It's not exactly clear when the last wild saddleback giant tortoises (Chelonoidis ephippium) hatchlings escaped predation from the invasive black rat (Rattus rattus), but it is estimated that none survived in the entire 19th century. After introduction in the 17th and 18th centuries, and spreading through the island chain through human movement in the subsequent years, the rats were ravaging the islands' for eggs and tortoises were slowly dying out. A breeding program was established in 1965 to rear the tortoises until they were large enough to be unthreatened by rats but no successful breeding was occurring in the wild. Programs to control and eradicate invasive rats on several of the smaller islands have been attempted in the past, with some measure of success. In 2012, a project was initiated to eradicate the rats on Pizón island which is home to the tortoises.
A survey conducted in December 2014 has found ten wild hatchlings of the giant tortoises, the first in over 100 years and a solid indicator that the rat eradication program employed on the island has been effective. Further vigilance will be required to keep the rats from re-invading via swimming from nearby infested islands and through human movement.
To read about the hatchling discovery via Nature and the Galapagos Island Blog
To read about the 2012 Pizon rat eradication project via Nature and the Galapagos Island Blog