Examples of two rehabilitation projects with which we have been involved are given below:

Pagham Harbour -

The Pagham Harbour project developed by the Chichester Costal Plain Sustainable Farming Partnership affords an excellent example of a joined up approach to habitat management of significant benefit to water voles and a range of associated wildlife.

The project area operated over 42 farms totalling 8,400 ha. Advice on grant funding and provision of a whole farm conservation plan helped farmers to achieve benefits and maintain sustainable farms. These agreements restored 27 farm ponds, created 28 ditch-junction ponds and maintained water in 42 km of ditches through the summer months by the installation of sluices or bunds. 7,200m of fencing was erected to protect water courses from livestock and 6 meter margins of buffer vegetation were retained along targeted water courses to create habitat corridors. In addition to the forgoing the management of 83 km of statutory watercourse running through the farmed land was reviewed. 26 km continued to be managed intensively while 57 km was placed in a regime where only mid channel vegetation or bank vegetation on one side was removed. This measure ensured year round food and cover for water voles.

Water voles within the project area in 2000 were scarce and highly fragmented. They were largely confined to small number of farm ditches or ponds. The total population was estimated at about 100 individuals – a late summer figure that also included juveniles.

By 2003 the population had tripled in size and with an additional input of captive bred animals; they are currently believed to inhabit virtually all the suitable habitat in the project area. Mink trapping was undertaken as a component part of this process using traps initially and rafts at a latter stage. Within the period of the project mink were eliminated from the catchment and this collaborative concept is now being developed on a larger project area of 27,000 ha in the upper Thames.

Cattle impacts on bankside vegetation offer little cover for voles

Water voles will be reintroduced in significant numbers into this landscape by the Wildlife and Conservation Research Unit of Oxford University (WildCRU). The first release of 200 animals occurred in 2005 and although it is too early to project the long term outcome dispersal from the initial populations has gone well, survival rates for released adults are good and successful reproduction has been recorded.

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Barn Elms -

In the summer of 2001, 106 captive-bred and 36 translocated water voles were released into the grounds of the Wildfowl and Wetlands Trusts Centre at Barn Elms. Barn Elms is a 105 acre wetland created around the site of a former Victorian reservoir 4 miles from the centre of London. The habitat mosaic of large wet meadows, pools and reed beds was believed to be ideal for water voles. No mink were present on the site and access for this predator was believed to be very difficult due to extensive surrounding conurbations. It was estimated that between 30-40 of these animals plus their juvenile offspring from 2001 were extant on site at the beginning of the breeding season of 2002.

The initial release population was therefore supplemented in April 2002 with another 50 over-wintered juveniles and the water voles then spread rapidly throughout the reserve. Trapping in October of 2001 for 3 weeks captured 57 animals. Only 30% of these were pre-June released animals, 54% were June released animals and 72% were July released animals. All were of good weight and if transpondered had on average remained within 500 meters of their original release site. 21 animals were 60–200 grams in weight without transponders and had probably been born from July onwards.

By the beginning of 2005 it was apparent that the water vole population had suffered a significant restriction of range and were only inhabiting one main part of the reserve so further animals were released to supplement the population. Although site surveys are still to be undertaken for 2006 it may be the case that further supplementation is required.
Why should this have happened in good habitat without mink predation?

Release Pen

The possible causes although not clear may be a compilation of the following concentrated Grey heron (Ardea cinerea) predation in a limited area with a large number of birds focused on feeding in a single site; the original genetic integrity of the water vole population which was drawn from only 3 founder populations, the limited availability of over-wintering habitat on site and the inability due to an absence of suitable surrounding habitat of the population to establish satellite colonies what can then exchange with the central founder population.

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