Black wa­ter voles

How ‘Ratty’ has colonised a Scot­tish city

BBC Wildlife Magazine - - Contents - ANNA LEVIN is an au­thor and for­mer sec­tion edi­tor of BBC Wildlife mag­a­zine; www.an­nalev­in­writ­ing.co.uk.

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.

ADAPTABLE RODENTS

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.

SNOWED IN

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.

SPE­CIAL NEIGH­BOURS

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.”

Pho­tos by Lau­rie Campbell

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.

UN­DER­GROUND,

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.

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