Take a gander at brown rats and water voles...

That's a bit of mouthful - why have we chosen both rats and voles?
Surprisingly enough, these two are so alike, that even experts - and this includes pest controllers - mistake them for each other.

Brown rats are our most common mammal, but the water vole is in decline and the Wildlife Trusts are working hard to help the species recover.

So, if the experts have problems, how can I tell the difference?
Well, there are a few telltale signs you can look for. The water vole has small hidden ears, silky mid-brown fur, a blunter nose and a shorter furry tale. The brown rat has big ears, greyish-brown fur, a pointed nose and a long, pink, scaly, hairless tale.

A water vole nibbles an apple

Are they native to Britain?
Water voles are the largest British vole. At 12-20cm in length, they can weigh up to 320g. They have dark fur, a round body and a short, fat face. They have a long, fur-covered tail - and they're so cute!

Brown rats have been bred for research and the pet trade. They spread across Britain via the shipping traffic from foreign countries in the 18th Century, largely replacing the black rat. Along with house mice, they are considered to be the most widespread terrestrial mammal. Brown rats have coarse brown (occasionally black) fur, with a pale underside. They have a long tail, which is sparsely haired. At around 18cm in length, they can weigh up to 400g.

Where should I look for voles and rats?
Water voles inhabit the banks of ditches, dykes, slow-moving rivers and streams, as well as grassland.

Brown rats are highly adaptable and can be found in a variety of habitats, typically near human habituation.

A hungry brown rat. Photo courtesy of BBC Wildfacts

What do they like to eat?
Water Voles feed mainly on grasses and other plant material.

Brown rats are omnivorous but prefer starch and protein-rich foods, such as cereals. Their diet includes meat, fish, vegetables, weeds, earthworms, crustaceans, nuts and fruit. They sometimes cache food to return to later.

What are their habits?
Water voles are expert swimmers, but are not particularly specialised for a life in the water, unlike beavers and otters. They burrow into riverbanks and make a nest, which they line with grass. They are active both day and night.

Brown rats are typically nocturnal, although they will sometimes forage for food during the day. They live in loose colonies, made up of aggregations of clans - usually consisting of a mated pair, or a male and a harem of females. Clans will defend their territory from other rats, and there is a dominance hierarchy whereby the biggest rats are dominant over their smaller counterparts.

Cambridgeshire Mammal Atlas - help us to track the mammals in our county >>

You can find out more about Britain's mammals at BBC Wildfacts or BBC Life of Mammals or The Mammal Society.

The Mammal Society's Winter Monitoring Project is also looking for volunteers. It wants to know more about the future of different species. People who take part will be asked visit areas near to their homes to monitor mammal activity and look for any signs of mammals, like footprints or droppings. The Society - the only group dedicated to the study and conservation of all British mammals - says the initiative will help it learn more about different species in the UK, and provide important information about the state of the British countryside.

Get more information from The Mammal Society website or by ringing 020 7498 4358.

December is.... deer month >>

November is.... hedgehog month >>