Black water voles
How ‘Ratty’ has colonised a Scottish city
The last time I went looking for water voles with wildlife photographer Laurie Campbell, we were high on a moor in Scotland’s Monadhliath Mountains. The silence was so intense I could hear the sound of my pen as I scribbled notes. Crouching beside a ditch, Laurie pointed out the neat ‘lawns’ at the water’s edge where the grass had been nibbled short by water voles. I heard a sudden, soft ‘plop’, saw a twitch in the tussocky grass… but nothing more.
Today we’re on the edge of the M8 motorway, which slices through the centre of Glasgow, relentless traffic thundering by. We’re just below a retail park and along the steep earth slope, among discarded coffee-cup lids and sandwich wrappers, are small, round holes: water vole burrows. We’re here with zoologist Robyn Stewart, researcher for the Glasgow Water Vole Project, who is giving us a tour of her unlikely beat.
LOOKING OUT OF PLACE
It just so happens that the East End of Glasgow, including a few kilometres of motorway corridor, city parks and housing estates, hosts the highest density of water voles anywhere in the UK. You could hardly conceive of a less promising place to find a species that’s not only one of our fastest declining mammals, but also popularly associated with idyllic, languid backwaters.
We continue to a nearby park, and settle, binoculars poised, beside a gentle slope. Within a few minutes a black face appears at a burrow entrance. My first water vole sighting comes with a start of familiarity, nostalgia even – why, it’s Ratty! Then another one, chocolate-brown this time, scuttles out – quivering, dashing around like a small guinea pig in a hurry – and disappears again.
As I tune in, I see more and more burrows, and water voles popping up like jack-in-the-boxes. Right here, in an otherwise normal inner-city park, against a backdrop of grey tower blocks, with kids cycling, mothers pushing buggies and dog walkers strolling by. It feels incongruous, verging on surreal. For a start, there’s no water! Surely ‘Ratty’ should be messing about on a riverbank? Every field guide worth its salt tells us to look for water voles beside slow-moving rivers, canals, streams or marshy pools.
In the UK Arvicola amphibius is normally ‘riparian’ – living beside water – but across the species’ broad range from Spain to Siberia many of its populations are ‘fossorial’ – non-aquatic, living in grassland and burrowing like moles. Sometimes these fossorial water voles occur in large numbers and are considered a pest of farmland and gardens. So our ‘watery water voles’ represent just one lifestyle option for these adaptable rodents. What is unusual in Glasgow is the voles’ high population density and their proximity to urban life. Robyn leads us closer, carefully sticking to a path around the edge of the slope, which is honeycombed with burrows. It reminds me of walking near puffin colonies on the Isle of May or Farne Islands, where straying from the path could risk collapsing a burrow underfoot.
Robyn tells us that when Glasgow’s water voles were first discovered in grassland in 2008 – one accidentally caught in a trap set for rats – the initial response was a blanket ban on cutting of long grass. But in fact, properly managing the habitat of fossorial water voles means actively maintaining open grassy areas. Leave the grassland too long and it will become scrub and then woodland.
The team are currently trialling a new machine with exceptionally low ground pressure to cut the grass safely, taking small plots in rotation and leaving long grass nearby as a refuge. To learn more about how disturbance
“IN AN OTHERWISE NORMAL INNER-CITY PARK, I SEE MORE AND MORE BURROWS, AND WATER VOLES POPPING UP LIKE JACK-IN-THE-BOXES.”
affects the water voles, individually and as a colony, tiny radio transmitter collars will be fitted to monitor their behaviour and daily range.
During the summer breeding season, Robyn continues, the females use latrines to demarcate their territory. They scratch at scent glands on their flanks and then drum down on droppings with their hind legs to leave a signature scent for passing males. Females patrol their territory regularly, and the latrines can get quite large – a 20cm-long trail of brown sludge, often seen under a grassy tussock. Robyn has seen latrines as early as April, but not in 2018. Winter still had the year in its teeth and was not letting go.
This March and April the snow kept on coming, and postponed our visit a few times, but apparently it doesn’t trouble the water voles. Snow insulates their “wonderfully complex system of burrows”, and they’re snug underground with everything they need – indoor toilets, overwinter food stores and even spare bedding.
