Phase II Galápagos Project: Baiting Pinzón and Plaza Sur Islands

Two years after conservationists successfully carried out an aerial bait drop to get rid of predatory rats on several small islands and islets in the Galápagos Archipelago, the team returned in late November, 2012, this time to eradicate invasive rodents from the uninhabited Pinzón and Plaza Sur Islands.

At 4,500 acres (1,815 ha), Pinzón is home to the Giant Pinzón Tortoise and the largest island in the archipelago to be treated in what is now Phase II of the Galápagos Restoration Project.

On December 8 & 9, operating from two park boats anchored off the shore of Pinzón -the Sierra Negra used as a helicopter platform and the Guadalupe River as the bait loading platform (photo above) - some 25 workers loaded pelleted bait (photo right), manufactured by Bell Laboratories, into the underslung hopper of a helicopter.

Over the two-day period, pilot Hamish Sheild, flying tight parallel lines across the island, dispersed a total of 45,635 lb. (20,700 kg) of bait to eradicate the island's rats.

Days earlier, on November 30, the team conducted a similar land-based operation to eradicate invasive house mice on the smaller Plaza Sur (30 acres/12 ha), aerially spreading some 490 lb. (223 kg) of bait.

Eradicating invasive house mice, Norway and black rats, which came to the islands centuries ago aboard the ships of whalers and explorers, is a top conservation priority for the Galápagos Islands.

Rodents are among the most serious threat to the rich biodiversity of this treasured ecosystem. Preying on the eggs and hatchlings of birds and reptiles, rats threaten fauna, as well as native flora, with extinction. Rats have prevented Pinzón Giant Tortoises from successfully reproducing in the wild for nearly 150 years.

Called the largest rat eradication in South America, this costly but necessary project, carried out 600 miles from Ecuador's coast, is supported by the Galápagos National Park, California-based Island Conservation, the Charles Darwin Foundation, Bell Laboratories, The Raptor Center of the University of Minnesota and private partners.

Prior to the Pinzón bait drop, conservationists gained valuable expertise and knowledge from the 2011 baiting on the smaller islands of Rábida, Bartolomé and ten islets. The Pinzón/Plaza Sur operation has moved them one step closer to their next mark of restoring Floreana Island. Ten times larger than Pinzón, Floreana supports nine globally threatened bird and reptile species and 32 globally threatened plants.

Two Years of Monitoring Ahead

Back on Pinzón, convinced from GPS data and maps that no areas on this rocky, volcanic island were left without bait, conservationists immediately shifted into long-term monitoring.

"Monitoring of rats and native species began before the applications and is continuing," noted Erin Hagen, project manager with Island Conservation. "There were some signs of rats succumbing after the first application."

Bait availability is also monitored. On some monitored plots on Pinzón, Hagen noted that bait disappeared in less than a week, while on others, pellets persisted for a month. Pinzón is covered in predominantly dry vegetation except at higher elevation, topping at 1,503 feet (458 m) where cloud cover increases humidity.
Pellets break down naturally when exposed to the elements. One significant rain can cause most of the pellets to dissolve very quickly.

It will be two years with no signs of rats before Pinzón and Plaza Sur can be declared "rat-free", yet past successes on Rábida, now confirmed to be rat-free, leave conservationists hopeful.

Gecko Discovered on Rábida

As an added bonus, on the last monitoring trip to the island, an Island Conservation team member found a gecko whose identification is currently being determined by Park staff. Geckos were only previously known from 5,700-year-old subfossils from Rábida.

Meanwhile, from Rábida, Island Conservation's Gregg Howald reports that, "doves have been nesting under rock ledges on the ground all over the place, mockingbirds and other birds appear to be in greater number than before, as do lava lizards - at least to me."