Water voles are small UK mammals, about the size of small guinea pigs but with furry tails.
They like to live on the banks of streams, rivers and ponds. We call this habitat 'riparian'. Water voles like banks thickly covered in grass and reeds that they can eat and where they can hide from the animals that eat them (predators). They also like the bottom of the river to be covered in mud, so that when they're escaping in the water, they can kick up a screen of silt and hide inside it.
Mostly they live inside the banks, in burrows that they dig with their strong teeth. These burrows are about as wide as a tube of Pringles, and round the entrance you'll see the grass has been nibbled short. These nibbled patches are sometimes called 'vole lawns'. Each vole will make lots of burrows so there's always a means of escape close by.
Water voles are pretty much entirely vegetarian. They spend a lot of time eating, and don't much mind what plants. I've even seen them eat nettles! They grasp each stem with their paws and bite into the middle, leaving a diagonal cut at the end. One of the most obvious signs that there are voles about is the piles of chopped-up vegetation they leave lying on the banks. The name for these is 'feeding stations'.
Voles are "at the bottom of the food chain", meaning a lot of other animals like to hunt them. Cats, dogs, owls, hawks, magpies, grass snakes, pike, polecats, weasels, stoats, heron, rats, otters and mink will all take water voles. Average life expectancy for a water vole is short; none of them get much past eighteen months. So to make up for this, they breed fast, females having anything up to five litters a year with 5-6 pups in each litter. They are also excellent at a fast getaway, either plopping into the water and swimming off or shooting down a burrow out of danger.
Because they're shy, it can be hard to tell whether water voles are present on a site. But they're helpful animals and leave us little signs. As well as the burrows and feeding stations, you can look out for 'latrines', piles of droppings that water voles use as signposts for other voles - "Keep out, this is my territory". Water vole poo is made up of brown-green pellets about the size of TicTacs, and it's often place somewhere prominent like a stone.
The sad news is that water voles are very endangered. A lot of their habitat has been destroyed by building or water pollution and their situation is getting desperate. So how can we help? Mainly by looking out for them, and by reporting any sightings of water voles or even just of their feeding, burrows or latrines. You can contact the Wildlife Trust if you suspect you have water voles living near you, and send in any photos you have of signs. Try and make sure no one mistakes them for rats and tries to poison them. And if you own a cat, keep it in at night, and attach a little cheap flashing light to its collar (this makes the cat safer on the roads anyway).