Water Voles

Water VoleWater Vole. Credit: Terry Wier

The water vole is found throughout Britain, though it is less common on the higher ground. It is frequently recorded from parts of northern Scotland and is absent Ireland. It is usually found near open water and dives and swims with great ease. Water voles are sometimes confused with brown rats, which often also live near water. Indeed it is sometimes called ‘the water rat’, which is the origin of the water voles fame as ‘ratty’ from Kenneth Graham's book ‘The Wind in the Willows’.

Water voles occur mainly along well-vegetated banks of slow flowing rivers, ditches, dykes and lakes. They eat grass and waterside vegetation; 227 plant species have been identified in their diet, though other broad-leaved plants may also be eaten at certain times. Water voles excavate extensive burrow systems into the banks of waterways. These have sleeping/nest chambers at various levels in the steepest parts of the bank and usually have underwater entrances to give the animals a secure route for escape if danger threatens. ‘Lawns’ of closely cropped grass, occasionally with piles of chopped food, may surround burrow entrances. Water voles tend to be active more during the day than at night. Male voles live along about 130 metres of water bank, while females have a range of 70 metres long. They deposit distinctive black, shiny faeces in latrines. Laterines occur throughout and at the edges of their range during the breeding season.

Water voles usually have 3 or 4 litters a year, depending on the weather. In mild springs the first of these can be born in March or April, though cold conditions can delay breeding until May or even June. There are about 5 young in the litter, which are born below ground in nest made from suitable vegetation, notably grasses and rushes. Although blind and hairless at birth, young water voles grow quickly, and are weaned at 14 days. On average water voles only live about 5 months in the wild. Their most important predator is minks and stoats, though herons, barn owls, brown rats and pike are also known to take them.

Recognition:

Water voles are rat-sized with blunt nose; chestnut-brown fur; short rounded ears; long hair-covered tail.

Head/body length: 140-220cm; Tail: 95-140mm;

Weight: 150-300g

Conservation:

Water Voles are protected in the UK under the Wildlife and Countryside Act, 1981, and classified as a Priority Species in the UK Biodiversity Action Plan.

On the continent they behave quite differently, living away from open water and are regarded as serious agricultural pests. In Britain, water voles occasionally undermine riverbanks, but otherwise they are harmless and cause no damage.

Recent evidence suggests that water voles have undergone a long-term decline in Britain. On current trends it is predicted there may eventually disappear from 94% of their former sites, a decline exceeding even that for the otter.

Predation by the introduced American mink is thought to have a severe impact on the water voles populations, even causing local extinction. This may be because their usual way of evading predators, by diving and using burrows with underwater entrances, does not protect water voles from the mink. Removal of mink is unrealistic for larger areas but can be carried out local in nature reserves and along key sections of rivers to protect remaining water vole population.

Habitat degradation and pollution are also thought to have contributed to decline of the water vole. Riverside works such as dredging and clearance of bank side vegetation removes large amounts of the plants water voles depend on for food and cause disturbance. A more sensitive approach to riverbank management needs to be encouraged to protect water voles. Dredging and other work should be scheduled so it does not affect both banks simultaneously and retention or planting of bank side vegetation carried out wherever possible.

Water voles are also probably affected by poor water quality, both directly through contamination of water bodies with pollutants and indirectly through eutrophication the build up of nitrogen levels in water which caused algae to bloom and loss of water vole food plants.

Water Vole FAQs:

How do I distinguish water voles from brown rats?

The ears of the water vole are hardly visible, unlike those of the rat, which stands out. The tail is furry whilst that of a rat is naked. The muzzle of water vole is blunt, not pointed, its fur is redder and tail is shorter. When disturbed they dive with marked ‘plop’.

What are the main field signs of a water vole?

They leave characteristics tracks in mud flats close to the water. The forefoot has 4 toes which leave a distinctive star shaped pattern, while the hind has 5 toes with the first and fifth toes leaving prints almost at right angles to the 3 central toes.

How do water voles patrol their range?

By a combination of swimming and running short distances at the water's edge. They enter and leave the water at a number of fixed points.

Do they eat fish?

They will eat dead fish, but never catch them.

Are there black water voles?

Yes, in northern Scotland and locally in East Anglia.