Healesville Sanctuary’s tiny Mountain Pygmy Possums are settling down this week for the most epic nap in Australia: a winter hibernation that sees the teacup-sized marsupials double – then halve – their bodyweight.
The critically endangered possums are the only marsupials in the world to hibernate. Adapted to spend winter months in nests under snow cover among Victoria’s mountain boulder fields, they lower their body temperature to around 2°C and live off stored fat reserves.
The possums bulk up to a whopping 70-80 grams throughout autumn but will slim down to about 40 grams once they get active again at the start of October.
Healesville Sanctuary keeper Paula Watson said this is her favourite time of the year.“I love this time of year, they’re always super adorable,” Ms Watson said. “We weigh them once a week and the possums are just tiny, curled up balls of pudgy cuteness.”
The possums will spend most of winter in the extremely energy efficient state called “torpor”.
“They’re not really asleep,” said Ms Watson. “Their respiration slows right down, their heart rate slows, and they drop their body temperature right down to ambient temperatures.”
Ms Watson said the possums do wake up during hibernation, but not for long. “Each torpor period might last for a week, or a couple of weeks, then they wake up, have a drink, eat a seed, have a poo, then they go back into the torpor,” she said.
“When they’re in torpor they actually feel cold to the touch. They feel like they’re 2C.”
Fourteen Mountain Pygmy Possums – seven males and seven females – are hibernating in a temperature-
controlled environment at the Sanctuary that mimics their natural habitat, complete with fake snow.
Mountain Pygmy Possums are critically endangered, and are threatened by habitat loss, climate change
and introduced predators in the wild. Zoos Victoria’s Mountain Pygmy Possum breeding program is part of
their Fighting Extinction initiative.