 In 1965 , the first tortoise eggs collected from natural nests on Pinzón Island were brought to the Charles Darwin Research Station , where they would complete the period of incubation and then hatch , becoming the first young tortoises to be reared in captivity . The introduction of black rats onto Pinzón sometime in the latter half of the 19th century had resulted in the complete eradication of all young tortoises . Black rats had been eating both tortoise eggs and hatchlings , effectively destroying the future of the tortoise population . Only the longevity of giant tortoises allowed them to survive until conservation scientists and managers began to focus on Galapagos and the long path back to ecosystem restoration . 
