The water vole was once one of our most common British mammals and is famously known as 'Ratty' in Kenneth Grahame's classic children's tale, The Wind in the Willows.
Despite being sometimes referred to as a 'Water Rat', there is no such thing - there are brown rats, black rats and water voles. Water voles are a similar size to rats and brown in colour, but are distinguished by their blunt nose and rounded face, a furry tail and small ears. Some people say they look a bit like miniature beavers.
Water voles are a vital part of river ecosystems and are a keystone species. Their burrowing, feeding and movements help to create conditions for other animals and plants to thrive - a bit like beavers do, but on a much smaller scale. Their activity can help provide flower rich bank habitat for insects such as bumblebees, moths and butterflies who need nectar or pollen, or both, which become food for insect-eating birds and bats. Their burrows are also used by a range of other small mammal species, reptiles, amphibians and insects as shelter.
Sadly water vole numbers have plummeted from 1.2 million in 2002 to around 100,000 by 2018 and they are on the brink of extinction. In 2018 the National Water Vole Database and Mapping Project revealed that water vole distribution had plummeted by nearly a third across England and Wales. The study analysed data collected by The Wildlife Trusts over a ten year period and found a 30% drop in places where water voles were historically found.
Like many other places, water voles used to be seen and heard regularly along ditches, streams and rivers across our county but it has now been over ten years since a water vole was officially recorded in Surrey and we believe the species has sadly become locally extinct.
It’s believed the main reason for the dramatic decline of the species in Surrey and elsewhere is two-fold: the widespread destruction and degradation of wetland habitats and the populations of non-native American mink, which prey on water voles.
Habitat loss through the mismanagement and urbanisation of river channels and development of flood planes has lead to a loss of food, shelter and burrowing sites, whilst the pollution of waterways and industrialisation of agriculture has also impacted their populations through actions such as chemical runoff, livestock poaching (the trampling of the river bank) and overgrazing of riverside habitats.
The predation by American mink which were brought to the UK for fur farming, has had a major impact on water vole populations. Mink are good swimmers and females are small enough to enter the water-line burrows of water voles. Preying on the smaller mammals to feed their kits, they can wipe out an entire water vole population in one breading season.
Climate change is also not helping the plight of the water vole, with more extreme and regular flood and drought events impacting their riverside habitat.
So what can we do to bring back Ratty?
The cooperation of environmental charities, landowners, agencies and local authorities in restoring waterways, sympathetic management and smart planning decisions can go a long way in improving our rivers for water voles and other important wetland species. The control of the non-native invasive American mink is another important, if controversial tool in aiding the recovery of water voles, so great are their impact on their numbers.
Here at Surrey Wildlife Trust we continue our river restoration work through our RiverSearch project and work hand-in-hand with private landowners and other organisations to improve waterways for water voles and other important mammals such as otters.
This means literally, starting from the ground up by restoring the habitats for the invertebrate prey species on the river bed known as riverfly, which are then eaten by larger aquatic organisms and so on up the foodchain to apex predators.