Possum magic

For around a century the possum Trichosurus cunninghami, found in mountain forests north of Melbourne, was best known for keeping the heads of well-to-do Londoners warm.

The possum was extensively hunted for its superbly soft pelt, with most sent to milliners in Britain, but dwindling numbers led to a possum cull ban in the 1960s.

Despite the pelt moratorium, very little was known about this shy, mountain marsupial until an ANU science graduate took an interest in possums in the early 1980s.

Ecologist Professor David Lindenmayer (pictured, left, with Associate Professor Cunningham)  began studying possums in the area around Marysville in 1983, becoming the world’s leading expert on one of Victoria’s faunal emblems, Leadbeater’s possum, and making significant recommendations which have been adopted to help ensure the survival of the species.

In 1990, he began studying the mountain brushtail possum and after 13 years of analysis with statistician colleague Associate Professor Ross Cunningham, they have discovered a host of new insights into the biology and ecology of the species.

In what has become Australia’s longest possum study, Professor Lindenmayer and Associate Professor Cunningham are also revealing the reasons why the mountain brushtail has recovered so well in the 40 years since culling was prohibited.

“Up until this study, there was very little long-term information on this possum — factors such as population, demographics and habitat — which is extremely important information for the long-term protection of species which in the past have been hunted to within an inch of extinction,” Professor Lindenmayer says.

About 230 individual possums in a 35-hectare stand of ancient mountain ash trees in the central Victorian highlands have been microchipped as part of the study, identifying each possum with a serial number.

Over time, long-term trends in the population can be extrapolated and the effect of variables, such as fire or logging, on the possums can be measured.

“All this builds a comprehensive picture of the biology, ecology, and population dynamics of these possums. Our preliminary findings reveal new information on the mating system and the dispersal ability of the species — for example, it seems that old growth patches are an important source of dispersing possums to surrounding, less productive, regrowth stands of Mountain Ash forest.”

Professor Lindenmayer and Associate Professor Cunningham had long suspected that the mountain brushtail possum had a secret and the most surprising finding of this study was the discovery that the possum, which was thought to live in mountain areas right up the east coast to Queensland, was actually two different species.

Their research had borne out differences among brushtail possum populations throughout the distribution of the species ­— from Melbourne to Gladstone in central Queensland. Southern mountain brushtails had consistently longer ears, tail and feet than their northern cousins. Although a new species of possum had not been found since 1945, in 2002 genetic tests confirmed the field findings of Professor Lindenmayer and Associate Professor Cunningham.

The southern mountain brushtail possum species was declared Trichosurus cunninghami, a tribute to Associate Professor Cunningham’s years of number crunching and modeling the differences between species, and his significant contribution to the ecological and conservation sciences over the past two decades. The southern species retained the common name mountain brushtail possum, while its northern cousin became known as the short-eared possum (and kept the original genus name Trichosurus caninus).