Fossils clues may save endangered marsupial

By John Pickrell 7 October 2010
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An innovative new project is using evidence from the fossil record to help save the mountain pygmy possum from climate change.

ONE OF AUSTRALIA’S MOST imperilled animals is the mountain pygmy possum. It is found in just a few isolated alpine patches of NSW and Victoria, which are shrinking annually through climate change.

Ian Pulsford of the NSW Department of Environment, Climate Change and Water (DECCW ) says that this animal already survives at the top of the region’s elevation range, so there simply isn’t anywhere for it to go as warming destroys its alpine habitat.

Conventional captive breeding efforts have focussed on producing animals to be re-released into the ever-shrinking patches of alpine habitat. But a bold and potentially controversial new plan has been developed by a team of researchers led by Professor Mike Archer at the University of New South Wales in Sydney.

The project – which ultimately seeks to introduce the species to areas outside of its known range –  is detailed in Australian Geographic #100 and was announced at the AG Society Awards dinner in Sydney.  

“It needs funding, but it could be the most exciting project of this kind in the world in terms of an innovative way to counter the unquestioned threat to the survival of a species through climate change,” says Mike.

Mountain pygmy possum the only hibernating marsupial

This possum – with the taxonomic name Burramys parvus – is the world’s only hibernating marsupial and inhabits the high alpine boulder fields of NSW and Victoria. It is already threatened by feral cats, foxes, development and shrinking supplies of Bogong moths – one of its major food sources.

But now it faces a new threat as the snow cover it needs for insulation during hibernation is reduced annually. “We estimate there are less than 2000 adults left,” says Linda Broome, an alpine ecologist with the DECCW. “The impact of current threats…is predicted to increase with loss of snow cover from global warming.”

In what Mike describes as a “delicious irony”, the species was only known in fossil form until 1966, when visitors to a Mount Hotham ski lodge spied a weird little animal running around a kitchen. “Then, almost immediately after we discover it’s alive, in comes climate change,” says Mike. “That’s going to put the temperature up at least one degree…[enough] to destroy the habitat. It’s a very beautiful and wonderful animal that’s going to get knocked by the slightest shift.”

The situation seems desperate, but by taking clues from the fossil record into account, Mike’s team offers hope. During the past 24 million years, close relatives of the mountain pygmy possum have been common throughout Australia’s lowland rainforests.

“Everywhere we’ve found fossils of these species of miniature possums it’s always been in lowland rainforest – in Central Australia and the Simpson Desert it was there in scrubby lowland rainforest. In Riversleigh [fossil fields in Queensland], spanning between 24 million and 12 million years ago, Burramys is found all through lowland rainforests in rocky limestone habitat.”

Plan to re-introduce mountain pygmy possums

Mike is convinced the pygmy possum tracked rainforest up the mountain in a previous bout of climate change and became trapped up there in the boulder fields when the rainforests disappeared. His idea is to try to re-establish a colony in an area of lowland rainforest, abundant in NSW and Victoria. 

Mike thinks that because of its evolutionary heritage in lowland rainforests, the pygmy possum already has the capacity to thrive in warmer conditions, and this is what he wants to test. “We really have to aggressively get over our conservatism, because it’s at the tremendous expense of the survival of species,” he says. “It’s clear that conventional conservation is not working and not lasting.”

He has been working with an existing captive-breeding program that uses artificially cooled enclosures at Victoria’s Healesville Sanctuary. But his plan is to try breeding the animals at ambient temperatures and then release them into a large outdoor enclosure at Secret Creek Sanctuary in Lithgow, NSW. Further down the line, if the breeding program is successful, the idea is to release them into lowland rainforests.

“My guess is that Burramys will find any number of things to eat because they’ve always been in lowland rainforest. It’s filled with resources that evolutionarily they are suited to eat,” says Mike. “They are not going to damage other species in those rainforests because they’ve always been there. They are missing – a poltergeist, if you like; they were there and they should be there.”

Remaining obstacles include getting legislative approval from parks authorities and finding sponsors to cover the costs of the breeding facilities and enclosures.

“Mike’s proposal is certainly a bold and innovative idea and DECCW is exploring it with him,” says Linda Broome. “The prerequisites will be to establish an effective captive-breeding program [at cold temperatures] for the Kosciuszko population. This is needed not only to provide the animals for the experiment but also to provide an insurance policy against sudden catastrophic wild declines; they’ll also need to demonstrate that Burramys can breed in lowland rainforest conditions.”

Trevor Evans, of Secret Creek Sanctuary, says that current systems of saving endangered species need to be addressed, and thinks that Mike’s left-field suggestion is a step in the right direction.

“More and more of Australia’s wildlife is disappearing and we seem to have a sad habit of changing laws and management practices after a species has gone,” Trevor says. “It’s better that we try [Mike’s] method now, than wish we had in 10 years time. Like the Tasmanian tiger, we will not fully appreciate the species until we lose it, which is a real possibility.”

This story is an extract of a longer feature found in Australian Geographic #100.