Ermine are adapted to a wide variety of habitats. It prefers wooded areas with thick understory near watercourses, and often occupies early-successional or forest-edge habitats, wet meadows, marshes, ditches, riparian woodlands, or river banks with high densities of small mammals and adequate subnivean foraging space. Coastal ermine may exhibit a preference for low elevation riparian and marine shoreline and estuarine habitats. They are well-adapted to snowy environments and range into alpine areas. They have been documented year-round living at 2,000–3,000 ft in the Sierra Nevada, California and also successfully inhabit tundra habitats throughout northern Canada and Alaska.