Water Vole Survey and Mitigation in North West England
A survey for Water Voles involves searches for burrows, aerial nests,
droppings, latrines, feeding stations (fresh and old), runs and lawns. A pond
net is invaluable for locating droppings amongst flooded vegetation. Signs of`
Water Voles can vary from numerous latrines and feeding stations to a single
dropping taken in a pond net. Often it is necessary to wade out to floating
rafts of vegetation where the signs will be found - signs are in no way
restricted to bank edges. At several sites Dave Bentley has located Water Voles
missed by other consultants in the same season. This is due to most pond
surveys nowadays being limited to the rather mechanical and skill-less
bottle-trap survey and torch survey for Great Crested Newts. At urban Water
Vole sites it may be possible to locate a nest by for example lifting rubbish -
at one site baby voles were found under a foam cushion on a floating sofa, and
at another under a block of rubble. Urban edge sites tipped with rubbish should not be dismissed. Latrines are frequently found on tipped items.
It is necessary to be able to confidently distinguish between the signs
of Brown Rat and Water Voles. Brown Rats leave black, often pointed droppings
which are quite smelly and putty-like in the fingers. Both leave droppings
singly or in latrines. Water Vole droppings are usually made of vegetation,
have a greenish or brown colour, blunt ends, and smell of grass, having an
associated lighter texture, often crumbly when dry. Their size is about 8 to 15mm long by 4 to 5 (6) mm wide. It is also necessary to discount signs left by
smaller mammals such as Field Voles which consume finer grasses – where fine
chopped grasses are found these signs should be discounted. Field Voles also leave
much smaller droppings (at most 2mm wide compared with the 4-5mm width of the
Water Vole though they are often 8mm in length). Beware droppings swollen by
water which can be misleading. At least one site in Bury was given additional
protection due to an erroneous Consultant's report recording swollen Field Vole
droppings as those of Water Voles.
Water Voles are in no way
restricted to occupying streams and ditches. Two thirds of Dave Bentley's 90
Water Vole records are from ponds and marshes. Water Voles spend time
collecting food, eating part of it, and leaving part in piles. Fresh remains obviously
contain green plant material. Sometimes food remains from the previous year are
found. At one site the previous year's food piles were located in a Common Reed
reedbed - these being the hard tips of Common Reed shoots, a plant which has
new leaves which are rolled so densely they are discarded by the animal, though
the softer lower stem growth is eaten. The shoots were stacked together and
clearly felled (by virtue of the tooth marks). At a diameter of 6mm the stems
were too thick and firm to be the remains of other small mammals such as Field
Voles. These finds proved important in showing that the reedbed was used by
Water Voles later in the year when the Common Reed growth was denser.
Water Voles are identified by specific Water Vole
Surveys, or through single visit Pond Biodiversity Surveys or via rapid blanket
pond surveys undertaken for example for Great Crested Newts.
Water Vole exclusions schemes, for example from pipeline routes, it is most
important to remove all the vegetation back to bare earth by strimming about 4
weeks beforehand and keep the vegetation out by repeat-strimming every week.
The vegetation should be removed from both the banks and the watercourse, in
the latter case by strimming or dragging with a muck rake. Piles of cut
vegetation must be removed from the clearance area and placed further down the
bank where the piles may provide alternative refuges for Water Voles. Potential
nesting sites should be monitored and removed once the young depart.
Water Vole usage of particular sites will change over the year as different stands of vegetation grow up and provide food for them. Additionally when the young Water Voles depart their birth burrow they seek out their own territories and these may initially be sub-optimal habitats and these may only be occupied for part of a year. Thus it is important not to lightly dismiss habitats as not being suitable for Water Voles. Water Voles may be absent one month but present the next month.
Dave Bentley Ecology
Services is able to offer a full Water Vole service including survey, impact
assessment, mitigation design, and practical mitigation work and ecological
There is a link to
the Natural England Water Vole documents on the Links Page.
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