Citizens' science to save our water voles - volunteers needed!

Water vole in Arundel, England. Photo: Peter Trimming via Flickr (CC BY).
Water vole in Arundel, England. Photo: Peter Trimming via Flickr (CC BY).
UK water voles face an uncertain future after widespread habitat loss and predation by American mink, write Emily Thomas and Nida Al-Fulaij. But you can help by joining a UK-wide monitoring scheme run by the People’s Trust for Endangered Species that's recruiting nature-loving volunteers to survey local lakes, rivers, ditches and streams for signs of these lovable but elusive creatures.
Conservation groups are working hard to try and save the much-loved water vole. However, it's difficult to track the effectiveness of their work without seeing how the national picture has changed - and that's where the Monitoring Programme comes in.

Water voles were once a familiar sight along our waterways. But over the last century they have experienced the most serious decline of any British wild mammal.

This shocking drop in numbers is due in part to habitat loss and destruction along many of our waterways over the last century as riparian vegetation along streams and rivers has been cut back and grazed down.

On top of that our water voles have suffered from the attentions of American mink, a voracious predator that has been escaping from fur farms or deliberately released into our countryside since the 1920s.

Two national surveys were conducted by The Vincent Wildlife Trust during the 1990s which demonstrated the dramatic decline in water voles across Britain: water vole numbers had plummeted by almost 90% in that decade alone. Water voles have been immortalised as the lovable Ratty in Wind in the Willows and they are a key part of our natural heritage.

They play an important ecological role along waterways - as an indicator of a healthy environment, and providing food for a range of native predators. They have even been found to affect the bankside plant diversity through the creation of their burrow networks.

Tails from the river bank

While they can be confused with rats, they are distinctly different. They are the largest of the British voles, about the size of a guinea pig, with a round, chubby body, blunt nose and small ears hidden in thick fur. Whilst they are usually dark brown, black water voles can also be found, especially in Scotland.

And if all you get to see is the tail as Ratty (of either species) dives into the water, that's enough for an identification. Rats have hairless tails as long as their bodies. Water vole tails are covered in hair and about half their body length.

Over the last couple of decades conservation groups have been working hard to try and save the much-loved water vole. However, it's difficult to track the overall effectiveness of this work without seeing how the national picture has changed since the 1990s, and that's where the National Water Vole Monitoring Programme comes in.

People's Trust for Endangered Species (PTES) launched the first National Water Vole Monitoring Programme (NWVMP) across England, Scotland and Wales last year, working in collaboration with The Wildlife Trusts, Natural Resources Wales, Scottish Natural Heritage, The Environment Agency, Natural England and the RSBP.

The NWVMP aims to ensure we have a better picture of what is happening to the species nationally and that we are in a position to act quickly when needed, by bringing together all current monitoring efforts, as well as resurveying sites from the previous national surveys to see how things have changed.

Conservation groups are working hard to try and save the much-loved water vole. However, it's difficult to track the effectiveness of their work without seeing how the national picture has changed - and that's where the Monitoring Programme comes in.

However, for the programme to collect robust data, we need an army of volunteers surveying sites across the country so we can see what is happening at a national, country and regional level. Last year 188 sites were surveyed and had data submitted online which was a fantastic start to the programme.

While the initial data looks encouraging we would like to increase the number of sites being surveyed, so we can start to build up a large dataset that can be used to establish reliable trends.

Join in our national water vole survey!

We are asking volunteers to get involved with the NWVMP by registering online and then selecting a site to monitor annually, either choosing one of the preselected sites or registering their own site. Volunteers will then need to survey one 500m length of bank at their site once during May, recording all signs of water voles, otters and mink.

As with many mammals, it's not always possible to see water voles - even if they are present. So the best way of confirming their presence is to keep an eye out for signs they have left behind. These include their droppings (usually left in piles called 'latrines'), feeding signs / remains, burrows in the bankside, or in certain habitats, nests.

Latrines, feeding signs and actual sightings of the animals are all accurate ways of telling us that water voles are living in the area. Burrows can persist for a number of years however, so cannot be used as evidence of current occupation.

Latrines are the most distinctive and reliable sign that water voles are in residence. Droppings are cylindrical with blunt ends, usually 12mm long and 4-5mm wide, resembling a large ‘tic tac'. The colour varies depending on the diet, ranging from green through to dark purple/black.

Feeding remains are often neat piles of chewed lengths of vegetation that are left after feeding - water voles need to consume 80% of their body weight every day and spend most of their time eating, so if they are in the area you are likely to see these signs.

Sections are typically 8cm long and have 45 degree cuts to their ends. Water voles have been found to eat 227 different species of plants but the most commonly eaten are coarse grasses, reeds, sedges and rushes. Breeding females have even been known to feed on frogs to give them extra energy, but they're usually vegetarian.

Small holes in the river bank

Water vole burrows appear as a series of holes along the water's edge, some just above or at the water level on steep banks, others can be below the water level, ensuring the water vole has a number of escape routes available.

There can also be burrows occurring further up the bank, up to 3m from the water's edge. The holes are typically wider than they are high with a diameter of 4-8cm.

But there's another sense to bring into play here too - your hearing. All too often if you come across a water vole, it will see you long before you ever see it. Get too close, and it will drop into the water with a characteristic 'plop' - and if you're lucky, you might just retain a brief retinal imprint of a swift brown flash.

That may not be enough for a positive identification, but it's a clear indication that you're in water vole country. So sharpen up - and keep your eyes open for more definite signs.



Volunteer to monitor a site or register a site you are already watching with the NVWMP - before the beginning of May.

Emily Thomas is Key Species Monitoring Officer for PTES, and coordinates the National Water Vole Monitoring Programme.

Nida Al-Fulaij is the Grants Manager at PTES who oversees the distribution of grants to a variety of conservation projects both nationally and internationally.


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