Twan Leenders is Senior Advisor for Science & Conservation at the Roger Tory Peterson Institute of Natural History in Jamestown, NY (www.rtpi.org). He previously was the conservation biologist for the Connecticut Audubon Society. Twan is a Curatorial Affiliate in Vertebrate Zoology at Yale University's Peabody Museum of Natural History. He is a professional herpetologist and enthusiastic wildlife photographer, with over twenty years of field experience in Central America. Twan authored the recent books 'Amphibians of Costa Rica - A Field Guide' and 'Reptiles of Costa Rica - A Field Guide', and he co-authored the 'The Wildlife Guide of Costa Rica: a Field Guide' - all for Cornell University Press.