Researchers want to find out how birds change from one year to the next, and how long they survive for. The team have been trapping and tagging birds at the Blair Drummond estate in Stirling, where the birds are fitted with a ring, weighed and measured, and their age and sex recorded. It is hoped that the same birds will be retrapped next year, when they will be examined again and the two sets of data compared.
So far, about 400 birds have been tagged. They include common species like blue tits, robins and blackbirds, but also summer migratory species.