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Rabida Island is the largest island that will be treated in this phase of the project.
The Galapagos National Park Service (GNPS), with the support of Island Conservation, the Charles Darwin Foundation, the Raptor Center of the University of Minnesota, Durrell Wildlife Conservation Trust, and Bell Laboratories, has initiated a project to restore altered ecosystems of several Galapagos islands through the elimination of introduced rodents.
Phase I of this ambitious plan, the first of its kind in South America, seeks to eradicate all introduced rodents on several of the small and medium-sized islands of Galapagos. In 2008, a pilot project eliminated rodents from the small island of North Seymour (455 ac). At that time, the bait was dispersed by hand.
During the current phase of the project, the GNPS seeks to eradicate rodents from the islands of Rábida, Bartolomé, Sombrero Chino, North Plaza, the two Beagle islets, and three of the Bainbridge Rocks.
Using a helicopter equipped with a high precision GPS , the pilot disperses bait over the surface of the islands in a pattern which will ensure complete coverage of the surface area. GPS data is downloaded to a computer to verify that flights comply with planned routes. This method of eradication has proven 100% effective on other oceanic islands.
Two applications will be made on each island and islet at a seven-day interval to ensure that 100% of the rodents consume the bait. On the islands included in Phase 1, the impact of other invasive species is near zero. Once introduced anis, a few invertebrates, and a limited number of introduced plants are eliminated, the ecological restoration of these sites will be nearly complete.
Before applying the product, scientists performed a rigorous risk analysis on non-target species such as hawks, finches, and mockingbirds, to determine possible effects of the poison on those species. The study determined that the Galapagos hawk (Buteo galapagoensis) was the species at greatest risk, since hawks could capture and feed on rodents that have consumed the bait. As a result, twenty individuals were captured from the two islands on which they were present. These birds will be kept in captivity for about two months, until the baits and affected rodents no longer pose a risk. The hawk cages were designed to minimize stress. Feeding is being conducted in a way that will not create dependency. This brief period of captivity will not impact the birds’ natural behavior.
This project has been aided by international experts with extensive experience with these methodologies. The rodent eradication phase of the project has included intensive training of park rangers in the overall methodology, bait dispersal, impact mitigation, management of non-target species, post-eradication monitoring, and project implementation and management.
• There are three types of introduced rodent in Galapagos: black rats, Norway rats, and house mice.
• Rodents have adversely affected reproduction of tortoises, iguanas, and land and sea birds (especially the Galapagos petrel, which nests in the higher humid zones of the larger islands).
• Previous rodent control efforts by the GNPS over the past four decades have reduced impacts of introduced rodents in targeted zones but never achieved complete elimination of those impacts. In addition control efforts must be on-going to be effective and are ultimately less cost effective than eradication.