How to tell the difference between a brown rat and a water vole

When all you’ve seen is a flash of brown fur, it can be hard to know whether it was ‘Ratty’ or the rat. Though the two species tend to live in different habitats, there are areas where they overlap, potentially leading to cases of mistaken identity. So how do you tell them apart? 

Brown rat (captive) © Mike Lane / Getty

FACTFILE: BROWN RAT 

Scientific name: Rattus norvegicus 

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Fur: Mainly pale grey-brown; grey-white on flanks and belly

Size: Males can be up to 50cm long (head and body 25cm, tail about the same).

Ears: Prominent and pale and stick up above head

Nose: Pointed

Body: Long and lean

Tail: Scaly, thick and very obviously long – more than half the body length

What can I look for on land? The rat’s prominent ears and long, scaly tail are key identification features.

What can I look for in water? There’s possible confusion here because rats can also swim well. However, unlike water voles,they won’t dive if alarmed.

Any other signs? Groups of oval droppings and burrows with obvious trails

Habitat: They can be found close to human habitation – around buildings, farmyards, rubbish tips and gardens, also urban waterways.

Water vole © Mike Lane / Getty
Water vole © Mike Lane / Getty

FACTFILE: WATER VOLE 

Scientific name: Arvicola terrestris

Fur: Dark chocolate brown, yellowish on flanks

Size: Males can be up to 20cm long (head and body); tail half the length of a rat’s.

Ears: Small and dark and buried in fur

Nose: Chubby and rounded

Body: Rounded and chunky

Tail: Furry, thin and hard to see and it’s short – less than half the body length

What can I look for on land? The blunt head, brown fur and short, hairy tail that’s hard to see. Their tracks are easy to identify – the forefeet have four toes, while the hindfeet have five.

What can I look for in water? Swims well and dives with a loud ‘plop’ if alarmed.

Any other signs? Substantial piles of droppings at the water’s edge. Voles also eat aquatic vegetation and leave bits lying around. Their burrows are similar to those of rats.

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Habitat: around in and around rivers, ditches, ponds and along urban waterways.