9 March 2015 Last updated at 16:37
Wild beavers found living on the River Otter in Devon are a species which was once native to the UK, tests have confirmed.
A breeding family was first spotted last year, although it is not known how they came to be there.
DNA results have shown the beavers are Eurasian rather than North American.
Devon Wildlife Trust said the confirmation moved them a step closer to releasing the animals, currently being kept in an artificial lodge.
Natural England has given the green light to a five-year trial to monitor and manage the impact of beavers on the river.
Earlier in March, the Department for Environment, Food and Rural Affairs (Defra) confirmed the beavers were free of tapeworm.


