Beavers

Eurasian beaver (Castor fiber) are being reintroduced in many rivers across the UK. There are well established wild populations in Scotland and on the River Otter in Devon, with smaller numbers on the River Tamar (Cornwall/​Devon) and the Welsh River Wye (as of 2020). There are also enclosed populations of beavers. Some beaver populations are included on this map.

Beavers were native to the UK but became extinct in the 16th Century due to hunting for their fur, meat and castoreum’, a substance that beavers secrete from beneath their tails to mark their territories and is used in the perfume industry, reflected in the scientific name for the Eurasian beaver, Castor fiber

Eurasian beavers and American beavers are different species, but they are very similar in appearance and habits. 

Beavers are being reintroduced because they are a keystone species i.e. they have a disproportionately large effect on the ecosystems they inhabit. They are often called ecosystem engineers’ because of the way that they change habitat – they fell trees, dam rivers, tunnel into banks on such a scale as to change the nature of the habitat and the way that water flows; for example, their dams create wetlands and can prompt rivers to form new channels. 

Beaver female with kits 1 M Iike Symes comp
Beaver female with kits. Image: Mike Symes

As with all (re)introductions of species, the case of the beaver is generating much heat in the UK media from many angles: conservation, fisheries, climate change and natural flood management, to name but a few.

Beavers and Trout

The majority of questions we at WTT get asked regarding beavers involve passage issues for wild trout around dams i.e. can adult trout get past dams when migrating upstream to spawn or can juvenile trout get past dams to move downstream. While any ecological interaction between two species is inherently complex and influenced by locality and flow régime for example (in this particular case), we should remember that beaver and trout have co-evolved for millennia and coexist in many locations throughout Europe. However, the landscape throughout much of the UK where they might formerly have coexisted, prior to the extirpation of beaver, has changed considerably and is now subject to a suite of environmental pressures from humans that could influence the outcomes of any current interaction. 

Professor Jonathan Grey of the WTT and Lancaster University has reviewed the scientific literature and numerous reports from other organisations. Click on the links below to read the summary paper or full paper:

Wild Trout Trust beaver-trout interactions: summary

Wild Trout Trust beaver-trout interactions: full report

Note – neither report considers management options in any detail. 

Beaver dam
A beaver dam on a heavily modified side stream of the River Otter. Under the flow conditions in the photo, this dam would not be passable to most trout. Photo: Mike Blackmore

River Otter Beaver Trial, Devon

A population of beavers of unknown origin has been present on the River Otter in Devon since around 2008. They were known to be breeding in 2014. DEFRA originally planned to remove them but following a successful campaign it was agreed that the beavers would be the subject of a five-year trial to monitor their effects on the landscape.

Former WTT Conservation Officer for the South West region, Mike Blackmore, sat on the Fisheries Forum for the Devon Wildlife Trust River Otter Beaver Trial. The role of that forum was to ensure that fish and fisheries stakeholders (e.g. angling clubs) were engaged throughout the study and have the opportunity to ask questions and raise any concerns. Mike wrote a very interesting article on the River Otter Beaver Trial for our annual journal, Salmo Trutta in 2019. A PDF of the article is available here.

The River Otter Beaver Trial concluded in August 2020 and Defra decided to allow the beavers to remain. The final report of the trial is available here. The Management Strategy Framework published as a result of the study on the River Otter is available here.

Beavers in Scotland

Beavers were released into Knapdale Forest in Argyle in 2009 and monitored as a 5 year trial . A wild population also established on Tayside. 
Based on the experience of those two locations and other studies, this report on beavers was given to the Scottish Government in 2015. 
The Beaver Salmonid Working Group report, which provided input to the report to the Scottish Government is available here.

Beavers on Tayside are the subject of controversy as their population has now grown and areas of farmland are being adversely affected. Consequently, some beavers have been captured and relocated, or shot under licence to control their numbers.

In Scotland, beavers are (as of May 2019) a protected species
Scottish Natural Heritage have created a beaver mitigation scheme. 

in some places and situations the activities of beavers can have negative impacts on other interests such as farms, gardens, or other land. Sometimes this can be easily managed to prevent damage such as by fencing vulnerable areas or protecting individual trees and in others there is the potential for more novel techniques.’

Scottish Natural Heritage

Lessons learned from Bavaria

Beavers were reintroduced 50 years ago to a farmed and populated area of Bavaria and their experience has been shared via study tours from the UK. 

In 2012, a study group from Scotland visited Bavaria to develop a fuller understanding of how beavers were managed and what lessons could then be implemented in Scotland. The Bavarian situation is regarded by many people as being similar to Scotland, with the system of beaver management being something that they might wish to copy. The reports from the participants are available here.

This video (below) from the Cornwall Wildlife Trust is interesting and describes another study tour to Bavaria. However, there is limited mention of fish and no mention of salmonids.

Further information

The Beaver Trust is a charity established in 2019 and their vision is to recover Britain’s waterways and landscapes through the normalisation of beavers and the rapid and widespread re-establishment of beaver wetlands across whole river catchments.’ 

The Eurasian Beaver Handbook: Ecology and Management of Castor fiber , published in 2016, contains a comprehensive overview of management issues by one of Europe’s leading experts, Róisín Campbell-Parker. 

A good (short) introduction to beaver ecology is the Eurasian Beaver Handbook. This is book is also available from Amazon as a kindle / e‑book. By Róisín Campbell-Parker et al.

Josh Harris comp
Nina Constable Media comp
David Parkyn comp

Images courtesy of the Beaver Trust and (left to right) Josh Harris, Nina Constable Media and David Parkyn