Pygmy Possums: Burramyidae

Pygmy possums are nocturnal, which means that they sleep during the day and are active at night, although a few species may come out on cloudy days. All but one species live in trees and are good climbers, using their prehensile (grasping) tail to help them climb. These tree-dwelling pygmy possums build nests inside tree hollows using leaves and other plant material. As many as five possums live in a shared nest.

The female pygmy possum has four teats, or nipples. This is the maximum number of young that she can raise, although the usual number is one to three young, once or twice a year. She raises the young without any help from the male. After birth, she carries the young in her pouch until they reach an appropriate size, around 0.2 ounces (7 grams). They then spend time in the nest until they reach about 0.35 ounces (10 grams), after which they become independent. Although not much is known about how long some species live, female mountain pygmy possums live about eleven years, while males live only four, an unusually large difference in lifespan.

The mountain pygmy possum lives in mountain meadows and rock fields. It is very different from other pygmy possums. It lives at high elevations between 4,265 and 7,300 feet (1,300 and 2,230 meters), where there is snow on the ground at least three months out of the year. It shares a nest with other possums of the same sex, and stores up fat to survive the winter. One individual was found in autumn that weighed almost three times its normal weight. In the winter, the mountain pygmy possum can reduce its heart rate, energy use, and body temperature and remain inactive for up to twenty days at a time.