A curious creature gazes into a camera lens at Strumpshaw Fen.
Photographer David Brooker said he first thought the animal was a stoat as it was so large, but suspected it may be a weasel.
'I could not believe it when it ran past me twice,' he said. 'It was so fast that I missed loads of shots as I followed it up the path.'
He followed it several hundred yards to a river and back, finally capturing photos of it when it paused atop a log to look for prey.
Francis Farrow, who is Norfolk's county mammal recorder, studied the photographs and confirmed that the animal was, indeed, a weasel.
He said that identification was straightforward from the set of photographs taken by Mr Brooker, as the animal's tail was visible.
The weasel has a small tail with no obvious black tip, whereas the stoat has a long tail of 5cms to 13cms in length, which can be twice as long as a weasel's, of 3cms to 6cms, with a distinctive black tip.
Other differences, apart from overall body size – a stoat is 21cms to 31cms and a weasel is 17cms to 25cms, are more subtle.
Stoats tend to be sandy-brown in colour with cream underparts, whereas weasels are darker chestnut brown with whiter underparts.
The division between the upper and underparts is fairly straight in stoats and irregular and spotted in weasels. Such lines are, however, hard to distinguish with fast-moving animals so it is best to concentrate on size and the black-tipped tail.
Mr Farrow added: 'Once such features are well-known the animals are weaselly told apart, because they are stoatally different!'
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