Moving home because the fossils say so

Chasing the heat to avoid the impact of climate change may seem counter-intuitive, but it could help save Australia’s mountain pygmy-possum (Burramys parvus).

Researchers led by the University of NSW (UNSW) have started moving some of the diminutive marsupials from their “traditional” alpine/subalpine habitat to a lower and warmer rainforest environment where, in theory, they won’t need to hibernate in winter.

They are one of the few animals in Australia that do.

Hibernation becomes a problem if increasing temperatures mean there isn’t enough snow to provide the cover and thus the insulation the possums need while they are buried deep within humid rock piles. If it gets too cold, they may wake up and shiver to death.

“You just need two bad winters like this, and the species could collapse,” says Hayley Bates, co-author of a paper published in the journal Philosophical Transactions B.

 But why would relocating them work? 

Because, says palaeontologist Mike Archer, the paper’s lead author , there’s evidence that B. parvus doesn’t need to be up in the mountains in the first place.

“The fossil record for all other species in the genus Burramys indicates that their current habitat is a far cry from their comfort zone for the last 25 million years,” he says. “All previous populations thrived in cool temperate lowland rainforest communities – not the alpine one.”

Archer suspects the mountain pygmy-possum, which was only discovered as a living animal in 1966, has been marooned in a less-than-ideal environment where it has been forced to use strategies such as hibernation to survive.

“What probably happened is that the modern species followed cool rainforest which invaded the alpine areas during a period of relatively warmer, lush conditions,” he says.

“After these conditions deteriorated with further climate change, they were stranded in an environment that was at the extreme end of their adaptability.”

With support from Australian and international environmental groups, a team from UNSW, University of Sydney and University of New England has moved two breeding pairs to Secret Creek Sanctuary at Lithgow, where they are being maintained at temperatures that would have suited their ancestral species. The aim is to establish an initial colony of 25.

The bigger picture issue, Archer says, is the value in paying more attention to fossil evidence when developing conservation strategies.

“While it’s been traditional to assume that ecologists have the best understanding about the needs of endangered creatures to survive, in reality many animals and plants have a wider adaptive resilience than their current situations might suggest,” he says.

“This is where the fossil record comes in. It’s not unusual for endangered species to be occupying the ‘extreme’ edges of a once much wider habitat. Giant pandas, for example, were once widespread over lowland areas but, because of agriculture, have long since been confined to mountainous areas.

“Understanding former distributions, even way back in time, can provide new insights into translocation strategies that might work for species otherwise threatened in the extreme edges of their once much wider distribution.”

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