Tim is an Emeritus Professor of Zoology in the School of Biosciences at the University of Sheffield, where he has studied promiscuity in birds, avian egg shape and maintained a long-term study of common guillemots on Skomer Island, Wales since 1972. His interest in the ecology and behaviour of guillemots fostered a passion for the great auk that includes a forthcoming book The Great Auk: its Extraordinary Life, Hideous Death and Mysterious Afterlife (13 March 2025 Bloomsbury).