RATTY RE­TURNS

TALES OF THE RIVERBANK

World of Animals - - Front Page - Words Vic­to­ria Wil­liams

Dis­cover the se­crets be­hind the elu­sive wa­ter vole’s come­back

In 1929, Amer­i­can minks – rel­a­tives of weasels and ot­ters – were brought over to Bri­tain from North Amer­ica for the fur trade, but it wasn’t long be­fore some es­caped and oth­ers were il­le­gally re­leased. This in­va­sion was ab­so­lutely dis­as­trous for Bri­tain’s wa­ter voles, with one mink able to wipe out all the in­hab­i­tants along a stretch of riverbank in just a few weeks. While wa­ter voles can dive into streams or hide in their bur­rows to es­cape from larger na­tive preda­tors, these tac­tics did lit­tle to stop the ag­ile, semi­aquatic minks. Adding to the pres­sures of wa­ter pol­lu­tion and the degra­da­tion of river­banks, the ar­rival of the minks even­tu­ally led to a more than 90 per cent drop in wa­ter vole num­bers be­tween 1989 and 1998. In fact, wa­ter voles have ex­pe­ri­enced the big­gest de­cline of any Bri­tish mam­mal in the last cen­tury.

“The mink in­va­sion was ab­so­lutely dis­as­trous for Bri­tain’s wa­ter voles”

In re­sponse to the crash in their num­bers, con­ser­va­tion groups have re­dou­bled their ef­forts to save these en­dear­ing an­i­mals. The wildlife char­ity Peo­ple’s Trust for En­dan­gered Species (PTES) is ded­i­cated to help­ing wa­ter voles and has put more than half a mil­lion pounds into dozens of con­ser­va­tion pro­grammes since 1980.

These have in­volved look­ing into the best ways to re­store riverbank habi­tat, cap­tive breed­ing and rein­tro­duc­ing voles to ar­eas they used to in­habit, as well as in­ves­ti­gat­ing ways to con­trol mink pop­u­la­tions.

Emily Thomas, key species mon­i­tor­ing and data of­fi­cer for PTES, ex­plains why the char­ity is work­ing hard to pro­tect these strug­gling ro­dents. “Im­mor­talised as Ratty in The Wind in the Wil­lows, wa­ter voles are a key part of our nat­u­ral her­itage. They have been in Bri­tain since the last ice age and play an im­por­tant eco­log­i­cal role along our wa­ter­ways as an in­di­ca­tor of a healthy en­vi­ron­ment, pro­vid­ing food for a range of na­tive preda­tors and even af­fect­ing the bank­side plant di­ver­sity through the cre­ation of their bur­row net­works.”

When wa­ter voles dig bur­rows in a riverbank it dries out the sur­round­ing wet soil. This change pro­motes the ac­tiv­ity of mi­crobes in the soil, which al­ters the level of ni­tro­gen avail­able for plants to use and de­ter­mines which species can sur­vive in the area. As prey, wa­ter voles also pro­vide an im­por­tant source of food for birds like owls and herons, mam­mals in­clud­ing foxes, ot­ters and weasels, and even large fish such as pike. These lit­tle crit­ters are ab­so­lutely vi­tal to their ecosys­tems.

In 2015, PTES launched a new scheme to find out how Bri­tain’s wa­ter voles were re­ally do­ing. The Na­tional Wa­ter Vole Mon­i­tor­ing Pro­gramme (NWVMP) in­vites vol­un­teers from across Eng­land, Wales and Scot­land to go out each spring and mon­i­tor sites for signs of any wa­ter vole ac­tiv­ity. The chubby lit­tle an­i­mals are hard to spot, so mon­i­tors check for clues like drop­pings, feed­ing re­mains and bur­rows.

