DOZENS of cygnets and scores of greylag geese have been killed by avian flu at a nature reserve near York.

The illness has struck the young swans and geese at the Lower Derwent Valley National Nature Reserve, a series of flood meadows, pastures and woodlands which support a rich diversity of plant species and outstanding populations of breeding and wintering birds.

A spokeswoman for the Yorkshire Wildlife Trust said that according to Natural England, who managed the reserve, about 80 per cent of this year’s cygnets - about 35 of the young swans - were lost in late September/early October.

She said this had left just the adults - which seemed to have been largely untouched - and one or two cygnets in some broods.

"Then, about two weeks ago we lost about 70 greylag geese across the site, out of the 2000 present, showing classic symptoms and some have been tested and proved positive," she said.

"Some have been on Wheldrake Ings and others on the adjacent Bank Island which were the only sites holding any water and birds at the time."

She said that with the recent floods, 'everything has become more spread out throughout the valley so hopefully that will help.'

She said a count last weekend had shown about 15,000 waterfowl and 10,000 gulls in the valley and no further dead or dying birds, although it was harder to survey for them now because of the floods.

"Advice from Natural England, which we support, is not to pick up dead birds but report them to Defra hotline," she said.

"They ask people to keep to visitor paths and locations – reducing additional stresses from recreational disturbance is really important and prevents unnecessary regular movements of birds around the valley."

A spokesperson for the Department for Environment, Food & Rural Affairs said the risk of of highly pathogenic avian influenza in wild birds in Great Britain was assessed as very high, but bird flu was primarily a disease of birds and the risk to the general public’s health was very low.

"The Animal and Plant Health Agency has been operating a year-round surveillance programme across Great Britain in found dead wild birds, which allows our world-leading researchers to better understand the latest strain and how it is spreading," they said.

"During the current outbreak, over 1,500 wild birds have returned positive results from over 360 locations and 61 different species."

Defra Biosecurity Minister Lord Benyon said wild birds were facing 'exceptional pressures' from avian flu this year.

"I very much share concerns about the impact avian influenza is likely to have on breeding populations of wild birds in the future, particularly those that nest in large numbers and represent some of our rarer and much loved species."