Dens often have a side chamber used as a store room for surplus slain mice. Weasels use forested, brushy, and open country. On the Arctic Slope and in the plateau areas they primarily live in areas of geographic relief such as slopes, rock slides, and stream banks. Weasels typically do not occur in wet sedge or grass meadows. However, they will move into the lowlands during the peak portion of lemming cycles.
Most weasel activity occurs at or near ground level.
However, weasels will occasionally climb trees. On the other hand, least weasels move less extensively. As with most predators, fluctuations in prey numbers create corresponding variations in weasel numbers. Weasel trails may appear quite erratic. However, weasels have definite movement patterns.