tend to be larger than females. On average these animals are about 20–27 cm in total length (including the tail), with tails 6–10 cm long, and weigh 125-178 grams. The water vole is the second largest arvicoline in its range (after the muskrat). Their fur is grey-brown, dark brown, or reddish-brown on the upperparts, and is grayish-white on their underside. The water vole's large incisors, combined with its very large skull and well developed zygomatic arch (which strong chewing muscles attach to), contribute to its ability to efficiently dig tunnels and chew through tough roots. Behavior and ecology Habitat and feeding Water voles live in two distinct bands through the western United States and Canada, extending from British Columbia and Alberta through parts of Oregon, Washington, Montana, Idaho, Wyoming, and Utah. They are found in alpine or semi-alpine meadows near water, usually between 914-3,201 m in elevation. The distribution of habitats is found to be extremely variable, due to the geographical barriers of large coniferous forests, mountains, and expansive valleys without readily available waterways. Although, genetic data has been collected that suggests water voles do have the ability to disperse over land to reproduce with other populations, this overland dispersal between colonies tends to be higher with adjacent populations, and less so with increased distance. Because water voles live in such small isolated patches it is necessary for them to form such a metapopulation structure, in which dispersal can balance out local extinction. Their main source of food is vegetation, including leaves, stems, grasses, sedges, willows, and sometimes seeds or insects. Their food source varies significantly depending on geographic location. Studies have shown that water voles have a very high metabolic rate, and therefore don't have to consume as much food as other rodents their size. Most often, water voles feed on the subterranean portion of plants, which are available to them year round. There is no evidence that they store food for the winter. During the winter they are seen to dig tunnels through the snow, and usually do not surface above the snow once 6 cm have accumulated (approx. 7 to 8 months of the year). Water voles are most active at night, and they travel between tunnels, nests and waterways by means of surface runways 5–7 cm wide through the vegetation. Often tunnel or burrow entrances are found either at water level or submerged along the river