The chimpanzee population on Rubondo Island results from an introduction of 17 individuals in late 60ties and it is the only example of a viable, long-term self-sustaining released chimpanzee population with a minimum of human intervention at the time of release and afterwards. Project studied these chimpanzees as a model population adapted to a new environment from the aspects of feeding behavior, self-medication, and parasite exchange among released chimpanzees, indigenous vervet monkeys (Cercopithecus aethiops) and humans. Data on chimpanzee feeding behavior and self-medication were obtained by behavioral observations and analyses of feeding remains and feces. Fecal samples of chimpanzees, vervet monkeys and humans were systematically analyzed to identify and compare their parasite fauna. Obtained results contributed to our understanding of chimpanzee behavioral and ecological flexibility and helped to increase the success of next releases.