Tuesday, 19 May 2015

How to spot a Water Vole

While everyone was enjoying the summer sun this weekend I was attending a Water Vole identification workshop in Cambridge. Why was this course so important? Well, here at Holkham NNR we are in the process of recording and surveying the Water Vole population. This is very important because since the 1970s there has been a 90% decline in Water Voles and they are now considered one of the most endangered and fastest declining wild mammals in the UK. They are threatened by habitat loss and particularly from predation by the introduced American Mink.

As part of the course we searched under
 bridges in the area looking for signs of Mink, 
Otter and Water Vole

Water Voles are very secretive, so the best way to find them is to look for signs of activity – feeding stations, latrines, burrows, footprints and paths.

Feeding stations – These can be spotted by the ‘lawn’ effect. They are most noticeable in summer when reeds, sedges and neatly chopped grasses, often cut at a characteristic 45 degree angle, can be seen at a few selected places close to burrow entrances. Water Voles need to eat 80% of their body weight every day, so a lot of time is spent feeding!

Holkham has lots of dykes, ideal habitat for
 these little critters.

Latrines - As with all mammals (and some visitors to the reserve!) poo is an ever-present sign of activity. Latrines are often located a short distance from feeding stations and burrows and are also used to mark territory.

In summer Water Voles feed on green vegetation making
 their droppings greenish, but in winter when they eat bark, 
roots and other plant material so their droppings are brown.

Burrows – Water Voles burrow into banks and form extensive and complicated tunnel systems. These can be on several levels to minimise the risk of flooding and at least one entrance will be below the surface of the water, for a fast escape if needed. If you stand quietly, you might hear their distinctive ‘plop’ as they dive into the water.

Unlike rats, Water Voles don't leave loose soil in front of
 their burrows.

Footprints in soft mud - It takes a keen eye and a lot of practice to spot Water Vole footprints. Their forefeet leave a distinctive star-shaped footprint. A slow Water Vole is a dead Water Vole – these little animals have runways through bank side vegetation, which they use to avoid avian predators and in autumn to carry food to the burrows for winter.

Water Vole tracks are 20-25mm long.

Water Voles have poor eyesight but their whiskers pick up the slightest vibration. If you are trying to see them, remain quiet and very still near a suitable steep-sided dyke with plenty of vegetation, and if you are lucky you might see a Water Vole swim past you.

This is the best photo we have managed to get of the 
elusive creature! Can you do any better? 

The Water Vole is a much-loved creature and is often remembered as ‘Ratty' in Kenneth Grahame’s classic children’s book, The Wind in the Willows. With no mink on the reserve let’s hope Holkham NNR has a good population of Water Voles, I’ll keep you informed!

Happy Hunting

Jonathan Holt
Holkham Warden