Beavers in Scotland a Report to the Scottish Government Beavers in Scotland: a Report to the Scottish Government
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Beavers in Scotland A Report to the Scottish Government Beavers in Scotland: A report to the Scottish Government Edited by: Martin Gaywood SNH authors (in report section order): Martin Gaywood, Andrew Stringer, Duncan Blake, Jeanette Hall, Mary Hennessy, Angus Tree, David Genney, Iain Macdonald, Athayde Tonhasca, Colin Bean, John McKinnell, Simon Cohen, Robert Raynor, Paul Watkinson, David Bale, Karen Taylor, James Scott, Sally Blyth Scottish Natural Heritage, Inverness. June 2015 ISBN 978-1-78391-363-3 Please see the acknowledgements section for details of other contributors. For more information go to www.snh.gov.uk/beavers-in-scotland or contact [email protected] Beavers in Scotland A Report to the Scottish Government Foreword Beavers in Scotland I am delighted to present this report to Scottish Ministers. It is the culmination of many years of dedicated research, investigation and discussion. The report draws on 20 years of work on beavers in Scotland, as well as experience from elsewhere in Europe and North America. It provides a comprehensive summary of existing knowledge and offers four future scenarios for beavers in Scotland for Ministers to consider. It covers a wide range of topics from beaver ecology and genetics, to beaver interactions with farming, forestry, and fisheries. The reintroduction of a species, absent for many centuries, is a very significant decision for any Government to take. To support the decision- making process we have produced this comprehensive report providing one of the most thorough assessments ever done for a species reintroduction proposal. Ian Ross Chair Scottish Natural Heritage June 2015 Commission from Scottish Ministers to SNH, January 2014 Advice on the future of beavers in Scotland SNH should deliver a report to Scottish Ministers by the end of May 2015 summarising our current knowledge about beavers and setting out a series of scenarios for the future of beavers in Scotland. The report should present a summary of existing knowledge about the likely impact of beavers living in the wild in Scotland. This summary would draw on the information gathered in Scotland from the Scottish Beaver Trial in Knapdale, the Tayside Beaver Study Group, the Beaver-Salmonid Working Group, and other projects and academic papers, as well as experience from elsewhere in the world. The scenarios in the report should be developed in an open and inclusive way with a range of interested stakeholders from the National Species Reintroduction Forum and other beaver-focused groups. They should set out the risks and benefits of each approach, and any management approaches to help mitigate the risk and/or maximise any benefits. The report should show clear links between the evidence base and the risks and benefits in the scenarios. The report should seek to describe possible ways forward to inform Ministers’ considerations of the issues rather than make specific recommendations. The report should be published. 2 Contents Section Page Foreword 2 Summary 4 Chapter 1 Introduction and background 8 Chapter 2 Sources of information 12 Chapter 3 Beavers and their interactions with the natural environment 18 3.1 Beaver ecology 19 3.2 Potential beaver habitat and population 26 3.3 Beaver genetics 34 3.4 Interactions with habitats and species 38 3.4.1 Woodland 38 3.4.2 Freshwater – Standing waters 46 3.4.3 Freshwater – Running waters 58 3.4.4 Bryophytes, fungi and lichens 64 3.4.5 Terrestrial vascular plants 72 3.4.6 Invertebrates 76 3.4.7 Fish 82 3.4.8 Amphibians and reptiles 92 3.4.9 Birds 96 3.4.10 Mammals 100 3.5 Summary 106 Chapter 4 Beavers and their interactions with the human environment 108 4.1 Socio-economics 109 4.2 Fisheries 122 4.3 Forestry 132 4.4 Agriculture 134 4.5 Infrastructure and general land use 138 4.6 Public and animal health 142 4.7 Summary 148 Chapter 5 Legal issues and the management of beavers and their impacts 150 Chapter 6 Future scenarios for beavers in Scotland 164 References 178 Appendix 1 Assessment of the Scottish Beaver Trial 190 Appendix 2 Summary of relevant legislation 196 Glossary 200 List of acronyms 202 Acknowledgements 204 3 Summary 4 Background or their remaining habitat may be improved, resulting in neutral effects or overall benefits at the catchment/ – This report been requested by the Scottish wider scale Government, and is designed to support the Minister – Some species and habitats of high conservation for Environment, Climate Change and Land Reform in importance have the potential to be adversely affected making a decision on the future of beavers in Scotland by beavers. This is especially the case where they are – The report provides assessments of the interactions isolated