Hertfordshire Biological Records Centre - Projects

Water voles

The water vole is an indicator species. Their presence reflects both good water quality and healthy plant communities along the river bank. Their diet consists of reeds, sedges, coarse grasses and aquatic plants. Their river bank holes are often surrounded by patches of closely cropped vegetation and piles of chopped reeds known as lawns. The Water Vole is the largest of the vole family being rat sized but with a chubby face, blunt nose, chestnut fur, short round ears and a furred tail up to two thirds of the animal's length. Each population inhabits about 130 metres of water bank, marking their territory with latrine sites. Water Vole latrines consist of cylindrical droppings deposited along the water’s edge. Their distinctive droppings measure 8-12mm by 5mm. Water voles like to make their homes along densely vegetated river banks or ditches where the current is slow.

Do you know where there are water voles? The monitoring survey has highlighted the plight of the water vole and reflected the state of some of the rivers of Hertfordshire. Water voles may never be as common as they were earlier in the century but with prompt action the existing populations could be given the opportunity to stabilise and recover. Repeat surveys would help to monitor the health of aquatic habitats and should be undertaken at regular intervals.

The complete list of known water vole sites is held at HBRC. Records for the database are always welcome. Species information is a vital part of the planning process and helps to protect important wildlife sites.

If you have any water vole sightings send your records into the Hertfordshire Biological Records Centre stating -

What was recorded
Where - giving O.S. grid reference if possible.
When - date and time of sighting
Who - details of who made the record

The Hetrfordshire Mammal Group have contributed information to the water vole survey and are continuing to research into Hertfordshire’s mammals. New members are always welcome.

The water vole has declined for a number of reasons - the factors listed below do not act in isolation but in combination.

Disturbance of riparian habitats. Many water courses have been damaged by expansion of urban areas, intensification of agriculture and dredging works. Reprofiling of banks may leave them unsuitable for burrow formation
Fragmentation and Isolation of Habitats and Population. Water voles live in localised groups. The removal of bankside vegetation with increased predation results in isolated communities which are unable to colonise other areas leading to local extinction.
Predation by Mink.The introduced American mink is now widespread and occurs along many of the rivers in Hertfordshire. Mink were recorded from 5 sites where water voles were no longer present.
Deterioration of water quality and quantity.Climatic factors together with increased abstraction reduces water flow. Six of the survey sites were completely dry. Water quality has been consistently reduced by many pollutants. Over 50% of the sites visited in 1996 showed signs of eutrophication.

< Back :: Contact us