Mountain pygmy possum  (Burramys parvus)

Classified as Endangered (EN - B1+2abcde) on the IUCN Red List 2002 (1).

The mountain pygmy possum was only known from fossil records until it was discovered in the Australian Alps in 1966 (3). This small marsupial has fine dense fur, which is grey on the back and a creamy colour underneath (2). Males develop a more fawn-orange coat during the breeding season (2). The tail is prehensile and, at 14 cm, is longer than the body (2).

Found in two geographically isolated populations in south east Australia: one in the Mt. Bogong - Mt. Higginbotham range in Victoria and the other in Kosciuszko National Park, New South Wales (3).

Inhabits mountain summits at elevations between 1400 - 2200 m (2), where there are rock screes and boulderfields. This species is also usually associated with mountain plum-pine (Podocarpus lawrencei) heathland (4).

Living at high altitude, the mountain pygmy possum hibernates during the winter months from May to September. To survive hibernation these possums put on large amounts of fat and then roll into a ball to conserve heat. During the winter, individuals will occasionally rise from torpor to feed on stored seeds and berries (2). The mountain pygmy possum is the only marsupial to store food in a cache. 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 breed (2). As numbers of these moths decrease, the pygmy possum switches its diet to seeds and berries, prising open the hard cases with agile fingers (2).

Females occupy overlapping home ranges, whereas males disperse from their natal range and are more nomadic (2). Breeding coincides with the retreat of the snow line and the reappearance of Bogong moths in the region. Females give birth to 4 young, which are born in an immature stage of development (3). The young make their way to the pouch and attach to one of four teats (2), leaving the pouch after a few weeks to stay in a nest constructed from grasses (3). Young pygmy possums are independent after 9 weeks but females only have one litter a year due to the need to store up fat for winter hibernation (3). Mountain pygmy possums can live for as long as 12 years (2).

Due to the restrictions of their habitat requirements, mountain pygmy possums have suffered from the development of the ski industry in the Australian Alps (2). Although individuals may build nests around the foundations of lodges, development and the building of roads obstruct the dispersal of males. Habitat is also destroyed from the management of pistes and by general tourist development. A further threat to the mountain pygmy possum comes from habitat loss caused by increased temperatures and decreasing snow cover as a result of global warming (4).

Measures have been taken to decrease habitat fragmentation in ski resorts by protecting areas that are yet to be developed (2). In areas where possums and developments occur together, underground tunnels have been constructed to allow males to go about their nomadic lifestyle and therefore come into contact with mates. In Mouth Hotham the plight of male pygmy possums has captured local imagination and the tunnel has been dubbed the 'tunnel of love' (4). A captive breeding programme currently exists in Healesville Sanctuary (4), in order to provide a reservoir of animals for possible reintroduction.

• Hibernate: a winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
• Marsupial: a diverse group of mammals characterised by their reproduction. The embryo is born 11-35 days after conception. The tiny newborn crawls into the marsupium (pouch) and attaches to a teat where it stays for a variable amount of time. They also differ from placental mammals in their dentition.
• Natal: site of birth
• Prehensile: capable of grasping.
• Torpor: a sleep-like state in which the body processes slow to a fraction of their normal rate.

1. IUCN Red List (October, 2002) http://www.redlist.org
2. Animal Diversity Web (June, 2002) http://animaldiversity.ummz.umich.edu/accounts/burramys/b._parvus$narrative.html
3. Animal Info (June, 2002) http://www.animalinfo.org/species/burrparv.htm
4. Melbourne Zoo (June, 2002) http://www.zoo.org.au/conservation/MpygmyPossum.htm