A slender mustelid with a black tail tip. In summer its upperparts are brown and its underside is pale.
In cold areas such as the Scottish mountains, some turn white in winter while retaining a black tail tip.
In north-western Finnish Lapland, stoats did not all use the same habitat. Researchers radio-tracked eight females and seven males in 1998 and 1999. Mature females occupied areas where their preferred prey, voles of the genus Microtus, were most abundant. Dominant males used areas with fewer prey than females did, but more than other mature males.
Home-range size and habitat use also differed between the sexes. Both sexes were more active during the snowless, non-breeding season than during the breeding season. The findings link where these local stoats spent time with prey availability and social rank.
IUCN Red List · Least Concern (LC) · Global species-level assessment (Mustela erminea)
The global IUCN assessment lists the stoat as Least Concern (LC). It was assessed on 2 May 2015, published in 2016, and is marked as needing an update on the current IUCN page.
The 2021 regional assessment classified stoats as Least Concern (LC) across Great Britain but Near Threatened (NT) in Wales. The report says occupied grid squares fell 22% between the 1960–1992 and 2000–2016 atlas periods, while population trends could not be determined from the available data. The Mammal Society’s current species page instead lists Wales as Least Concern (LC), so the published sources conflict.