The Galápagos tortoise or Galápagos giant tortoise (Geochelone nigra) is the largest living tortoise, native to seven islands of the Galápagos archipelago. They are long-lived, with a life expectancy in the wild estimated to be 100–150 years. Populations have fallen dramatically due to hunting and the introduction of predators and grazers by humans since the seventeenth century. Now only ten subspecies of the original twelve exist in the wild. However, conservation efforts since the establishment of the Galápagos National Park and the Charles Darwin Foundation have met with success, and hundreds of captive-bred juveniles have been released back onto their home islands. They have become emblematic of the fauna of the Galápagos Islands.