written and produced by Graham Chedd ; directed by Larry Engel ; a co-production of Chedd-Angier-Lewis Productions and Thirteen in association with WNET.ORG
produced by Spectrum Field Productions LLC for Animal Planet ; executive producers, Guy Nickerson, Jim Rapsas ; director, Guy Nickerson ; producer, Sara Helman
written, produced and directed by Linda Garmon ; a Nova production by the WGBH/Boston Science Unit in association with BBC-TV, NDR International Hamburg and Nederlandse Omroepprogramma Stichting