Tim Birkhead is a professor at the University of Sheffield where he teaches animal behaviour and the history of science.

He is a Fellow of the Royal Society of London and his research has taken him all over the world in the quest to understand the lives of birds. He has written for The Independent, New Scientist, BBC Wildlife.

Among his other books are Promiscuity, Great Auk Islands, The Cambridge Encyclopaedia of Birds which won the McColvin medal and The Red Canary which won the Consul Cremer Prize.

He is married with three children and lives in Sheffield.

Catherine Rayner is an author and illustrator of children's picture books. She studied Illustration at Edinburgh College of Art where, for her final degree show, she created what would go on to be her debut picture book.

She is winner of the Kate Greenaway Medal and Booktrust's Best New Illustrator Award, and, in 2010, was the inaugural illustrator in residence at the Edinburgh International Book Festival.

As well as producing award-winning picture books, Catherine also exhibits her artwork in galleries all over the world and illustrates her own range of greeting cards.