Multi-coloured norwegian lemming - about 10 cm long (without tail) - is very well hidden into fjeldvegetation.
Lemmings belong in the family of cricetid rats, mice and voles. In Finland we have two lemming species: Norway lemming and wood lemming. Norway lemming (Lemmus lemmus) lives in the fell areas. It is distributed only in to Fennoscandia; it is endemic here. In other northern areas there are other lemming species.
In the summer Norway lemming is lower in the fells, near brooks and in the marshes eating mainly hay, grasses and dwarf shrubs. In the winter they live under thick snow cover for example in the snow beds of fell fields eating mainly only mosses (Polytrichum, Dicranum). This migration after year seasons happens every year.
Sometimes this spring and autumn migration turns into long mass migration. If the amount of lemmings grows very much, there isnt enough of food anymore and they have to go elsewhere to find food. The topography leads migrating lemmings in to same paths and thats how those huge herds originate. Naturally the lemming hardly is a herd animal. Sometimes the migrations can reach the southern border of the province of Lappi. The last big migrations were in the seventies, so there is one big to come in the near future.
Norway lemming reproduces several times in a year and at one time it gives birth to 5 - 7 cubs. In good conditions it can reproduce also in the winter. Because of the thick and long lasting snow beds in the many fells (especially in Norway Hardangervidda) lemmings reproduce there in the winter regularly than in our Lapland where there are less snow beds.
Norway lemmings - like many other small mammals - are important food for many predators (for example for rough-legged buzzard).