 Between 1963 and 1974, all 14 adult tortoises discovered on the island were brought to the tortoise center on Santa Cruz and a tortoise breeding program was initiated.In 1977, a third Española male tortoise was returned to Galapagos from the San Diego Zoo and joined the breeding group.After 40 years' work reintroducing captive animals, a detailed study of the island's ecosystem has confirmed it has a stable, breeding population.