Unlike most possums, the mountain pygmy-possum is mainly terrestrial, although it is also an adept climber. Living at high altitude, the mountain pygmy-possum hibernates during the winter months from March / April to September / October. To survive hibernation these possums put on large amounts of fat and then roll into a ball to conserve heat, while snow cover also provides important insulation. During the winter, like all hibernators, individuals regularly arouse for short periods from torpor, and will occasionally move to more suitable hibernacula sites. The mountain pygmy-possum stores seeds in caches in captivity, but does not appear to feed during the winter hibernation period in the wild (5). Possums are nocturnal and during the 'active season', which runs from October to April, will feed primarily on the high energy Bogong moth (Agrotis infusa), which arrives in the Australian Alps in large numbers in the summer months to aestivate in the cool rock crevices of the boulderfields. As numbers of these moths decrease in the late summer and autumn, the pygmy-possum switches its diet to seeds and berries, cracking open the hard cases with its large, specialised premolar tooth (1) (2) (3) (4).