How to tell the difference between an otter and a mink

American mink have spread rapidly across Britain since they first escaped from fur farms 50 years ago. Now firmly established along rivers and lakes, these newcomers can easily be mistaken for otters, since both are long and slender with short legs and long tails. So how do you tell them apart?

Eurasian otter © Ed Evans / Getty

FACTFILE: EURASIAN OTTER 

Scientific name: Lutra lutra

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Nose: Rounded

Markings: Throat and chin brownish white

Colour: Usually pale brown

Tail: Thick and tapering with short hairs

Size: Adults distinctly bigger than a cat

What can I look for in water? A swimming otter is mostly submerged and creates a broad, U-shaped wave on the surface with its nose.

What can I look for on land? Otters leave prominently placed spraints on regular territory-marking spots, such as waterside logs and rocks. Spraints are messy smudges with a distinct, not unpleasant smell and contain bones and fish scale remains. Tracks are usually at least 2cm wide (wider than your thumbprint).

Habitat: They can be found beside rivers, streams and lakes, mostly in north and west England and Wales. Also found along the west coast of Scotland. Shy and mainly nocturnal though coastal otters can be seen during the day.

American mink © Paul Reeves / Getty
American mink © Paul Reeves / Getty

FACTFILE: MINK 

Scientific name: Mustela vison

Nose: Pointed

Markings: Sometimes has a pure white spot under the chin

Colour: Usually very dark, almost black

Tail: Almost bushy when dry

What can I look for in water? A mink swims higher out of the water than an otter, so the whole length of its back is often visible. It creates a narrow, V-shape wave on the surface with its nose.

What can I look for on land? Mink deposit scats in similar locations to otters. They are 3cm long, black, smell distinctly nasty and contain fur, feathers and bones. Their tracks are barely 1cm wide (narrower than your thumbprint).

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Habitat: Found beside rivers, streams and lakes over most of lowland England and Wales. Also can be found along areas of the Scottish coast. Mink are bolder than otter and can be seen day and night.