Since the ringing programme began in 1909, there have been around half a million recoveries of birds ringed in the UK and the data yielded has enabled the BTO to build up a picture of the movements of around 200 migratory species. This volume details the ringing scheme, migration ecology and study methods and contains detailed texts for individual species, written by experts on their movement. It also critically examines the potential biases in the ringing-recovery information caused by ringing and finding circumstances.