Tim Birkhead is a professor of behaviour and evolution at the University of Sheffield. His research on promiscuity and sperm competition in birds helped to re-shape current understanding of bird mating systems. He was elected a Fellow of the Royal Society in 2004. As well as a passion for research, Tim is committed to undergraduate teaching and the public understanding of science. His talks (like The Early Birdwatchers) and popular science books have gained widespread recognition: The Wisdom of Birds (2008) won ‘bird book of the year award’ and Bird Sense (2012) was short-listed for the Royal Society Winton Prize. His most recent books are Ten Thousand Birds: Ornithology since Darwin (2014) and The Most Perfect Thing: Inside (and Outside) a Bird’s Egg (2016).