The survey shows there are almost 250 Mandarin ducks in the Forest of Dean
The Forest of Dean has been recognised as one of the best places in the UK to see Mandarin ducks.
A survey has shown hundreds of the brightly coloured birds living and breeding in the area.
The recent count found there to be almost 250 Mandarins, mostly living around Cannop Ponds.
Former RSPB warden for the Forest, Ivan Proctor, who helped to carry out the survey, said the Forest of Dean is particularly important for the species.
"Mandarin ducks are not native to this country, they are native to the far East, but they have escaped into the wild here, and the Forest is actually the most important place in Britain for Mandarin ducks," he said.
'Twice as many'
Results of a count of the creatures in the Forest in November 2010 by Ivan and a colleague, found 245 mandarins "most of which were on the lower pond at Cannop".
"That's probably twice as many as you would find anywhere else in Britain," he said.
The first Mandarins came to the area in the late 1980s.
"When I first came to the Forest back in 1987 there were no Mandarins at all. It was around 1989/90, that the first ones appeared.
Ivan said it was around 1989/90 that the first Mandarins appeared
"The first I saw were a group of about half a dozen which came up out of the brook.
"We always used to think that they came from Slimbridge [Wildfowl and Wetlands Trust] but there is certainly someone over Longhope way who has bred Mandarins for a long time and it's quite possible that they came from there."
Mandarin ducks are a tree-nesting duck and perch high up in the surrounding oak trees, nesting in large holes and big nest boxes.
Ivan said, despite their abundance, they don't seem to be causing problems for native species:
"They are at least one introduction which doesn't seem to be doing any damage to anything else," he said.