Britain’s biggest birdwatch will take place this weekend, with thousands of families helping to record more than eight million birds.

Half a million people — including more than 15,000 from the West Midlands — took part in last year’s Big Garden Birdwatch when they recorded a total of 8.5 million birds.

The information helped experts understand how different species coped with the prolonged cold snap at the beginning of 2010.

The RSPB was also able to monitor birds visiting the UK and to assist species in decline.

Birdwatch takes place annually in the last week of January when nature-lovers are asked to record the number and types of birds in their gardens over an hour’s period.

This year the Arctic temperatures of December is likely to have an affect. Rare waxwings have already been seen in the Black Country, pushed south and west by freezing conditions in Scotland.

Most findings for the survey will come from volunteers watching their garden. But the RSPB has also this year joined forces with British Waterways in an attempt to get more data from rivers and canals.

RSPB spokesman Fen Gerry  said: “Carrying out the Birdwatch from a boat is a perfect setting. The waterways in the West Midlands are home to a wonderful diversity of birds.”

* To take part in Birdwatch note down the highest number of each bird species seen for one hour on  Saturday or Sunday. Submit results via www.rspb.org. uk/birdwatch or call 0300 456 8330 for a form to post.