| Water Vole - South West |
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The water vole is found throughout mainland Britain occupying riparian habitat. However a national survey 1989-90 demonstrated that the population has apparently been lost from three quarters of the sites it occupied before 1939, with a predicted total loss of 94% of its former sites by the year 2000. The rate of site loss appears to have accelerated through the late 1980s and early 1990s. The last strongholds for the species occur in southern and eastern England. It is listed in the UK Biodiversity Steering Group Report as a priority species for conservation. Proposals for inclusion of the water vole in schedule 5 of the Wildlife and Countryside Act 1981 are currently under view (to be amended 1997). In the 1989-90 survey the water vole was found to be scarce or rare over much of the South West region occupying 95 out of 295 sites visited (32.2%) Regional distribution in the South West1
Priority
Areas and natural areas in the South West1
Basic Management requirements1 Relevant Ecology Water Voles are the largest of the British Voles, adults attaining a body weight of weight between 200 and 350g. They are herbivorous, primarily feeding on the lush waterside vegetation of sedges, rushes and reeds. In the winter months, roots and bark of shrubs and trees form an important part of the diet together with rhizomes, bulbs and roots of plants (which may be collected into stores in the voles' underground tunnels). Each vole utilises a series of burrows dug into the riverbank where the soil permits (i.e. not gravel bed or rock strata). These include residential burrows- comprising many entrances, inter-connecting tunnels and nest chambers - and bolt-holes consisting of short tunnels ending in a single chamber. Nest chambers occur at various levels in the steepest part of the bank and the nest consists of shredded grass. Occasionally the animal will weave a nest into the bases of sedges and reeds. Breeding occurs from March to October, and females may produce two to five litters annually, each of five to eight young. July-born young may breed that autumn, but most reach sexual maturity after the first winter. Exceptionally, water voles may survive three winters but mortality
is thought to be very high amongst dispersing juveniles. Water voles favour a slow-flowing water course, less than 3m wide, around 1m in depth and not showing extreme fluctuations in water level. Permanent water is essential during periods of low flow in summer, while sites that suffer total submersion during protracted periods of winter flooding are untenable. Shore type is predominantly earth (rather than gravel or rocks) with a bank profile that shows a stepped steep incline which the voles can burrow and create nest chambers above the water table. The amount of bankside and emergent vegetation cover is very important with the best sites offering a continuous swathe of tall and luxuriant riparian plants (at least 60% ground cover). Sites excessively shaded by shrubs or trees are less favoured.
Habitat type Reed beds, sedge beds, stands of emergents, and riverbank vegetation are essential for a self-sustaining water vole population Grazing Excessive over-grazing by sheep, cattle and horses not only reduces the amount of food and cover for the voles, but the poaching of the ground at the water's edge makes the site untenable by compacting the soil and damaging the burrow system. At such sites it is recommended that the bank is fenced or at least partially fenced to provide refuges for water voles. Mowing If mowing of the river bank is deemed necessary, area of uncut vegetation can be left, perhaps as patches of varying length at close intervals. This can be done on opposite banks or one bank can be left uncut. By altering he cutting regime annually, woody scrub will be prevented but sufficient food and cover will be left for water voles. A 2 m band of bank cover in patches of 20-50m would be ideal. River channel management Where river channel management is required, dredging from one bank only is recommended, in line with current good practice. In most instances, it should be possible to leave stands and/or marginal fringes of emergent vegetation during de-silting operations in order to retain valuable habitat for water voles. River Maintenance River maintenance operations should normally leave banks untouched, but where bank re-grading is deemed necessary, this should be of a profile which maximises the width of marginal vegetation that can re-establish itself. The bank profile could be stepped, or have a steeper incline on the upper half of the bank, to facilitate burrowing. Any bank re-grading should be restricted to small sections as much as possible; it is preferable to retain existing bank profiles, particularly if well vegetated. Nearby waterways or lateral channels should be left untouched as a refuge site. Particular care should be taken when excavating and re-dredging adjacent ditches, small streams and lateral channels as there are important features for the local water vole population River Bank Reinforcement Where bank erosion requires bank reinforcement, the use of sheet metal pilling rock gabions or masonry should be avoided at water vole sites. Sympathetic bank maintenance should be encouraged by way of small-scale repairs or through the use of living willow withies, coir fibre bundles or other natural materials which will allow the bank to be used by water voles following repair. Mink Control At a few vulnerable sites it may be necessary to control mink numbers. Removal of female mink by live capture in cage traps is recommended in the months of February, March and April, This will reduce hunting pressure put on the site by female mink rearing young.
Current
Factors affecting the species1
South West biodiversity objectives and proposed targets 1 OBJECTIVE 1 Halt the decline in number of water voles within their current range in the South West region. TARGET: ongoing OBJECTIVE 2 OBJECTIVE 3 OBJECTIVE 4 OBJECTIVE 5
National: A full UK Species Action Plan has been prepared on behalf
of the Water Vole Steering Group and is consistent with the UK Biodiversity
Action Plan. This species is being considered for inclusion on schedule
5 of the Wildlife and Countryside Act 1981. To date, direct conservation action taken for the water vole has been
limited, although a number of practical conservation measures have been
investigated, including habitat enhancements as part of flood defence
work carried out by the Environment Agency. These have helped to maintain
existing water vole populations at some sites, especially through the
restoration of suitable habitat (ponds old oxbows, backwater channels
and floodplain ditches). MAFF's Agri-environment schemes (e.g. Habitat Scheme, Countryside Stewardship and ESAs) affecting riparian zone habitat offer opportunities to maintain existing water vole populations Water Vole actions are included in the relevant Local Environment Agency Plans (best practice guidelines are being developed). Water Vole actions are included in relevant nature reserve management plans by English Nature and the Wildlife Trusts. Proposed Action 1 Policy and legislation
Identify core populations of water voles in the region and seek to retain these with appropriate management and monitoring. A series of 'key sites' should be designated from NNRs, SSSIs or other wildlife sites. (By 1998) LEAD: WTs
LEAD: EA Promote sensitive habitat management for water voles through Agri-environment schemes (ongoing) LEAD: MAFF PARTNERS: ADAS, FWAG Using survey and research information, identify sites which are suitable for re-establishing populations (by 1998) LEAD: WTs PARTNERS: EN, EA, MS Ensure that development schemes do not affect the integrity of
water vole populations Management
Investigate the efficacy of mink control as a conservation
tool at core water vole populations (by 1999) Establish a co-ordinated programme of translocation and re-introductions where it is deemed appropriate and effective (by 2010) LEAD: EN
LEAD: WTs, EA
LEAD: EN Research and monitoring
Undertake detailed catchment based surveys in the region to determine the extent of the water vole populations and level of fragmentation (by 1998) LEAD: WTs Following existing and new national research initiatives on the ecology and conservation requirements of water voles, apply recommendations to local populations (by 2010) LEAD: EN PARTNERS: EA, WTs, Universities Encourage the submission to JNCC or ERC of data collated on a local level for incorporation into a national database, and to facilitate easier access to information LEAD:RCs Education and awareness raising
Establish a regional water vole forum/ working group to improve
communication between all those involved in water vole conservation
(by 1997) Encourage the publication of research papers and features in popular press, magazines and the broadcast media to raise the profile of the species LEAD: WTs, EA
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