Harmful predatory black rats must be removed to restore the island’s ecology
November 9th, 2012
The Galapagos National Park Service (GNP), Island Conservation, and other partners announced today that efforts to restore habitat for the native species of Pinzón and South Plaza Island, by removing invasive rodents, will begin the second week of November.
The ecological restoration of Pinzón and South Plaza is the second phase of an ambitious plan to eradicate rodents from small islands throughout the Archipelago. The first phase began in January 2011 with several small islets and smaller islands, including Rábida, Bartolomé, Sombrero Chino, North Plaza, the two Beagle islets and three Bainbridge Islets.
In this phase, the GNP, with support from Island Conservation, aims to eradicate rodents from Pinzón Island (1,800 acres) using the same techniques used in 2011. This eradication will be the largest to take place in South America.
A pesticide bait is distributed aerially by helicopter along the ground on the islands. Each island will receive two applications 7 days apart in order to ensuring that 100% of the rodents consume the product.
The helicopter is equipped with high precision GPS which allows the pilot complete control of the flight path in order to ensure complete coverage as work progresses. GPS information is downloaded to a computer on which the helicopter’s path of bait dispersal can be checked and then adjusted, if needed.
Baits and Risk Prevention
The rat bait tablets are composed of cereal laced with pesticide. The tablets have a limited time before they will disintegrate outdoors; with rain, they will not last more than 8 days or so.
Just as in 2011, scientists took great precautions to determine which endemic species on Pinzón and South Plaza might be at risk of ingesting the pesticide tablets. Risk analysis was performed for the Galapagos giant tortoise, Galapagos hawk, Galapagos dove, several species of finches, land snails, snakes, and the Pinzón lava lizard. It was determined that the species most at risk are the hawks, as they could capture and feed on rodents that have eaten the bait. Risk mitigation plans were established for the hawks, as well as the lava lizards and land snails.
The Galapagos hawk (Buteo galapagoensis) is endemic to the Galapagos Islands. Between November 12th and 14th, 30 hawks living on Pinzón Island were captured, and will be kept in captivity for about two months, which is the time needed to ensure that the remnants of bait no longer pose a risk. The cages used for captivity have been designed to minimize stress on the birds, and they are being fed in a way that will not create dependence upon their release. These successful techniques were developed on Rabida Island in 2011.
The current phase of the project also includes the training of park rangers in the following areas: bait application, impact mitigation, management of non-target species, monitoring, and implementation and administration of the project. Experts from around the world helped with this training prior to the first application of bait on November 11th.
• There are three types of invasive rodents in Galapagos: the black rat, Norway rat, and house mouse.
• Rodents have negative effects on the reproduction of tortoises, iguanas, land and sea birds, and especially on the Galapagos petrel, which nests in the wetlands of the larger islands.
• The GNP’s efforts to control rats over the past four decades have helped, but have not eliminated their negative impacts.
• The bait used is harmless to humans, but precautions have been taken by all personnel involved to wear the necessary protective equipment when handling the chemicals.