Water Vole Reintroduction on the Gwent Levels, Wales, UK

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Published by: IUCN/SSC Reintroduction Specialist Group & Environment Agency-Abu Dhabi

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Citation: Soorae, P. S. (ed.) (2018). Global Reintroduction Perspectives: 2018. Case studies from around the globe. IUCN/SSC Reintroduction Specialist Group, Gland, Switzerland and Environment Agency, Abu Dhabi, UAE. xiv + 286pp.

6th Edition

ISBN: 978-2-8317-1901-6 (PDF) 978-2-8317-1902-3 (print edition)

DOI: https://doi.org/10.2305/IUCN.CH.2018.08.en

Cover photo: Clockwise starting from top-left: I. Reticulated python, Singapore © ACRES II. Trout cod, Australia © Gunther Schmida (Murray-Darling Basin Authority) III. Yellow-spotted mountain newt, Iran © M. Sharifi IV. Scimitar-horned oryx, Chad © Justin Chuven V. Oregon silverspot butterfly, USA © U.S. Fish and Wildlife Service VI. Two-colored cymbidium orchid, Singapore © Tim Wing Yam VII. Mauritius fody, Mauritius © Jacques de Spéville

Cover design & layout by: Pritpal S. Soorae, IUCN/SSC Reintroduction Specialist Group

Printed by: Arafah Printing Press LLC, Abu Dhabi, UAE

Download at: www.iucnsscrsg.org www.iucn.org/resources/publications

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Water vole reintroduction on the Gwent Levels, Wales, UK

Alice Rees

Water Vole Project Officer, Gwent Wildlife Trust, Seddon House, Dingestow, Monmouthshire, NP25 4DY, UK [email protected]

Introduction The European water vole (Arvicola amphibius) is a semi-aquatic member of the Rodent family. They are vegetarian and inhabit watercourses ranging from rivers and lakes to ditches and ponds. They build complex burrow systems within the banks of watercourses and act as ecosystem engineers, creating niche habitats for other species to live. In Britain, water voles are protected under the Wildlife and Countryside Act 1981 (as amended). They are in decline in the UK and are classed as a Priority Species in the UK Biodiversity Action Plan. The Gwent Levels is a south Wales estuarine landscape, rich in both historical and natural heritage. It sits in the southeast corner of Wales on the north side of the Severn estuary between Cardiff in the west and Chepstow in the east. Gwent Wildlife Trust’s nature reserve Magor Marsh is where the water voles were released, and is the last relatively natural area of fenland on the Gwent Levels.

Goals Goal 1: The establishment of a successful American mink control network on the Gwent Levels. Goal 2: The restoration of a viable water vole meta-population on the Gwent Levels.

Success Indicators Indicator 1: Water voles spread from release site into wider landscape. Indicator 2: The resident American mink population is reduced or removed.

Project Summary Feasibility: Water voles were once an intrinsic part of the Gwent Levels. The introduction of the invasive non-native American mink (Neovison vison) in the 1950s onwards meant the population crashed, as reflected across the UK. In 2011, Gwent Wildlife Trust conducted a pilot project to assess feasibility for a European water vole © Andy Karran water vole reintroduction

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at Magor Marsh Nature Reserve. We ascertained that the most recent record of a water vole in the area was 2003 and despite yearly surveys, no other records were found since. Desk studies also revealed no likely nearby populations. Since 2006 American mink control had been happening on our Magor Marsh Nature Reserve on the Gwent Levels. With large areas of suitable habitat available, American mink were certainly the cause of the decline in water voles in the area. Magor Marsh is a Site of Special Scientific Interest and we have been managing it in favor of wildlife for over 55 years. We have approximately 4.5 km of suitable ditches at Magor Marsh with more suitable habitat in the area around the reserve. We also made sure there were sufficient animals available for us to release from the breeding facility. All of these points gave us confidence that Magor Marsh was an extremely suitable reintroduction site for water voles. Water vole survey © David Lucas Implementation: Gwent Wildlife Trust already had an established American mink trapping program at Magor Marsh Nature Reserve. In 2011 - 2012, we extended the trapping to a wider area around the reserve. This not only caught animals in a wider area but also served as an early warning or surveillance system so we could quickly detect any new mink who entered the zone before they reached Magor Marsh. This proved successful and so in 2013 we released over 200 water voles on to Magor Marsh Reserve. These were captive-bred animals who had been properly health screened before release. We were also certain that the animals were of genetic stock suitable to lowland conditions (as opposed to water voles from the highlands). We used a soft release method to gently introduce them to their new surroundings. We released water voles in several stages, to mimic the natural colonization of the area.

Post-release monitoring: Gwent Wildlife Trust survey the same 10 ditches twice a year on Magor Marsh Reserve to monitor the population. We follow the standard methodology found in The Water Vole Handbook (Strachan et al., 2011) and survey 200 m of each ditch to search for water vole field signs including burrows, droppings, feeding remains such as chewed grass, and the animals themselves. Our monitoring shows the water voles are thriving. Surveys completed in areas around Magor Marsh in the wider landscape show the water voles have spread over 10 km away. We continue to trap and monitor for mink, and these show that the mink have remained at low density. It is likely we have

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eradicated the resident population and are now only seeing migrating individuals coming in from other areas.

Major difficulties faced Demonstrating the importance of American mink control to counter the negative perception some members of the public have.

Major lessons learned Success depends on high input from volunteers to monitor for mink and help us complete water vole surveys. Success depends on setting up an American mink control program well before water voles are released, with proven evidence that mink numbers are low. American mink control is an on-going commitment, anyone undertaking a water vole release will need to commit to long-term mink control. Success depends on having enough suitable habitat available with good connectivity to other good habitat elsewhere. This enables the establishment of a large robust meta-population which is better able to withstand localized extinction events (such as flooding).

Success of project

Highly Successful Successful Partially Successful Failure √

Reason(s) for success/failure: The water voles have established a thriving population within Magor Marsh and also throughout the wider landscape around the reserve leading to a resilient meta-population. We have engaged with several different partners which has led to a larger Landscape Scale partnership looking at diverse ecological issues across the Gwent Levels. We have successfully engaged with and educated lots of different people in wildlife and water voles helping protect wildlife for the future. We prepared for the reintroduction for several years, establishing a good mink control program well in advance.

References Strachan, R., Moorhouse, T. & Gelling, M. (2011) The Water Vole Conservation Handbook (3rd ed.). Pulished by Wild cru.

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