In 1967, the San Diego Zoo became part of "Operation Cheetah," an international effort to try to breed cheetahs in zoological parks outside of Africa. In 1963, the International Union for the Conservation of Nature (IUCN) had placed the cheetah on the endangered species list, largely because it was being hunted mercilessly by poachers for its spotted coat. Cheetah cubs Peter and Rita, both approximately four months old but unrelated, had been partially hand raised by Operation Cheetah organizer Don Hunt in Kenya and arrived at the San Diego Zoo on December 20, 1967. They added to another pair that had come to the Zoo in 1961, Dana and Sonya, two adults that had been in the Paramount Studios film "Hatari."