River Otter Beaver Trial

This summer marked a landmark moment in conservation when, after years of uncertainty, the government announced that England’s first wild breeding population of beavers for 400 years had been given the permanent right to remain on the River Otter.

The decision signals the first legally sanctioned reintroduction of an extinct native mammal to England and means that up to 15 family groups of wild beavers on the River Otter in East Devon now have a secure future. Devon Wildlife Trust started running a beaver project on a securely-fenced, private site in West Devon in 2011 to monitor the ecological effects of these once-native mammals. Supported by Viridor Credits Environment Company, The Truell Charitable Foundation and Westland Countryside Stewards, research has focused on the impact of beavers on trees, plants, wildlife populations, water quality, water levels and flow rates through the site, proving that their dams have reduced the flow of tonnes of soil and nutrients from nearby agricultural fields into the local river system. Devon Wildlife Trust’s pioneering five-year River Otter Beaver Trial in East Devon commenced in 2015, coming to a conclusion earlier this year. Mark Elliott led the River Otter Beaver Trial from the beginning and he looks back at this remarkable story, saying: “There was a great deal riding on the government’s decision. Beavers are astonishing animals, capable of breathing life into our rivers and wetland habitats. They are known as a ‘keystone species’, because of the disproportionate impact they have on shaping their environment, and because of the benefits that this brings to a whole host of other wildlife. Beavers also benefit people. Their wetlands slow the flow of water off the land, reducing flooding and the impacts of droughts – things that will become increasingly important as we face an unfolding climate emergency.” 

The beavers’ story stretches back to 2008 when two animals were thought to have escaped or been released by persons unknown into East Devon’s River Otter. For several years they lived with relatively few people knowing of their existence. Things changed in 2013 when evidence emerged that the beavers were breeding. This was big news: the first breeding beaver population in England for 400 years was now living on a Westcountry river. The government responded, proposing to round up the beavers and remove them, but what followed was a fierce campaign from local communities for the beavers to remain. It was then that Devon Wildlife Trust stepped in to broker a compromise; it was agreed the beavers could stay under the conditions of a five-year licence. So, the River Otter Beaver Trial began in 2015, led by Devon Wildlife Trust, working with Clinton Devon Estates (a major local landowner) and our long-standing research partners, the University of Exeter. The trial was set the task of not only monitoring the beavers’ numbers, geographical spread and health, but also researching their impact on local wildlife, the river’s health, on farming and farmland, on people and the local economy. This was a big job, especially as the trial came with no funding. It has taken a lot of time, energy and dedication from staff, project partners and local volunteers, but five years on, the trial is complete and its findings make striking reading. The following conclusions are all taken from a detailed investigation led by University of Exeter academic, Professor Richard Brazier (see exeter.ac.uk/creww/research/beavertrial). 

Reduced flood risk

A sequence of beaver dams constructed upstream of an East Devon village with properties at risk of flooding has seen a reduction in peak flows in that stream. 

Beavers thrive 

Two family-groups in 2015 grew to as many as 13 territories by 2019, with beavers dispersing throughout the River Otter and some of its smaller tributaries. Detailed veterinary work concludes the beavers are healthy and present no significant risk to human, livestock or wildlife health.

Fish jumping dams

Videos and pictures of fish jumping a beaver dam also help demonstrate that migrating fish are able to navigate dams in certain flow conditions. The trial’s surveys showed the abundance of fish in beaver pools above dams was 37% higher than in other parts of the river without beaver dams.

Benefits to other wildlife

The activities of beavers, especially their dam-building have created new wetlands for local wildlife. Water voles, teal and frogs are just a few examples of species to have benefited from the beavers’ ability to open up scrubby areas of land and raise water levels.

Selective dam building

In October 2019 there were 28 dams in place throughout the River Otter’s

catchment and only six of the 13 beaver territories contained dams, generally only in the smaller headwater streams and ditches, and not in the main river where the water is already deep enough.

Beavers benefit fish

In the River Tale (a tributary of the River Otter) which has fast and strong flows, dams can often be partially destroyed during high rainfall. Their temporary nature has created new features in the river including meanders, shallow gravel beds and pools, which are starting to be used by young trout.

Local impacts on farming

During the trial, beaver dams caused issues with land-drainage at five sites. Devon Wildlife Trust intervened to reduce the impact, sometimes removing dams, and in one place installing a device (a so-called ‘beaver deceiver’) to reduce a dam’s water level.

Beavers like apples

There has been no recorded beaver impact on forestry plantations, but small riverside orchards have seen beavers feeding on both windfall apples and apple trees - tree-guards have prevented further damage.

Beavers are popular

2017 national public perception questionnaires found that 86% of 2,741 people surveyed supported beaver reintroduction. By 2019 a repeat survey of 386

people found 90% in support.

The trial shows that the costs of beaver reintroduction are outweighed by the benefit they bring. Beavers provide ecosystem services, including flood alleviation, helping to remove pollution from water supplies and improving or creating wildlife habitat, as well as social gains, most notably a boost in local eco-tourism. Funding will be needed to manage an expanding beaver population, to solve local issues where they arise and support communities with information and education, and particularly provide help for farmers and landowners to allow beavers to create new wetlands. News of other populations of beavers living wild has also emerged from West Devon, North Somerset, the River Wye and elsewhere, seemingly the result of escapes or unsanctioned releases. Our work to keep beavers in the wild will continue as we monitor their activities, ensuring they continue to live happily alongside the local community.

Devon Wildlife Trust

If you would like to support our work you can become a member for as little as £3 a month, or to make a donation please visit devonwildlifetrust.org/support-us/make-donation.