Norway lemming

The Norway lemming, sometimes referred to as the Norwegian lemming, is a distinctive small mammal found exclusively in northern Fennoscandia. It is the only vertebrate species endemic to this region. These lemmings thrive in the tundra and fells, especially in areas close to water, where they feed on sedges, grasses, and moss. They are consistently active throughout the day, taking occasional breaks for rest.

These lemmings are easily recognizable by their striking black and yellow-brown fur, each sporting a unique pattern. They grow to about 155 mm in length, with short tails measuring between 10-19 mm, and they can weigh up to 130 grams. Their teeth are quite specialized, with a dental formula of 1/1, 0/0, 3/3.

One of the most fascinating aspects of Norway lemmings is their population cycle, which fluctuates significantly every three to four years. Their numbers can rapidly increase, followed by a dramatic decline due to high mortality rates. During winter, they nest under the snow and migrate to different elevations as the snow melts in spring, coordinating their movements for survival.

Under favorable conditions, their populations can surge. They mature rapidly and produce many offspring. However, these lemmings are solitary creatures; the stronger individuals will expel the weaker ones to avoid resource depletion. In stressful situations, they may scatter in all directions. Contrary to popular myths, they do not deliberately march into the sea, but they do migrate.

Genetic studies suggest that Norway lemmings survived the ice ages in ice-free refuges in Western Europe. Some researchers even theorize that they might be descendants of the brown lemming, having moved into the region after the glaciers receded.

Regarding predators, Norway lemmings are known for their boldness. They have been observed to confront predators or intruders, including humans, rather than flee. Their audacious behavior and vivid coloration suggest that they might be an aposematic species, meaning their appearance serves as a warning to potential predators to stay away.