It is found only in the
Arctic biomes in the
Russian Federation, and it is the most common mammal on
Severnaya Zemlya. Specimens were once found in England, but they are now
extirpated. For the most part, lemmings of the genus
Lemmus can coexist with those of genus
Dicrostonyx. Arctic lemmings migrate when population density becomes too great, and they resort to swimming in search of a new habitat. The disappearance of lemmings and the lemming cycles in the Arctic have shown that they are the causes of fluctuations in local breeding among geese and waders. Recovery of lemmings after years of low density is associated with a period of successful breeding and maintenance of their young in the snow. The diet of the Arctic lemming has been studied, and it has been found to consist of 86% dicotyledons, 14% monocotyledons, and less than 1% mosses. The diet of a family of lemmings consists mostly of
Saliceae, although
Poaceae are also in their diet. They are a well studied example of a cyclic predator−prey relationship. Terns in the Arctic target lemmings that move in groups; after attacks, lemmings seek shelter in holes or elsewhere out of the terns' territory to avoid additional attacks. ==Environment==