The Curlew. The evocative call of the curlew is inseparably associated with the beauty and serenity of British estuaries in winter. MarkCarwardine and wader specialist Peter Ferns from the University of Cardiff watch them feeding on the Severn Estuary. Plus what has been discovered by the British Trust for Ornithology about this enchanting migratory bird. Producer Sandra Sykes. Repeated tomorrow 11am