Water voles hold the unfortunate title of being the UK’s fastest declining mammal. Once a common and widespread species in Britain, a recent report has revealed an estimated 30% decline in water vole distribution across England and Wales between 2006 – 2015. However, there is some evidence that conservation work, including strategic habitat restoration and reintroductions, is starting to reverse this trend on a local scale.
In this guest blog post Lowri Watkins, Gwent Wildlife Trust’s Water Vole Project Officer, working on the HLF-funded Magnificent Marshy Mammals Project, talks us through the highlights and challenges of monitoring our waterways for this charismatic creature.
National Water Vole Monitoring Programme
The National Water Vole Monitoring Programme (NWVMP) was launched by People’s Trust for Endangered Species (PTES) in 2015 with the aim of establishing where water voles remain and how many there are, building knowledge which can inform conservation efforts for the species. Gwent Wildlife Trust (GWT), like many others, submit the results of our surveys to this important scheme, in the hope of increasing understanding.
In 2012, GWT reintroduced over 200 water voles to our Magor Marsh Nature Reserve on the Gwent Levels, returning them to a landscape in which they would have once flourished. We’ve been monitoring our population ever since, surveying ten transects twice a year (May and September). These surveys help us to assess relative population numbers – how the population has fared over winter and how successful the breeding season has been. As well as taking stock of numbers, the survey results also reveal distributions and densities across the site, which helps to inform our management priorities.
Preparing to survey
By the end of winter, the water vole population will have plummeted to its lowest number, as harsh weather, reduced food stocks and hungry predators all take their toll. Water voles, like most rodents, are a short-lived species, with most individuals only making it through their first winter and rarely a second. So I always look to our post-winter survey with bated breath!
Water voles range from being surprisingly bold to incredibly elusive, but fortunately, they leave behind a variety of clues to signpost their presence – burrows, footprints, pathways, feeding remains and one of the most conclusive signs – piles of droppings which we refer to as ‘latrines’. It is these signs which we look for when conducting a survey, with live sightings being a rare but pleasant bonus!
We plan our survey for early May, giving the water voles a head start, but not late enough that thick vegetation gets in our way. We use the survey as an opportunity to train new volunteers, allowing them to gain hands-on experience and contribute to an important monitoring project. In the days leading up to the survey, we cross our fingers for dry weather; heavy rain can wash away the majority of signs, as well as raise the water levels and make the banks unstable.
Searching for signs
Our beautiful Magor Marsh Nature Reserve is criss-crossed by several kilometres of ditches and reens, providing an ideal habitat for water voles. These waterways are lined with dense and varied vegetation, the perfect banquet for a herbivore that needs to eat up to 80% of its bodyweight every day!
Starting our day off with a short presentation on water vole ecology and signs at our education centre on site, we then split in to five groups and head off to survey the first of our five ditches, with long sticks to hand. In small groups we move along the transect, leap-frogging each other as we search every metre or so along the bank. We’re careful not to trample the ground, especially closer to the bank where it can be softer and burrow entrances more concentrated; this is where the stick comes in useful, giving us extra reach to search with minimal disturbance.
For the last couple of years, I’ve led the hunt for signs on what we fondly refer to as ‘water vole alley’. It’s a picturesque ditch which travels past wet woodland, thick reeds and a popular section of footpath. It has earnt this name due to consistently turning up the highest count of latrines of all our transects, but it also has some of the trickiest terrain – tall reeds, dense nettles and bramble patches. It’s challenging, but very rewarding!
We won’t have gone more than half a metre before we find our first signs on water vole alley. Excitement builds among the trainees, as we all gather round to marvel at a small pile of droppings, barely discernible from the mud below it. We continue on with renewed energy; the trainees are keen to spot signs for themselves and we usually end up crowning one lucky individual our ‘Chief Dropping Spotter’.
A few metres on and the cries come in, one after the other – “I think I have a feeding station!”, “Me too! ..and a latrine”. I dip in to confirm them as being water vole and eagerly note them down on my survey form. By the end of our 200m search, our tally stands at an impressive 25 latrines, 15 burrows and 34 feeding remains, along with evidence of pathways, footprints and even a live bank vole sighting.
We return to the centre for a much needed lunch break and after topping up our sun cream, head back out to survey the final five ditches. The second of my ditches runs between two wet meadows, it’s deeper, with near vertical banks – perfect for burrowing into, but the vegetation is noticeably less varied and dense. The signs here are far less numerous, we find only a few latrines and feeding stations, but the trainees are thrilled to spot and sniff an otter dropping on the sluice, another sign which we record.
After completing all the ditches, we reassemble back at the centre for a debrief on how the day has gone. The preliminary results are looking good – we’ve detected water vole signs on each of the ditches surveyed and one of the groups even saw a live water vole! Everyone has seen examples of each of the signs and feels confident about identifying these without assistance. Most pleasingly, water vole alley has proudly retained its record of being the most active ditch!
In the days after the survey, I’ll digitise the survey forms and input the data into our GIS database, allowing us to see how the signs look spatially. Next I’ll log onto to the PTES website and upload the results there too. Come September we’ll repeat our survey, when I hope to find even more signs and evidence of a successful breeding season and maybe even a live water vole or two!
How to get involved
You can register for the National Water Vole Monitoring Programme on here and search the map for a site near you that needs monitoring.
If you’re new to water vole surveying, get in touch with your local Wildlife Trust, mammal or wildlife group to find out about local monitoring you could get involved in or whether it would be possible to join an experienced monitor while they are conducting a survey. You can also look for practical training courses, to learn about water vole ecology and survey techniques from experienced surveyors. Many Wildlife Trusts run practical courses, often free to conservation volunteers.