The Norwegian Lemming is a common species of Lemming found in Northern Fennoscandia. It is the only vertebrate species endemic to the region. The Norway Lemming dwells in tundra and fells, and prefers to live near water. Adults feed primarily on sedges, grasses and moss. They are active both during the day and night, alternating naps with periods of activity. The Norwegian Lemming has a dramatic three- to four-year population cycle, in which the species' population periodically rises to unsustainable levels, leading to high mortality, which causes the population to decrease drastically again. The Norway Lemming spends the winter in nests under the snow. When the spring begins and the snow starts to thaws, they must migrate to higher ground, where the snow is still firm enough for safety, or, more commonly, to lower ground, where they spend the summer months.
From album: Norwegian Landscapes and biodiversity