In 2012, a helicopter could be seen zipping back and forth over Pinzón, one of the world famous Galapagos islands. Its mission: to cover the 18-km2 volcano with poisoned rat bait, thereby eradicating its population of invasive rodents for good.
Now, just two years later, the benefits of this initiative are starting to be seen. “We found 10 tiny, newly hatched saddleback tortoises on the island early last month,” report conservationists in correspondence to Nature this week.
Owing to rat predation, it’s thought that no tortoises have hatched out on Pinzón in 150 years or more. But baby giant tortoises are notoriously difficult to spot, often concealed beneath loose lumps of lava so there were probably very many more. “I suspect there were 100 to 300,” says James Gibbs, who has written a lovely piece for the Galapagos Conservancy blog about his recent survey of Pinzón.
By the end of our trip, the team had encountered over 300 tortoises, resulting in an overall population estimate well over 500, a near tripling of the population from the 100-200 very old individuals encountered on Pinzón when the Galapagos National Park was established in 1959. [James Gibbs, Galapagos Conservancy blog]
“They are breeding again in situ,” he says.
Gibbs and others on the survey looked very hard for signs of live rats, but found none. “As a biologist I have had a time comprehending that every rat was killed,” he says. “But they seem to have done it.”
The challenge now, in an archipelago with 30,000 residents and 200,000 visitors every year, will be to prevent rats from finding their way back to Pinzón.
For more details of the rat eradication initiative (codenamed Project Pinzón), take a look at this feature I wrote for Nature back in 2013. I also covered Project Pinzón in my book, The Galápagos: A Natural History (Profile, 2014).