The mandarin duck is a native of Eastern Asia, mainly China and Japan. It became known in Europe in 1599 through a painting brought to Rome by Japanese envoys. Live birds were introduced to Britain shortly before 1745 when it was known as the "Chinese teal". Drawings of the birds in the garden of Sir Matthew Decker in Surrey were made by the naturalist George Edwards. Thereafter many wealthy landowners tried, often successfully, to establish the bird in their grounds and pockets of mandarins developed across the British Isles. I recently acquired the book, "The Naturalized Animals of the British Isles" (Christoper Lever, Hutchinson, 1977) where the above facts (and many more) can be found. Interestingly the large colony at Cannop Ponds in the Forest of Dean isn't mentioned: perhaps it is of more recent establishment. The photograph shows a striking male mandarin at the Ponds, standing on ice.
photo © T. Boughen Camera: Nikon P900
