Possums in Australia are struggling with extreme heat conditions

As Australia's temperatures continue to get hotter, the specialized fur that possums evolved to save energy is now putting them at risk of overheating.

possum (Myrmecobius fasciatus) is an unusual marsupial in that it is active during the day, feeding on termites hidden under tree logs and topsoil. Because these insects are low-calorie foods, possums, which typically weigh about 500 grams, have evolved fur that absorbs heat from the sun, saving calories spent on generating body heat.

As temperatures rise, that evolutionary trait can backfire, causing possums to overheat within minutes of feeding in direct sunlight. kristin cooper at Curtin University, Perth, Australia.

Quolls once roamed southern Australia, but over the past two centuries they have fallen prey to cats and foxes introduced by European settlers. Currently, these endangered animals are concentrated in just two small nature reserves in Western Australia.

To increase their numbers, conservation groups are gradually moving the marsupials to areas protected from their native predators. But global warming is making some of these regions even hotter and drier.

“Environmental change is occurring at an unprecedented rate due to anthropogenic global warming, which means that predicting future species distribution and population patterns, protecting and managing them requires environmental conditions “This means it is important to understand the ecological consequences of changes in philip withers researchers from the University of Western Australia write in a paper.

To learn more, the pair used a thermal imaging camera to film 50 wild animals eating termites at different times of the day from 2020 to 2021.

At each site, portable weather stations were used to record factors such as temperature, wind speed, and humidity. They then incorporated this data into a computer program to model how environmental conditions affected the quolls' internal temperatures.

The researchers found that on days of high heat stress, such as in dry environments with temperatures of 40 degrees Celsius, possums overheat within 10 minutes of exposure to direct sunlight. After that, they need to stop eating and hide from the sun until their body temperature drops.

Shade is helpful, but shade is often scarce, and seeking shade limits the termite-hunting territory of possums, Cooper says. The model also suggests that the combination of high outdoor temperatures and radiant heat from the ground can cause possums to overheat even in the shade.

Feeding at night is not an option for possums, as they have poor night vision and lack the strength to invade termite mounds at night.

To overcome these problems, Cooper recommends conservation groups move quolls to cooler areas of their territory and provide plenty of shade.