Chris HillThe harshest winter for decades has brought some odd behaviour from Norfolk's birds as they struggle to find food on the frozen ground.Chris Hill

The harshest winter for decades has brought some odd behaviour from Norfolk's birds as they struggle to find food on the frozen ground.

The RSPB has warned the savage weather is pushing Britain's wildlife to the brink of a crisis - and the effects have been noted at the society's reserves at Titchwell Marsh and Snettisham.

A young glaucous gull, more often seen feeding on seal carcasses left by polar bears in the Arctic, has been spotted after the cold conditions forced it further south than usual.

Normally-secretive woodcock and water rails have become uncharacteristically bold as their damp woodland feeding grounds freeze solid and they venture out into plain view to find a meal.

And a mystery disappearance of hundreds of over-wintering pink-footed geese prompted a theory that the birds could have begun their migration back to Iceland and Greenland early in favour of staying in frozen Norfolk.

The birds' population has since returned to normal levels, leaving RSPB staff wondering where they went - and how long they will continue to stay if food supplies remain scarce.

Dave Hawkins, visitor and publicity officer for the two reserves, said: 'The geese will have been suffering as the fields from which they get their food, like rotting sugar beet tops after the harvest, are frozen and covered in snow.

'What will be interesting though is to see if the birds stay longer in light of the cold weather.

'Woodcock and water rails are usually very difficult to see, but they are becoming increasingly easy to see as they get more desperate to find food. We have had up to six water rails around the visitor centre at Titchwell and woodcock have become very bold, even crossing some of the trails in broad daylight.'

Mr Hawkins said he had also seen strange behaviour from a snipe - which usually feeds by dipping its long straight bill into wet meadows or marshes.

'The other day, just feet from our office window, a snipe was on the ground watching chaffinches feeding on seed on our bird table,' he said. 'It flew up to join them and tried to feed in its accustomed manner, by trying to push its bill into the hard wood of the bird table. It knew there was food there but didn't know how to deal with it.'

The RSPB has launched an emergency plan to help wildlife through what could become 'the single greatest wildlife killer of the new millennium'.

The four-point plan includes:

Emergency feeding sessions for threatened birds including bitterns, which are vulnerable to extreme cold.

Urging the public not to disturb flocks of wetland birds, including ducks, geese, swans and waders, which forces them to expend energy unnecessarily.

Appealing to householders to feed garden birds, as the icy weather is forcing endangered species including redpolls, yellowhammers and tree sparrows into domestic gardens.

Asking farmers to put out supplementary food, especially in the form of grain tailings or residue from last year's crops, for threatened birds, such as corn buntings and yellowhammers.

Dr Mark Avery, the RSPB's conservation director, said: 'The extremely hard winter spanning 1962 and 1963 was arguably the single event that had the greatest impact on Britain's wildlife within living memory. With the icy weather predicted to last at least another week, this winter could be the single greatest wildlife killer of the new millennium.

'It is likely that the legacy of this hard winter will be seen in bird populations for many years to come.'

For further information on feeding garden birds visit www.rspb.org.uk.