Garden favourites may be left out in the cold

But more unusual visitors, including redwings and tree sparrows, are likely to be spotted by householders taking part in the annual survey, as the cold weather forces them into gardens in search of scarce food.

The prolonged wintry conditions are bad news for small-bodied birds such as the robin, which could crash out of the survey's 10 most seen birds for the first time since the nationwide birdwatch began more than 30 years ago.

Robins, wrens and long-tailed tits are among those struggling to

survive in the recent frosty weather.

Long-tailed tits made it into the annual study's top 10 for the first time last year, but are unlikely to be there again this year.

The charity, which has been running the survey since 1979, said it was keen to see how the wintry weather would affect bird numbers in gardens, and whether people see unusual visitors forced towards homes in search of food.

The conservationists are also keen to see if there are any regional variations in numbers as birds fly to milder areas in search of shelter from the weather or more available food.

Dr Mark Avery, RSPB director of conservation, said: "We can expect to see some more unusual visitors to gardens, particularly redwings, fieldfares and tree sparrows that are struggling to find food elsewhere.

"It's unlikely the long-tailed tit, which famously flew into tenth

place in 2009, will remain in the top 10 this year.

"Sadly we may even see the nation's favourite garden bird, the robin, also fall out of the top 10 in 2010."

Around half a million people are expected to take part in the Big Garden Birdwatch this weekend. To find out more about participating in the birdwatch and to submit results online, go to