The Mountain Pygmy-possum is mainly grey-brown with paler grey/brown to cream underneath. Its fur is fine but very dense keeping the animal warm in sometimes freezing temperatures. It has a darker ring of fur around its eyes, rounded ears and a long tail. The Mountain Pygmy-possum is part of the Pygmy-possum family and the largest. With males only growing to 110mm and a weight of 55g and females slightly larger growing to 111mm and a weight of up to 80g this possum is sometimes mistaken for a rodent.
The Mountain Pygmy-possum is the only Australian mammal whose distribution is limited to alpine and sub-alpine regions where there is a continuous period of snow cover for up to six months. They exist in two national parks; the Kosciuszko National Park and Alpine National Park in Victoria. Ideal or high quality habitat for these possums includes deep boulder fields with high elevations, high availability of the Bogong Moth and another food source such as seeds nearby. These factors influence hibernation, food availability, nesting and survival.
The fossil record suggests that the areas of occurrence are decreasing due to the receding snowline. The total area of occupancy of this species is thought to be less than 7 km².
Mountain Pygmy-possums feed primarily on the Bogong Moth. This moth is rich in protein and crucial to the possums gaining sufficient fat reserves for winter and hibernation. Other insects will be consumed which include caterpillars, spiders and beetles. Seeds to native flora species will also be eaten.
The possums prepare for hibernation after breeding takes place with the body weight doubling before winter begins. Hibernation can last between 5 – 7 months. If there is not enough food available in the months leading up to winter Mountain Pygmy-possums can starve.
Spherical nests are built with approximately 20cm diameters. The nests observed have been made of mostly moss. Females stay in the boulder fields where there is high food availability while the males disperse after breeding. The females will stay so that there is enough food for the growing young. Only females and their young are live in the nests during this time with males being pushed out meaning males are more vulnerable to predation. During autumn both sexes are increasing their time in the nests and by the start of winter 70% of their time is spent in the nest. The breeding season includes mating, gestation and nesting and occurs from October to December with young dispersing up to April.
Usually females have a single litter but if that litter is lost early enough the female can give birth to another litter. There are usually three to four babies born in a litter. These young possums live in the pouch for four to five weeks and then a further five weeks in the nest where their mother will continue to suckle them. The joeys are weaned at around ten weeks. The joeys will grow and can breed at one year of age however continue to grow until they are fully grown at about two years of age.
Conservation Status: Critically Endangered
Their threats are: habitat destruction and degradation, climate change (increased temperatures), development and increased snow sports, predation by feral animals (cats, foxes), exotic species (plants and animals), litter/garbage (encourages cats and foxes to these areas), rat traps/poison, threats to the Bogong Moth (without it they would not survive so any threat to this moth threatens the Mountain Pygmy possum’s survival).