Feral, Invasive Entanglements in the Galapagos Islands: Rats

The Galapagos Islands are known for their richness in biological diversity. As the ocean islands, being remote from a continent, they have maintained a unique ecosystem made up of numerous endemic species and were designated as a World Natural Heritage site by UNESCO, who had appreciated their ecological value.

The Galapagos Islands were remote and uncrowded islands in the past. However, people started to visit the islands from the 16th century; pirates, whaling ships and seal-catching boats often went in and out of the islands. In the 1800s, the Galapagos Islands were used as a place of exile as the Ecuadorian government had pushed ahead with the incorporation of the islands.

The Galapagos Islands, which once remained as researchers’ interest only, began to draw public attention and became a real tourist spot with the help of the success in stories of exploring the Galapagos Islands told in the 1920s and the designation as a national park in 1959. Fancy yachts, cruise ships, passenger planes and vessels with not only tourists but also inhabitants kept coming in and out of the islands, which finally brought many invasive species to the Galapagos Islands unknowingly or intentionally.

Rats are one of the invasive species within the Galapagos Islands. They caused damage to the islands’ ecology by preying on eggs and young of birds, reptiles and tortoises living there. Galapagos Doves and Galapagos Storm Petrels who nest on the ground were especially highly vulnerable to the rats. Galapagos Tortoises in Pinzón Island, an island in the Galapagos Islands, couldn’t reproduce for even more than a century because of those rats.

Even though three of the seven species of rice rats indigenous to the Galapagos Islands naturally became extinct due to the feral cats, their impact on the islands’ ecology was still so large that people declared war on invasive species including rats.

That Project Isabela – started in 1997 in order to get rid of #goats and pigs in the islands by Galapagos National Park and Charles Darwin Foundation – had successfully ended led to another project named Project Pinzón. It was a project that started from small islands like North Seymour Island and Rábida Island and aimed to finally eradicate house rats in Pinzón Island. The rats in North Seymour Island and Rábida Island were killed off in 2007 and 2011 respectively. In 2012, many helicopters were mobilized to spray an enormous amount of rat poison over Pinzón Island. However, some people were concerned about biological magnification, especially the poisoning of Galapagos Hawks that prey on rats, as one of the possible following results of spraying. Therefore, they captured all hawks in advance of spraying and released them six weeks later after the distribution of poison. But unfortunately, 16 of 60 hawks were dead as an unexpected consequence of the struggle with rats.