The data from the 2017 sur­vey has now been an­a­lysed, and Emily be­lieves that there are some pos­i­tives to be found in the re­sults. “The NWVMP aims to bring to­gether

“Im­mor­talised as Ratty in The Wind in the Wil­lows, wa­ter voles are a key part of our nat­u­ral her­itage”

“It’s only by con­tin­u­ally mon­i­tor­ing sites an­nu­ally that we’ll be able to get a com­pre­hen­sive idea of how wa­ter voles are far­ing across the coun­try”

all cur­rent mon­i­tor­ing, as well as resur­vey sites from the pre­vi­ous na­tional sur­veys so we can find out what the cur­rent sit­u­a­tion is and de­tect any fu­ture changes. Last year, we re­ceived data from 222 sites across Bri­tain, of which 82 had ac­tive wa­ter vole signs (la­trines, feed­ing signs or sight­ings) present at them. 130 sites were sur­veyed in Eng­land, 78 in Scot­land and 14 in Wales. Of the pos­i­tive sites, 56 were in Eng­land, 15 were in Scot­land and 11 were in Wales.

The dis­tri­bu­tion of these pos­i­tive sites was very en­cour­ag­ing, with sites rang­ing from Corn­wall and Suf­folk up to the High­lands and across to the Isle of An­gle­sey.”

Many of the pos­i­tive sight­ings came from sur­veys con­ducted in na­ture re­serves or rein­tro­duc­tion ar­eas.

Ac­cord­ing to Emily, PTES is still hop­ing to gather data from vol­un­teers in even more lo­ca­tions, es­pe­cially in the South West, the West Mid­lands, south­ern Scot­land and Wales.

“The pre­vi­ous na­tional sur­vey sites were specif­i­cally se­lected to give a good ge­o­graph­i­cal spread across Bri­tain, en­sur­ing all habi­tats and ar­eas were sur­veyed. By the 1996–98 sur­veys, many of them no longer had wa­ter voles present, and so it’s un­sur­pris­ing that wa­ter vole

oc­cu­pancy at these sites is still low. How­ever, we know from the first na­tional sur­vey that many of these sites sup­ported wa­ter voles 25 years ago; there­fore some should have the po­ten­tial to sup­port the species in the fu­ture.

“Mink con­trol con­tin­ues and habi­tat con­di­tions keep im­prov­ing, there­fore the longterm aim of the mon­i­tor­ing pro­gramme is to con­tinue to sur­vey these his­toric sites an­nu­ally in the hope that wa­ter voles will re­colonise them. Once again, we’ll be aim­ing to in­crease the num­ber of sites sur­veyed [in 2018] so we can con­tinue to col­lect ro­bust data to de­ter­mine yearon-year trends.

“It’s only by con­tin­u­ally mon­i­tor­ing sites an­nu­ally that we’ll be able to get a com­pre­hen­sive idea of how wa­ter voles are far­ing across the coun­try.”

In pre­vi­ous years the sur­vey has run through May, but PTES are ex­tend­ing the win­dow this year so that data can be col­lected be­tween mid-April and mid-June. Re­cent mild win­ters have en­cour­aged riverbank plants to grow thick ear­lier than usual, so the ear­lier start gives vol­un­teers look­ing for the shy voles a bit of a head start. It’s vi­tal to the pro­gramme but, as Emily ex­plains, the sur­vey­ing isn’t too time con­sum­ing.

“Vol­un­teers are asked to sur­vey one of the nearly 900 pre-se­lected sites across Bri­tain, record­ing all sight­ings and signs of wa­ter voles along a 500-me­tre [1,640.4-foot] length of riverbank from mid-April to mid-June. Sites that are al­ready be­ing sur­veyed can also be regis­tered with the NWVMP. Though no prior ex­pe­ri­ence is re­quired, vol­un­teers will need to learn how to iden­tify wa­ter vole field signs.”

To find out more, or to regis­ter as a vol­un­teer for PTES’s 2018 Na­tional Wa­ter Vole Mon­i­tor­ing Pro­gramme, visit:

www.ptes.org/wa­ter­v­oles

“The pro­gramme in­vites vol­un­teers to mon­i­tor sites for signs of wa­ter vole ac­tiv­ity”

be­low Wa­ter voles are shy crea­tures, usu­ally van­ish­ing into the wa­ter if they hear any­one ap­proach­ing

If vol­un­teers don’t

spot the voles them­selves, they look for signs that they live

in the sur­vey area

Wa­ter voles chew their food at an an­gle, leav­ing be­hind dis­tinc­tive piles of nib­bled stems when they feed

Div­ing into a stream doesn’t pro­tect wa­ter voles from minks be­cause the preda­tors are strong swim­mers

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