The chill drives us indoors for a lunch break, where Robyn and Laurie swap water vole stories, nodding in agreement about an intuition you develop, over time, that a certain patch of grass just “feels water vole-y”. Laurie remembers seeing water voles – or, more often, signs of their presence – when he was a child in the Scottish Borders exploring disused limekiln ponds in search of frogspawn, great-crested newts and dragonflies. The ponds were filled in when a new road was built, the rich wetland habitat was lost, and the water voles disappeared.
Laurie’s experience in Berwickshire is a microcosm of the wider UK story. A survey in the late 1990s showed that almost 90 per cent of the water vole population disappeared in 1989–1998, mostly due to habitat loss, exacerbated by predation by American mink.
GREENS AND GRASSLAND
Robyn wonders if we exaggerate the difference between riparian and fossorial lifestyles in water voles. After all, these are tenacious and highly adaptable small mammals that feed on a wide range of grasses and other vegetation (studies have identified 227 plant species in their diet). While they naturally are drawn to the rich vegetation around rivers, streams and pools, if there is no break in the habitat, they’ll happily spread into surrounding grasslands. All they need is good food and soft soil.
What has probably happened in Britain is that the land is so heavily managed, we’ve largely restricted water voles to the edge of watercourses. Fossorial water voles cling
SNOW POSTPONED OUR VISIT BUT IT DOESN’T TROUBLE THE WATER VOLES. THEY HAVE EVERYTHING THEY NEED UNDERGROUND TO STAY SNUG.
on in Glasgow, where they may have been for hundreds of years, and there are also some on a few islands in the Inner Hebrides. Could there be others? It’s likely that more fossorial populations exist elsewhere, unnoticed, because we only go looking for water voles near water.
Glasgow has ‘watery water voles’ too, in nearby wetlands, though we are not searching for those today. Our last port of call is a patch of green beside a housing estate, its slopes dotted with vole burrows and crowned with pigeon lofts, or ‘doocots’. The site has been earmarked for development and so ecologists have been brought in to move the resident voles to a new site. Water voles are a protected species and it is an offence to damage or disturb their habitat, but the team has a licence and know what they are doing. They carefully remove the turf, revealing the extensive network of tunnels just beneath.
A nearby householder stops to chat. He knows about the water voles – people used to think they were “big, black rats”, he says. But word’s got around that they are something special: a rare population of a nationally endangered species. He’s seen one pop up in his garden, he adds with a sense of pride.
Robyn says there’s mostly been a very positive reception to the Glasgow Water Vole Project. It involves a challenging mix of science and diplomacy: devising and managing research projects, and liaising with housing developers, residents, council officials and local schoolchildren – some of whom have water voles in their school playgrounds.
There’s a real commitment from all stakeholders to “get it right” Robyn says, for both water voles and people. “It’s all part of a growing acknowledgement that wildlife – and the wild – is not just in the far-flung reaches of the Highlands, but right here in Glasgow.”
Black ‘Ratty’ appears from a burrow in a Glasgow park. Non-aquatic water voles were discovered in the Greater Easterhouse area of the Scottish city in 2008, occupying urban grasslands in residential areas and along road verges.
Above: Glasgow’s glossy black water voles are among Britain’s most striking mammals. Below: the mole-like rodents pop up from complex burrow systems. Inset: ecologists use flags to mark the burrows.
Below right: this site in Glasgow has been earmarked for development. Ecologists have been called in to carefully expose the burrow system so the water voles can be trapped and relocated. Right: small traps are used to capture voles at the surface before moving them to a safer area of the park.
FOOD STORES enable the voles to stay below ground in winter and during adverse weather. They may comprise grasses, sedges, seeds and a range of other plant matter.
SOIL MOUNDS, disturbed earth and bolt holes are all clues to the presence of fossorial voles. They are less obvious or absent in winter.
NEST CHAMBERS at the heart of the burrow system are around 50–60cm deep, with tunnels radiating from them. Females have young in late spring and summer.
BURROWS can be quite complex systems and often stretch over 35m. They are all on one plane – tunnels don’t run under other tunnels.
OVERGROUND: THE VOLES THAT THINK THEY’RE MOLES
Glasgow has probably been home to water voles for hundreds of years but reliable records have only been kept in more recent times.
Left: Robyn Stewart of the Glasgow Water Vole Project sets a trap to relocate voles. Above: the protected rodents live right next to a busy path in this Glasgow park.