The Española giant Galapagos tortoise, which can weight 250 kg (550 lbs) and live a century, was really in bad shape in the 1960s. The island of Española, which is part of the Galapagos (see map below), only had 15 individual - 12 females and 3 males - remaining at the species' lowest point, thanks in part to the introduction of feral goats introduced in the ecosystem over a hundred years ago. The goats out-competed the tortoises for the cacti that they prefer eating. But thanks to a 5-decade conservation effort, the species now seems to have made a 'miraculous' and, most importantly,stable recovery.
This is a nice contrast to the tragic fate of Lonesome George, who we wrote about in 2012. The world's last remaining Pinta Island tortoise, George died at age 100, sealing the fate of his species.
Google Maps/Screen capture
How was the Española population of giant tortoise saved? The Galapagos Islands National Park Service began a program of captive breeding and reintroduction in 1973. Using an enclosure on another island to help some of the remaining tortoise to focus on breeding, they were successful in reintroducing more than 1500 of the captivity-raised giant tortoise offspring on the island of Española.
For this effort to be successful, the non-native goats had to be culled, and eventually exterminated. Otherwise, the life-sustaining catci could never have recovered:
"[The goats] would feast on the roots... and chew away at the bark, and eventually that would topple these cacti. And then they had an incredible buffet of maybe 500-1000 years of cactus growth, demolished in a week or two," explained Professor Gibbs, from the College of Environmental Science and Forestry at the State University of New York.
According to Prof Gibbs, "more than half" the tortoises released since that time are still alive, and they are breeding well enough for the current population to move forward (if slowly -- we're talking about giant tortoises after all...), without further help from humans.