Concern is growing about the risk of the H5N1 virus to wild birds

Reserves on the Dee Estuary and Conwy have some of the largest migratory bird populations in the UK.

Patrols for any sign of sick or dead birds have been stepped up to twice a week by RSPB wardens.

Concern has been growing about the spread of the virus in Europe, with confirmed cases in France and Germany.

"We are being extra vigilant and any dead birds will be reported immediately to the Defra helpline," said an RSPB Cymru spokeswoman.

Surveillance zones

The statement continued: "The RSPB is emphasising the importance of keeping wild and farmed or domestic birds apart and we support the surveillance zones around incidents announced by Defra last week.

"The risk to humans from a wild bird carrying H5N1 is low."

The Dee Estuary is listed as a European Special Protection Area for birds. According to the RSPB over 140,000 waders and waterfowl feed and roost in the estuary during the winter.

They include migratory species of ducks, swans and geese which spend several months in the area before returning to summer feeding grounds in other countries.

The Wrexham-based BASC is involved in monitoring for avian flu

The Wrexham-based British Association for Shooting and Conservation (Basc) has launched a special helpline to give advice on avian flu. It is running the service from its headquarters in Rossett.

The organisation, which has 123,500 members, is represented of three of the UK Government's expert advisory committees on the risk from the virus.

During the winter, the Basc has been closely involved in monitoring for any trace of the H5N1 virus in the wild bird population. Testing was carried out at 10 sites in the UK, including two in Wales.

A total of 1,500 birds were checked but no trace of H5N1 was found.

"We are consulting with Defra on a daily basis at the moment," said Basc spokesman Simon Clarke.

"Our members and our staff deal day-to-day with the shooting of game birds and agricultural pests - we know their ecology and have a wealth of knowledge," he added.

"It's obvious there has been a westward spread of H5N1 in recent weeks. We've always worked on the basis that it's a case of when and not if it arrives here - which is the only sensible way to work."

The H5N1 strain has killed dozens of people in Asia, the vast majority following close contact with infected birds.