Up until June 2012, Lonesome George was one of the rarest animals on earth. While Galapagos Tortoises are plentiful, George was the last of his species from Pinta Island.
For decades he was held in captivity, and safety, on Santa Cruz Island in the Galapagos, with hopes that a suitable mate would be found one day. During his time there at the Charles Darwin Research Station, he mated with a number of females from other Galapagos Tortoise species, but the eggs never hatched. Despite rewards being offered and numerous searches conducted, no female of his species was ever found and Lonesome George passed away from old age on June 24th, 2012.
The root cause of his species decline was the introduction of feral goats on his island. Despite eradication efforts, feral goats remain an issue on some islands of the Galapagos where they compete for food with native species such as tortoises.