As considered in Part 1: Legal Considerations and Planning Works, water vole and its habitat are protected and as such precautions need to be taken when planning and undertaking any works affecting aquatic habitat.
A detailed Mitigation Strategy should be developed for any site where proposed works will unavoidably affect water vole and/or its habitat. This strategy would consider the options available based on the survey results, proposed works and site conditions and set out a Precautionary Method of Working and may include: habitat creation and enhancement, habitat manipulation, phasing of works, sensitive timing and presence of an Ecological Clerk of Works.
Part 2: Implementing Works Affecting Water Vole Habitat
Part 2 of this Blog considers the displacement method in more detail, which is Ecosulis’s preferred method of mitigation where water voles are present and avoidance is not possible.
The benefits of the displacement method are:
- It is relatively quick to implement (on average takes 5-7 days)
- It is relatively cost effective
- It does not require a licence (i.e. no water voles are to be captured or translocated)
However, the downsides are:
- Implementation work is restricted to between late-February and early-April
- It is generally only considered appropriate for works affecting 50m of bankside habitat or less (up to 100m in some instances)
Prior to the implementation of any mitigation a detailed Precautionary Method of Working should be compiled by an experienced ecologist based upon survey data and outlining an appropriate method. However, broadly the water vole displacement method includes:
- Provision or enhancement of alternative habitat
- Identification of all burrows
- Phased cutting of bankside and in channel vegetation
- Monitoring and removal of territorial markings
- Careful hand excavation of burrows
- Topsoil removal
- Further monitoring
Where there is a delay between the implementation of this mitigation method then the use of water vole fencing may also be recommended alongside on-going vegetation management and monitoring.
Projects where Ecosulis has implemented the displacement method have proven successful on the basis that:
- No water voles have been encountered during the destructive searches; and,
- Short and long-term monitoring has shown the continued use of the sites by water voles with no apparent significant changes in population size.
Further useful reading
Strachan, R (2006). Water Vole Conservation Handbook. The Environment Agency and The Wildlife Conservation Research Unit, Oxford. Second Edition