The Norway lemming is one of the largest lemmings around the globe. This migratory rodent is quite common in the tundras of Scandinavia and Western Russia. Individuals of both sexes exhibit similar size and color. The Norway lemming has a thick body. The fur is heavy, helping the animal keep warm during the cold winter months. Lemmings display the same coloration year-round - black and brown with golden-yellow bands. There is no information on the life expectancy of this species in the wild. However, the oldest recorded Norway lemming has lived for 3.3 years in captivity. In addition, other closely related lemmings typically live for 1 - 2 years.
This species is distributed throughout a region called Fennoscandia. It begins form the Russian Kola Peninsula, reaching the west coast of Norway as well as from the northern coast of Norway southwards to the Baltic Sea. Where the Norway lemmings are in abundance, they often migrate south. The ideal habitat of these rodents is tundra and alpine areas. Their winter habitat is usually secluded sites, covered with snow. When there is no snow, they prefer living in different moist environments such as bogs or marshes. They are also known to favor heathland habitat, dominated by dwarf shrubs.
Norway lemmings may be active at any time of the day. Overall, they are usually active for an average of 6 hours per day, during which time they mainly roam and look for food. These rodents tend to be solitary, coming into serious conflicts with each other in overcrowded territories. In these over-populated areas space and food are often in shortage, and the animals disperse to live independently. Males of this species exhibit boxing, wrestling, and threatening behavior. The communication and perception behavior of this species is insufficiently explored, although related lemming species are known to rely on scent, through which they mark their home ranges. In addition, most lemming species are able to recognize conspecifics by scent.
There is no information about the mating system of Norway lemmings. However, considering characteristics of other lemmings and the independent nature of Norway lemmings, they are unlikely to be monogamous and may exhibit either polygynous or polygynandrous (promiscuous) mating systems (where both males and females may have multiple mates). Breeding occurs throughout the year. Females of this species are very productive, able to yield a litter every 3 - 4 weeks. Gestation period typically lasts for 16 - 23 days, producing 14 - 16 babies. The age of sexual maturity is 1 month old for males and 3 weeks old for females. However, there has been recorded a 2 week old pregnant female.
Currently, there aren’t any serious threats to the population of this species as a whole, although possible threats include environmental changes as well as habitat degradation as a result of grazing by other herbivorous species.
According to IUCN, the Norway lemming is generally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) and its numbers are stable.
In overcrowded areas, especially in tundra, where up to 134 lemmings sometimes share a single acre of land, these animals totally destruct the local vegetation. As a result, the area may take as long as 4 years to completely recover. Despite this terrible damage to the land, population peaks of the Norway lemmings are very beneficial for numerous predators of their range (Arctic foxes, red foxes, snowy owls).