Schoolchildren across the UK will be gazing out of the window with a purpose this week as the world's biggest school wildlife survey kicks off.

About 75,000 students and teachers in 2000 schools will be counting the birds that visit their school grounds for the RSPB's Big Schools' Birdwatch.

The survey, which has been running for more than a decade, will contribute to the results of the wildlife charity's Big Garden Birdwatch which is taking place next weekend.

The scheme helps to track bird numbers and involve youngsters in finding out more about the natural world on their doorstep.