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.

When undertaking 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 supervision.

There is a link to the Natural England Water Vole documents on the Links Page.

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For a no obligation chat about your requirements call Dave Bentley Ecology Services on 0161 478 6594 or 07598 742566. We are here to help. Email info1@davebentleyecology.co.uk. If you are sending large files please send them to big2@dave...... In the case of over quota bounce-backs try "big2" before the @ symbol. We are a Bury-based ecological consultancy. 35 years experience in nature conservation!!



Text and images copyright of Dave Bentley 2007 & 2011. Banner panorama photo H Groth-Andersen 2006.

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