of installation, so we know the bats themselves like them and are using them.".
According to Yangentob, greater flying squirrels are Australia's largest marsupials and are critically endangered. More than 200 nest boxes have been installed in East Gippsland in Victoria and Tallaganda National Park in New South Wales. Yangentob told ABC News Australia that this project will help researchers learn more about how many individuals of this species remain in the wild.
This docile, nocturnal marsupial faces threats from climate change and deforestation, as well as the bushfires that devastated Australia in 2020. Its population has declined by 801 TP3T over the past 20 years, and the species is listed as critically endangered as of July 2022.
The Winter 2025 issue of WWF magazine featured an article about the Goldilocks Box program, confirming that the project is ongoing and expanding.
«"They are a treasure for this country," Dr. Yangentob told the Australian National University. "And I think the more people know about them, the more they will love them and want to protect them.".
This article was first published three years ago. It has been updated.
The article, titled "Ecologist Tears After Seeing Endangered Marsupial Squirrels Use New Nests," first appeared on Upworthy.