The Mountain Pygmy-possum lives only in alpine and subalpine areas on the highest mountains of Victoria and NSW. The total population has grown in the last few years but it is still less than one thousand. Adults average 40g (less than one and a half ounces for US folk) but vary from 30 grams in spring up to 80 grams in autumn when they fatten for winter hibernation. They are our only hibernating marsupial and the only Australian mammal to be entirely restricted to the alpine zone above the winter snowline; it is dependent on the insulation provided by snow for its survival.

You say it looks like a mouse? Well, it’s a little larger in size, its tail is part furry and coiled, it has 5 (not 4) front toes, and joined (syndactyl) second and third back toes.

The MPP lives on the ground in rocky areas where boulders have accumulated below mountain peaks. It survives winter by fattening in late summer and autumn and hibernating for up to seven months, from autumn until the snow melts in spring. Seventy percent of the diet is invertebrates such as the migratory Bogong Moth, caterpillars, beetles, spiders and millipedes; the remainder comprises fruits and seeds.

One litter of four young are produced in spring; young are independent by late summer; breeds when one year old; average longevity is two to three years but females may live up to thirteen years and males five years.

This is the latest video I’ve found of the MPP. There are others but they are older so some of the figures given are not up to date. The video shows that recently MPPs have been studied and bred in a sanctuary with the hope of keeping them from extinction. https://www.msn.com/en-us/video/animals/dozen-critically-endangered-mountain-pygmy-possums-successfully-bred/vi-AA1YOTSn