Wild Encounters#4: Arvicola amphibius

18th August 2017

Water Vole by Peter Trimming. Image from Flickr licensed under Creative Common

I walked barefoot along the board walk early one summer morning, trying to creep up one of Britain’s rarest mammals.  At this time of day, I had Malham Tarn to myself, so my ears were straining above the hum of insects and songs of birds, to hear a watery splash.  That was what had alerted me to its presence when I visited the nature reserve last summer, but today the slow moving streams were almost silent.  I peered into the clear water which runs into England’s highest freshwater lake, but only the underwater reeds were stirring.

The water vole is Britain’s fastest declining wild mammal and has disappeared from 90% of streams and rivers where they once lived.  Much loved as the loyal ‘Ratty’ in Wind in the Willows, the water vole is another British mammal that seems to pop up in story books, but is hardly ever seen, due to the combined threat of loss of habitat, pollution and attacks from introduced American mink.  However at Malham Tarn the species is making a comeback, thanks to a reintroduction scheme being undertaken by the National Trust.  Two hundred water voles have been released over a two year period, and now the animal is thriving in its new home, with some animals spreading up to a kilometre from the original introduction site.  As well as helping to conserve the endangered species, the reintroduction of the water voles is enabling the restoration of the fenland habitat, which will benefit other species such as fish and invertebrates too.

It wasn’t my first visit to Malham Tarn to catch site of the water vole.  After accidentally coming across one the summer before, I was keen to see more, and a friend and I had visited the nature reserve with our children a month earlier.  The girls watched patiently from the bridges over the streams, but saw nothing but a lone fish.  There were signs of water vole poo on the feeding platforms close to the release sites and what looked like a burrow in the banking, but no water voles.  “You should have been here earlier. I saw one this morning”, a ranger told us, in what is becoming a familiar comment in my quest to encounter British wildlife for my blog.

Determined, I returned on my own early one August morning and took my time to watch and listen. With no one hurrying me ahead, I walked slowly and enjoyed the range of wetland wild flowers that grow either side of the board walk, including marsh orchids and the tiny carnivorous sundew plant. Leaning on the bridge and listening to bird song I was suddenly aware of a rustling in the vegetation.  I focused my attention I realised something was chomping at the grasses and doing so with some heart.  Apparently water voles consume around 80% of their body weight in food everyday, so it seemed likely this was what I was hearing.  I stayed a while hoping to catch a glimpse but it was busy about its business of eating, hidden deep in the undergrowth.  I listened for a good twenty minutes, recording the munching on video, when suddenly, disturbed by the footsteps of a new visitor on the board walk, there was a distinct plop as it dropped into the water.  I caught a brief site of its sleek body swim across the stream and into a burrow.  Too quick to catch on camera, but a wonderful brief encounter with another rare sample of British Wildlife.