Stoat or weasel? How to tell the difference

Stoats and weasels are both small, brown, fast and ferocious mustelids with sinuous bodies and short legs. So how do you tell the difference?

Stoat (Mustela erminea)

Stoats and weasels aren’t unusual in the British countryside, but you don’t get to see them very often. And when you do, it’s often not much more than a quick flash as they streak through the grass in front of you. The differences between stoats and weasels aren’t huge, but when you know what to look out for, it’s not too hard to know whether you’re watching a stoat or a weasel.

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FACTFILE: STOAT

Scientific name Mustela erminea

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

Stoat (Mustela erminea) showing off its characteristic black-tipped tail
A stoat showing off its characteristic black-tipped tail. © Nature Picture Library/Getty

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

Ermine stoat (Mustela erminea) in winter coat
A stoat in its white winter coat. © Fabrizio Moglia/Getty

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

Adult weasel leading its young across a path
Adult weasel leading its young across a path. © Andre Simon/Getty

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

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

Weasel with a mouse it's just killed
Weasel with its mouse prey, giving a good idea of just how small weasels are. © Andyworks/Getty

Stoat vs weasel

  • If it’s got any white on its back, it’s a stoat, as weasels don’t turn white in winter in the UK
  • Stoats have a longer tail with a black tip all year round – this is the key distinguishing feature
  • Stoats are bigger than weasels, but that can often be hard to tell in the field
  • Stoats are bouncier than weasels when they’re running; a running weasel tends to be quicker and lower to the ground
A stoat hunting on a rocky outcrop
A hunting stoat. © Stein Nilsen/Getty
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And of course, based on all the known evidence, if you see a small predator riding a woodpecker, it’s probably going to be a weasel…