and in close proximity to riparian areas, and beavers may have on the natural and human where ecological continuity could be affected. There environments, examines legal and beaver management may be localised losses of riparian stands of aspen issues, and presents a number of future scenarios for and Atlantic hazel, and their associated species. beavers in Scotland The regeneration of other tree species felled by – The issues surrounding beaver reintroduction to beavers may also be hindered where deer are Scotland have been the subject of intense investigation abundant. There may be potential benefits of beaver and discussion over the last 20 years. This report presence for migratory salmonids, but there may also draws on work and experience generated through be possible adverse impacts, especially on the spring SNH-commissioned projects, the Scottish Beaver Trial, stock component of Atlantic salmon the Tayside Beaver Study Group, the Beaver-Salmonid – There is now a greater understanding of the Working Group, the National Species Reintroduction genetic backgrounds of beavers across Europe Forum and a range of other studies from Scotland and and in Scotland, including risks to genetic health abroad that may arise from inbreeding, which will assist in – Assessing the need for beaver reintroduction has a the development of any future reintroduction and legal basis, in particular the ‘Habitats Directive’. This reinforcement planning requires EU Member States to study the desirability of – Habitat mapping and population modelling tools have reintroducing certain species, such as Eurasian beaver. been developed that will assist in any future monitoring The potential for beaver reintroduction to contribute and management planning to the aims of the ‘2020 Challenge for Scotland’s Biodiversity’ is a further consideration Beavers and the human environment – At the current time there are two wild populations of beavers present in Scotland on a ‘trial’ basis, at – Beavers can provide a range of ecosystem Knapdale in Argyll and in Tayside. Any decision would services. These include ‘provisioning ecosystem need to consider their future, as well as the desirability services’ such as increased ground water storage, or not of any further reintroductions ‘regulation and maintenance ecosystem services’ such as flow stabilisation and flood prevention, and Beavers and the natural environment ‘cultural ecosystem services’ that relate to people’s recreational, educational and spiritual interactions with – Beavers are widely considered to be ‘ecosystem the environment. They can act as agents of natural engineers’, which means they have a large impact on change and restoration. These all contribute to human habitats and species through the alterations they make wellbeing and have socio-economic impacts to the physical environment – Socio-economic assessments have been – Beaver activity is largely restricted to freshwater undertaken at Knapdale and Tayside, and a range and associated riparian habitats, in particular where of recent, and potential future, costs and benefits broadleaved woodland is present. Substantial areas have been identified of these habitats occur across much of Scotland, and – Public consultation and surveys carried out over the these would be able to support a viable population of last 17 years have demonstrated overall public support beavers. Other habitats in Scotland would generally be for beaver reintroduction, although concerns have been unaffected by the presence of beavers more evident amongst some land use sectors – Experience from Scotland and abroad has – Beaver activities that may affect land use, such as demonstrated that, overall, beavers have a very positive agriculture and forestry, include burrowing and canal influence on biodiversity. Their ability to modify the construction, damming of smaller water courses, environment means that beavers not only create blocking of culverts, direct foraging of crops, and new habitats but also increase habitat diversity at felling of trees of commercial value. The extent and the catchment scale. Their impacts are dynamic and significance of the resultant impacts will depend on change across space and time local conditions. Concerns will tend to be greatest – The mechanisms by which beavers change in areas where beaver activities affect intensive environments and affect biodiversity include creating agriculture. However, beavers may also contribute ponds and wetlands, altering sediment transport positively to land use objectives relating to the processes, importing woody debris into aquatic improvement of the health and wellbeing of people, environments, creating important habitat features and aspirations for a high-quality, robust and adaptable such as standing dead wood, creating coppiced environment stands and unique vegetation structures, and