Image credits
Image Credits:

Photos: How do you know when a species has become extinct?: Pacific seahorse: courtesy of Gerald and Buff Corsi, California Academy of Sciences; Illustrations: Introductory page: letters and their animations: Eric Hamilton; great auk: courtesy of AMNH Department of Library Services, #6266, extinct 1844. By Charles Hamilton Smith, from Charles Hamilton Smith, Original Drawings, 1795-1859. 23 vols; laughing owl: courtesy of AMNH Department of Library Services, #6253, extinct New Zealand, c. 1914. By John G. Keulemans, from G. D. Rowley, Ornithological miscellany, vol. 1. London: 1875.; O'ahu 'O'o: courtesy of AMNH Department of Library Services, #6286, By John G. Keulemans, from Lionel Walter Rothschild, The avifauna of Laysan and the neighbouring islands, London, 1893-1900; endangered ticker animals: Patricia J. Wynne