The first beavers to live wild in England for centuries are to be allowed to remain in their new home on the River Otter in east Devon after a five-year reintroduction trial. The government gave permission on Thursday for the reestablished colony to remain in the area, the first wild breeding of beavers in 400 years and the first legally sanctioned reintroduction of an extinct native mammal to England. Up to 15 family groups of beavers are now estimated to live on the Otter, after seven years in which their future success did not always look assured. Peter Burgess, director of conservation at Devon Wildlife Trust, which has overseen the reintroduction trial, told the Guardian: “There have been some sleepless nights, and it was very stressful in the early stages. We knew the benefits, but things were hanging on a knife edge over securing the licence at the beginning.” The beavers started out as interlopers, when a family group were found to be living on the River Otter in 2013, their origins unknown. They were threatened with removal, but the Devon Wildlife Trust and community groups stepped in and tried to show the beavers were European, rather than north American, and eventually gained a licence for a five-year trial, which was extended in February to conclude this month. Beavers alter the landscape and ecosystems in and around waterways, with their dam-building helping to reduce pollution and boosting local wildlife populations, including fish and amphibians, according to a study from Exeter University. As the UK’s climate changes under global heating, droughts and devastating floods are likely to become more common, and beavers can help with both: their damming slows the speed of floods downhill when there is too much rainfall, and helps provide water storage that stops rivers running dry during droughts. The dams also filter out pollutants and stop topsoil being washed away. Key to the success of the River Otter project was getting local people and farmers involved and explaining the benefits beavers can bring, as well as providing support when needed, said Burgess. There were several incidents of localised flooding of farmland, when the landowners were concerned, but by providing expert support the reintroduction team were able to resolve the problems. “If landowners know there’s someone they can pick up the phone to, it really helps,” Burgess said. “Animals are much more likely to be welcomed if that is the approach.” Beavers can grow to 20kg, but contrary to popular misconceptions, live on an exclusively vegetarian diet and do not eat fish. Richard Benwell, chief executive of the Wildlife and Countryside Link, said: “It’s great to see that the reintroduction of beavers in this trial has resulted in a win-win for the local area, boosting wildlife and tackling man-made problems. The trial clearly proves the benefits of nature-based solutions to dealing with flooding, water quality and resilience to climate change. “We hope to see more such welcome projects introduced by government as part of flooding, water and climate planning.” However, Phil Jarvis, chair of the environment forum at the National Farmers’ Union, warned that farmers would want to see an “exit strategy”, as well as adequate funding and a long-term management plan, before any expansion. “Beavers can have a significant local impact on the countryside and farming; from creating dams that can undermine riverbanks, to impeding farmland drainage with waterlogged fields becoming unsuitable for grazing and cropping; all lead to serious implications on our ability to produce food,” he said. “We must see a well-thought through exit strategy if any major issues occur.” The government said on Thursday it would consult later this year on the possibility of further reintroductions, and a national approach to the issue. An increasing number of farmers and conservationists are considering rewilding schemes for their land, and there are calls for reintroductions of animals from boar to lynx and wolves. A survey of members and supporters of the Game and Wildlife Conservation Trust on lynx reintroduction received 4,500 replies, of which 68% were in favour. No more releases in the wild will be allowed until the consultation is complete. Rebecca Pow, environment minister, said: “We are firmly committed to providing opportunities to reintroduce formerly native species, such as beavers, where the benefits for the environment, people and the economy are clear. “But we also understand that there are implications for landowners, and take care to ensure that all potential impacts are carefully considered.” • This article was amended on 6 August 2020 to clarify in the first paragraph that the beaver colony discussed is the first to live wild in England for hundreds of years, not the UK.