Born in 1954 in Paris, Guilhem Lesaffre lives in Brittany. He has been a teacher and pedagogical advisor for nearly forty years. Guilhem Lesaffre has practised ornithology in the field since 1971, in France, as well as in Europe, Africa, and North America. He participates in the regional and national census operations for nesting and hibernating avifauna. Through many publications and radio shows, he shares with the largest audience the secret of birds and tries to create awareness on the protection of birds and nature. 

From 2008 to 2015 he was chair of the Centre Ornithologique Île-de-France (CORIF), vice-president of the Agence régionale pour la nature et la biodiversité (Natureparif) between 2013 and 2017, and has worked as the administrator of the Ligue pour la Protection des Oiseaux (LPO) since 2016. He received the Legion of Honour in 2017 for his commitment to environmental protection.