How to tell the difference between a stoat and a weasel

These little brown mustelids are both fast and ferocious, with sinuous bodies and short legs. So how do you tell them apart?

Stoat © Mike Lane / Gett

FACTFILE: STOAT

Scientific name Mustela erminea

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Body Long and lithe; roughly the size of a thin rat

Size Up to 25cm long (head and body); male is noticeably larger than female

Flanks Uniformly brown; form a straight, contrasting line with pale belly

Throat No brown patches

Tail Medium length; rearmost third always black

Underside Creamy white

Where do I look? Near rabbit warrens, where it often hunts in daylight, sometimes stalking prey in the open. Nests in old burrows

Does it go white in winter? Yes. White forms are common in northern Britain, but rare in the south. The tail tip stays black

Any other signs? Scats are long and slender, measuring up to 8cm long

Habitat Open country and drystone walls throughout Britain and Ireland

Food Mainly rabbits; numbers decline when rabbits are scarce

Weasel © Mike Lane / iStock (captive animal)
Weasel © Mike Lane / iStock (captive animal)

FACTFILE: WEASEL

Scientific name Mustela nivalis

Body Ultra-slim; about twice the size of a house mouse

Size Up to 20cm long (head and body); more slender than a stoat. Sexes are similar in size

Flanks Dividing line between tawny brown back and pale belly patchy and irregular

Throat Brown patch or ‘gular spot’ on each side

Tail Entirely brown; very short and often hard to see

Underside Pure white

Where do I look? Wooded areas with plenty of cover and along overgrown hedges and banks. Nests in empty mouse holes

Does it go white in winter? Not in Britain – remains a rich, tawny brown all year. In Europe, some do turn white

Any other signs? Scats similar in shape to stoat’s but smaller – up to 5cm long

Habitat Hedgerows, woods and rough grassy banks; absent from Ireland

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Food Mainly voles and mice, some of which may be caught in their burrows