The landscape around a Norfolk chalk stream is being transformed in ways it has probably not seen for more than 500 years - thanks to a pair of beavers.
Norfolk Rivers Trust has introduced two of the semiaquatic, dam-building rodents into a headwater in north Norfolk - the culmination of an eight-year project.
Dr Jonathan Lewis-Phillips, lead ecologist, said: "We're really happy that they're out there and have started the work that we knew they would.
"They've already dammed the stream and created a nice little wetland next to it that they can live in.
"They've taken down some trees close to the river banks, and that allows light to come down onto the water, which allows the plants to grow, and helps to bring back insects and fish. We've seen all sorts of wildlife there already, including a kingfisher."
Dr Lewis-Phillips said the young adult beavers had come from the River Tay in Scotland as part of a programme where they are relocated if they become a threat to agriculture.
He said: "They should be enjoying the climate down here in Norfolk. They're a pair, and no doubt they will become a breeding pair once they settle in."
He said they were in a 7ha enclosure, and wanted to keep its exact location under wraps until they were settled in.
Dr Lewis-Phillips said: "Later on we will be able to show people where they are - we've got lots of plans to engage with the local community and get schoolchildren down there.
"It's the complex habitats they make that is so important to us as conservationists."
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.
Dr Lewis-Phillips said beavers were last widespread in Norfolk 500-600 years ago, but they were hunted to extinction for their fur and their scent glands, which were used to make perfume.
Beavers are considered a keystone species, which means they have a disproportionately large effect on their surrounding environment.
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