Beavers could be reintroduced into the wild under new proposals which have drawn praise from nature campaigners - but concerns from farmers.
The government has launched a 12-week consultation on proposals for a "cautious" return of the semi-aquatic mammals to English rivers.
Conservationists in East Anglia say the creatures are "eco-engineers" whose dam-building and tree-felling can restore wetland habitats, boost other wildlife, reduce flooding and support eco-tourism.
Beavers have already made a restricted return to west Norfolk, with two pairs successfully released under licence into an enclosure at Wild Ken Hill last year as part of a large-scale rewilding project.
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Last month the estate, between Heacham and Snettisham, witnessed the first young beaver to be born in Norfolk since the 16th century, when the species was hunted to extinction in Britain for its fur and meat.
The new proposals would mean licences for reintroductions into the wild would need to meet criteria including demonstrating positive stakeholder engagement and a comprehensive assessment of impacts on surrounding land, waterways, infrastructure, habitats and species.
Nature campaigners including The Wildlife Trusts, The Beaver Trust and Rewilding Britain welcomed the proposals, while farming leaders warned that beavers could have detrimental impacts on trees, riverbanks and land drainage if allowed to roam wild.
Kevin Hart, interim joint chief executive of the Norfolk Wildlife Trust, said: “Beaver populations could make a significant contribution to improving the quality of wetland habitats.
"Research has produced a comprehensive body of evidence showing how they can help to improve the quality of rivers, riverbanks and the wildlife they support as well as reducing flood risk.
"However, we know that any reintroduction of native wild species to areas where they have been missing for long periods need robust feasibility studies and long term monitoring to have the highest chance of success.”
Under the proposals, beavers are also set to be given legal protection, making it an offence to deliberately capture, kill, disturb or injure them.
The National Farmers' Union (NFU) warned that this could make it difficult to stop any negative impacts from the animals, such as damaging trees and impeding farmland drainage.
Rob Wise, NFU environment adviser for East Anglia, said: “It is positive that any reintroduction will be strictly licensed by Natural England and it is important any approved licensing includes a long-term management plan, developed with local farmers and backed with adequate funding.
“Any effects on a farmer’s ability to produce food needs to be included as part of a full impact assessment, carried out before any licence is issued.
“What is equally important is the government’s intention to give beavers legally protected status. Our major concern is the management and control of beavers once they are in the wild.
“Beaver reintroductions can have negative impacts, potentially undermining riverbanks, damaging trees, impeding farmland drainage and causing low-lying fields to flood.
“The successful reintroductions we have seen in Norfolk and Essex have been into enclosures. If in future these animals are released into the wild, we need to know they can be controlled if they cause harm.
“We therefore urge the government to bring forward its separate consultation on revising protected species legislation as soon as possible and to really listen to the practical concerns of farmers and landowners.”
Environment secretary George Eustice said Defra is committed to providing opportunities to reintroduce formerly native species, such as beavers, "where the benefits for the environment, people and the economy are clear".
He added: "But we also understand that there are implications for landowners, so we are taking a cautious approach to ensure that all potential impacts are carefully considered."
The new measures would only apply to England. Scotland has also seen the return of beavers into the wild, with the Scottish government giving them legal protection in 2019, although they can be killed under licence if they damage farmland.
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