Small, chunky owl with a large, flat-topped head. Note extensive white spotting and gray face framed in black. Inhabits boreal, highland, and mixed woodlands; nests in tree cavities. Can be very difficult to find by day. At night, listen for fast tooting song, which can be confused with a displaying snipe; note clearer whistled tone and steadier volume. Populations move in response to winter conditions and prey populations, with large numbers moving south of typical wintering range some winters. Sometimes hunts small rodents around bird feeders. In Eurasia, compare with Eurasian Pygmy-Owl, which is smaller, has a less distinct facial disc, and finer spotting. In North America, distinguished from Northern Saw-whet Owl by its colder gray-brown coloration and spotted (not streaked) forehead.