The former widespread distribution and abundance of the water vole (Arvicola terrestris) has meant that it has attracted little or no previous conservation interest. However, its accelerating decline in numbers and the resulting fragmentation of its population is of great concern.

As one of the main characters in the Children’s classic The Wind in the Willows, the water rat, or water vole as it is properly called, is a well-liked and familiar animal amongst the general public – with their short, blunt muzzle, small hairy ears and plump, rounded body. Water voles are not overly sensitive to the presence of people and may be easily seen during the day in areas where they still survive. This high profile presents opportunities to bring the species’ plight to the attention of London’s public, publicise the progress of the Action Plan and involve people in its conservation.

The water vole is potentially an excellent flagship species, whose presence reflects healthy waterside habitats and their associated plant communities.

The changing fortunes of the British water vole population through the 20^th century has only recently come to light, following the pioneering national surveys conducted by the Vincent Wildlife Trust in 1989-90 and 1996-98. These surveys confirmed that the species has become progressively scarcer along our waterways since the 1930s, as the result of habitat loss and land-use changes associated with the intensification of agriculture in the wider countryside. Since the 1980s, this decline has accelerated due to predation by feral American Mink (established as escapes from fur farms). The decline has now developed into a serious population crash with a further 88% loss to the remaining populations in only seven years (1991-1998). This makes the water vole the most rapidly declining mammal in Britain.

In Greater London the water vole has disappeared from over 72% of the sites it occupied before 1997 (LMG Greater London Water Vole Survey 1997). Although the species still retains a widespread distribution around much of London’s periphery (especially in the Boroughs of Barking and Dagenham, Barnet, Bexley, Ealing, Enfield, Greenwich, Hackney, Havering, Hillingdon, Hounslow, Redbridge, Richmond, Waltham Forest), populations are highly localised and fragmented.

The many factors that influence the survival of this species are outlined below. They are listed in order of priority, but each may have a greater or lesser local effect depending on the robustness of the individual populations and their habitat.

This is viewed as being a major factor of concern. Loss of wetland habitats has reduced populations and left them more vulnerable to other threats such as predation. Development, land drainage, low water levels, river engineering and changes in waterside management have all destroyed habitat. Intensive grazing and trampling by livestock along watercourses also contributes greatly to habitat loss in some of the more rural boroughs.

The arrival and spread of mink along a waterway has been found to have serious consequences for water voles and rapid extinction of some water vole colonies has been recorded. Mink predation is influenced and exacerbated by other threats such as habitat loss. The current status of mink in the London boroughs is unknown.

Water voles are relatively tolerant of human recreational activities (dog walking, angling and boating) along waterways as long as they have vegetation cover in which to hide.

Water voles appear to be relatively tolerant of low water quality but the full impacts of different types of pollution such as industrial effluent are unknown. Low flows and droughts such as those caused by over-abstraction of groundwater can lead to localised loss of water voles. By contrast, prolonged flooding can also be detrimental.

Poisoned grain or similar rodenticides placed for rats or mice may be taken by water voles if placed along a watercourse. The proliferation of rats along a waterway, attracted by litter and human refuse, may be detrimental to water voles which may be out-competed or even fall prey to their larger cousins. Carried out carefully, rat control has been shown to be beneficial to water voles.

The water vole has been given legal protection under the Wild Mammals (protection) Act 1996 and Schedule 5 of the Wildlife & Countryside Act 1981 (as amended).

The Wildlife and Countryside Act protection makes it an offence intentionally to;

Practical advice about water vole conservation and habitat management has been summarised in The Water Vole Conservation Handbook (Strachan 1998). Educational resources include the Focus on Water Voles slide pack produced by The Wildlife Trusts.

Flood defence management of waterways is being carried out in accordance with best practice guidelines to maintain water vole populations.

Local Environment Agency Plans (LEAPS) and Water Level Management Plans now consider the requirements of water voles and implement actions when appropriate.

Many Local Authorities and organisations are already promoting water vole conservation through habitat enhancement projects, surveys and publicity campaigns.

National Research is currently underway investigating translocation and reintroduction as methods to aid the species recovery.