The next stamp of the stamp series of Estonian fauna features the northern birch mouse (Sicista betulina Pallas, 1779). The northern birch mouse is a smaller mouse sized rodent belonging to the family of the Dipodidae. Its characteristics are a black stripe on the back and a tail much longer than its body. The northern birch mouse is an omnivore that eats both fruits and seeds as well as insects and caterpillars of butterflies. It hibernates from September to May. When waking up in spring, the animals weigh only about 8 grams, however, by autumn, they store plenty of fat, weighing nearly 15 grams then. They breed once a year and usually 4-6 young are born per litter. The northern birch mice prefer thick and high vegetation areas in forests, meadows, and around old farms as their habitat. They often climb on higher herbaceous plants and bushes. The northern birch mouse occurs in the forest zone from Norway, Denmark, and Austria to Lake Baikal, but they are rarely seen in all those places. In Estonia, the northern birch mouse occurs on the mainland only. As a rare and little researched species, the northern birch mouse has been added to Annex V of the Habitats Directive of the European Union, and in the list of species protected under Category III in Estonia.