Giant tortoises are endangered reptiles that were once found on 20 islands in the Indian Ocean. Now, only one species survives in the wild on Aldabra Atoll, and 11 subspecies remain in the Galapagos Islands. Giant tortoises can live over 100 years and once weighed up to 300 kg. They breed during the hot season but can mate year-round, and females migrate to nesting areas to lay 1-4 clutches of 2-25 eggs each season, which take 110-175 days to incubate. Overhunting drove many giant tortoise species to extinction by the 1800s.