Why do water voles need my help?

Since the 1980s the water vole (Arvicola amphibious) has undergone one of the most catastrophic declines of a species ever known in the UK; for example, over the 1990s they were lost from 94% of sites they had occupied, and their population is now a tiny fraction of what it was 50 years ago. The main reasons for this decline are predation by mink coupled with habitat fragmentation and associated population isolation. While a great deal of effort has been put into habitat protection and management for water voles, there is an urgent need to expand co-ordinated control of mink.

A water voles defensive strategy is to dive then swim underwater to a burrow entrance, sometimes kicking up silt to create a “smoke screen”. This is an effective trick against usual predators such as a fox, stoat or heron but unfortunately the mink can swim more strongly, faster and can smell underwater making this strategy ineffective. To make matters worse, female and juvenile mink are small enough to enter a water voles burrow; this can be catastrophic during the winter because all the voles surviving winter are the breeding population. A water vole colony can be wiped out in a year!

East Anglia is known to be a stronghold for water voles with the Norfolk Broads holding a high population on the River Ant and in Broadland dykes. Other important areas include the fens in the extreme west of the county, the north Norfolk coast, the River Wensum and the south Norfolk claylands.

How do I recognise a water vole?

A water vole can be easily confused with a rat, so note that a water vole has hairy ears, paws and tail but a rat has pink ears, paws and a longer, scaly tail. Here are a few more tips on how to recognise a water vole.

  • Size of a small rat, female 12-15cm, 100-250g. male 15-20cm, 250-300g.
  • Chestnut brown fur, short, rounded hairy ears (almost hidden by fur), hairy paws with a hairy tail.
  • Blunt snout & round, ‘chubby’ face with tiny, ‘beady’ eyes.
  • Swimming: body shows, doggy paddle, dives with “plop”.
  • Breed up to 5 litters / year Apr-Sep, up to 5-6 young, social in winter.
  • Food vegetarian, reeds, grass, leaves, roots.

© Snake Meadow Fisheries

© Jakie Dent

Click an image to enlarge.

How do I know if a water vole is present?

Burrows

A water vole excavates a narrow burrow at, below, or just above the water line; this will be nice and neat, often with no excavated earth at the entrance. A rat’s burrow will be slightly larger and are not always at the water’s edge. A rat will often leave a heap of excavated earth at the entrance and form heavily trampled runs, forming a network connecting to various burrows.

Droppings and latrines

Water vole droppings are the most reliable field sign for indicating their presence. The droppings are cylindrical, 10-12 mm long (shorter for young) and often rounded at both ends. They are odourless, varying in colour from bright green, brown, grey or even purplish when fresh, darker when dry. Droppings left in neat piles are called ‘latrines’; these indicate territories, which are established during February- November. Latrines are usually at or near the water’s edge, and may be on bare mud near the entrance to a burrow.

Click an image to enlarge.

Feeding Stations

Neat piles of chopped lengths of vegetation, mostly about 10cm or so long and with a 45 degree angle cut to each end are a good sign that water roles are present. If you can only find old vegetation which has been cut by a water vole, it does not mean the water vole is still present. If this is the case you then need to find signs of droppings, if you cannot find fresh vegetation or droppings the water vole may no longer be there. Only green vegetation can be taken as a recent sign of water vole presence.

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This information and more about water voles can be found on our Guidance Documents page, document “Water vole species information”, “Mammal differences” and “Footprint identification” goes into more detail with lots of useful tips.