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Friday 6th September 2013

water vole feeding cpt Tom Marshallwater vole feeding cpt Tom Marshall

Records reveal water vole presence down 22%

Signs suggest the water vole is still struggling as new maps indicate the mammal’s presence may be down by more than a fifth, the Environment Agency and The Wildlife Trusts reveal.

The benefits of targeted and sustained projects are clear

New maps published today suggest that while there are some strongholds where water voles continue to thrive, the species remains vulnerable to further decline and extinctions, especially in parts of England, including the south west, south east, parts of the north west and some areas in the midlands.

Populations continue to disappear due to long-term habitat loss, mink predation and extreme weather events, including last year’s spring drought.

Creating and maintaining large-scale good quality habitat is key to ensuring the species’ survival.  Reintroduction schemes, combined with mink control programmes and habitat management are providing a lifeline for this much-loved species.

Paul Wilkinson, The Wildlife Trusts’ Head of Living Landscape, said:

“This latest information from the National UK Water Vole Database and Mapping Project is a real cause for concern. Not enough is being done to secure this charismatic species’ future.  In part, the new data reflects a reduced survey effort over the last few years, linked to a reduction in available funding for water vole conservation work.  There is clear evidence from some areas, in the south of England for example, that water voles are disappearing fast.

“Strongholds do remain, and these are often located in areas which support more extensive wetland habitats, such as the fens, or headstreams in upland areas.  We must ensure these strongholds persist and renew efforts to save this much-loved species, through targeted conservation action and sustained monitoring programmes.

Alastair Driver, Environment Agency’s National Conservation Manager and Chair of the UK Water Vole Steering Group, said:

“Creating new habitat helps protect our native species, like water voles and otters, and helps tackle climate change.  The Environment Agency has created nearly 5,000 hectares of wetland and river habitats in the last 10 years and we hope to double this in the next 10.  Added to this, our rivers are at their healthiest for over 20 years, but control of the American mink is essential if water voles are to benefit from these healthier rivers and new habitats."

The Wildlife Trusts and others are working hard to save the water vole, with projects that establish where populations remain and what needs to be done to help them re-connect and expand across larger areas.  Surveyors look for the occurrence of characteristic field signs such as droppings, feeding stations and burrows in order to detect their presence along water courses.

Paul Wilkinson continues:

“The benefits of targeted and sustained projects are clear. We have many examples of where recovery has been recorded and the water vole has extended its range due to the efforts of conservation professionals and enthusiastic trained volunteers.  We must ensure that this kind of targeted work is extended. Otherwise there is a risk that we will lose water voles altogether from large areas of the country."

The UK Water Vole Steering Group, which comprises representatives from the Environment Agency, The Wildlife Trusts, People’s Trust for Endangered Species, Natural England, Scottish Natural Heritage, Natural Resources Wales and the Scottish Environment Protection Agency, believes that a national water vole monitoring programme is needed.  Annually recording populations at a sample of key areas across the UK would provide a better indication of how this vulnerable mammal is faring over time.
 

Notes to editors:

The National Water Vole Database and Mapping Project, established in 2008 to collate and map water vole data from across the UK, recorded water voles in 874 10km squares in 2004-2008.  The latest mapping, for the period 2007-2011, shows water voles are now present in 683 10km squares - a decline of 22%.

Strongholds are identified in upland areas such as the Cairngorms, Snowdonia, the North Pennines, and the Peak District.  They are also in areas where there are extensive well connected wetland habitats such as the Humberhead Levels, the fens of eastern England, the Somerset Levels, the coastal grazing marshes of Lincolnshire and the extensive ditch systems of parts of Lancashire.  Rivers where habitat quality is good and where mink are absent continue to support robust populations, for example in parts of Buckinghamshire and Berkshire.

The latest data reveals that strong populations of water vole remain in parts of the UK which support several well connected populations, due to a combination of large areas of good quality habitat and absence, or low numbers of American mink

The water vole has suffered a long-term decline due to the deterioration and loss of wetland habitats as a result of development and agricultural intensification. Decline accelerated in the 1980s and 1990s due to a combination of habitat loss, population fragmentation and predation by American mink.  American mink are effective predators of water voles and can quickly eradicate colonies across large areas.

The impacts of drought and flooding have also added to the problems.  The early summer drought in 2011 is known to have led to dramatic reductions in water voles in some areas, as watercourses dry up and they become vulnerable to other predators such as stoats and weasels.  Populations at Greene King Water Meadows, Bury St Edmonds in Suffolk, for example, suffered heavily.  Flooding events can lead to water voles drowning in their burrow systems as river levels rise fast.

In areas where water voles are thriving, with several strong colonies living close together across extensive high quality wetland habitats, the species has a chance to survive the arrival of mink, drought and flooding.  However, many of remaining water vole populations are small and isolated, making them increasingly vulnerable to these devastating events.

Measures to conserve the water vole help to achieve many other biodiversity targets for wetland habitat and species conservation.  Water voles respond quickly to habitat change and are therefore an excellent biodiversity indicator species.  Previously an extremely common and widespread wetland mammal in the UK, an estimated 88% of the population was lost in seven years between 1989 and 1998 (Strachan, Strachan and Jefferies, 1998).

As a species which is known only to disperse around 500m-3km, the fragmentation of water vole populations increases the risk that local extinctions will be compounded into overall extinction.  Once isolated, a population of water voles becomes genetically ‘marooned’.  As populations of species become smaller, they become more vulnerable to chance extinction events such as disease, drought or the arrival of American mink, from which they find it increasingly hard to recover.  Populations in these situations can only be sustained by immigration of new genetic material (animals in this case) from an outside source (Strachan & Holmes-Ling, 2003).  Water voles naturally lose up to 80% of their populations over winter and rely heavily on their ability to sustain a core population over winter to breed profusely the following year.  There has been no national survey of the water vole since 1998.

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Tagged with: Species