North American Brown Lemming - Colonies

Colonies

They live underground, in colonies, and may produce up to three litters each year, including under the snow in winter. With a gestation period of 23 days, the female will give birth from four to nine young. The brown lemming is not migratory and when overpopulated (and during mating season), they will fight amongst themselves. Bylot Island has several wetlands with shallow polygons and many types of mosses, grasses and sedges, which suits the North American brown lemming very well for several reasons (Rochefort et al. 1996). On Bylot Island they prefer to live in the South plain of the island and mostly live in the polygon fen, also known as wetlands, which mostly supports the graminoids that they rely on for food (Bety et al. 2002). During winter brown lemmings live in insulated burrows in the ground made out of sedges and grasses (Reid et al. 2011). They make their nests in these confined burrows underground because it increases insulation and allows them the to reproduce during winter (Duchesne et al. 2011). Studies on Bylot Island have shown that brown lemmings prefer to burrow under increasing snow depth rather than more dense. They believe that brown lemmings do this because the more snow depth the better energy is trapped and the number of nests increased. Deeper snow cover also protected lemmings and their nests from avian predators; mammalian predators can still forage for them but since their nests are so deep it decreases the of some predators ability to see, therefore, they are very well protected from predators (Duchesne et al. 2011; Reid et al. 2012). During summer, brown lemmings do not have the cover of snow and their territories become a lot more widespread across Bylot Island (Reid et al. 2012).