Tim Birkhead is Emeritus Professor of Behaviour and Evolution at the University of Sheffield. His research on promiscuity and sperm competition in birds helped to re-shape our understanding of bird mating systems. Tim has been president of the International Society for Behavioural Ecology and the Association for the Study of Animal Behaviour. His study of guillemots – mainly on Skomer Island – for the past 49 years has helped to fuel his interest in the ultimate alcid, the Great Auk. As well as a passion for research, Tim is committed to the public understanding of science as has written several popular science books, including Promiscuity (2000), The Wisdom of Birds (2008), Bird Sense (2012) The Most Perfect Thing: the Inside (and Outside) of a Birds’ Egg (2016). His next book: Birds and Us will be published in 2022. He is married and has three fledged offspring and a dog, enjoys walking, playing the guitar and painting in his spare time.