Entering a deep state of slumber sounds tempting on so many levels, but there are drawbacks to this period of hibernation, especially when your home is made of the stuff that swiftly crackles with flame.
That is the case for the eastern pygmy-possum (Cercartetus nanus) – a small, tree-dwelling marsupial with big, bald ears that scurries along branches in the dark of night on the southeast coast of Australia. During the day or while in hibernation, these night climbers curl up in tree hollows nested with bark and leaves.
These periods of deep slumber can last up to a month to only a few days (known as torpor), but as we know, a lot can happen in that time. Unlike many hibernators, eastern pygmy-possums enter bouts of shut-eye at anytime during the year and are not season specific. This puts these tiny creatures in danger from prescribed burns – a method of applying controlled fire to reduce the later risk of uncontrollable blazes.
“Increased habitat fragmentation, global warming, and other human activities have caused a rise in the frequency of wildfires worldwide,” wrote the authors in a study published in The Science of Nature. “To reduce the risks of uncontrollable fires, prescribed burns are generally conducted during the colder months of the year, a time when in many mammals torpor is expressed regularly.”
To determine whether these small marsupials can smell smoke while in torpor, a team led by Julia Nowack from the University of New England put five pygmy-possums to the test. As it turns out, the animals can sense fire danger from afar, but there's a catch: Waking up depends on the outside temperature.
At 10°C (50°F), the possums were still tightly curled in their hollows. At 15°C (59°F), three began moving, while the remaining two only lifted their heads. If their body temperature reached 24°C (75°F), they were agile and mobile.
The team's findings could have implications for seasonal burns in Australia, especially those during chilly winter days. As the researchers wrote: “...prescribed burns during winter should be avoided on very cold days to allow torpid animals enough time to respond.”