Proceedings of the Vertebrate Pest Conference

The majority of bird species endemic to French Polynesia are facing the threat of extinction from introduced mammals, particularly rodents. Relict populations of some species persist on uninhabited atolls, offering an opportunity to protect these species on their breeding grounds. With limited prior knowledge of the eradication environment, a campaign to eradicate Rattus exulans from three islets within the atoll of Tahanea, Tuamotu Archipelago, was undertaken in July 2011 to create additional nesting habitat for the endangered Tuamotu sandpiper (Prosobonia cancellata) – the titi. The three islets of Toreauta (5.3 ha), Toreauta Iti (0.7 ha), and Kotuetue (1.1 ha) are all located within expected rat swimming-distance. Trapping, chewblocks, and nighttime surveys were used to establish a baseline estimate of rodent activity and to confirm the project’s success. The eradication involved two hand broadcast applications of rodenticide containing brodifacoum (25 ppm) on the islands of Toreauta and Kotuetue. Bait was broadcast at these sites at a density of 20 kg/ha during the first application and bait availability was monitored. Eight days later, and informed by the results of bait availability monitoring, an additional 10 kg/ha was broadcast. Baiting of the Cocos nucifera canopy was also completed. To ameliorate risk to resident titi on Toreauta Iti, makeshift bait stations were constructed of available materials and baited and maintained with 120 grams of bait for 14 days. Rodent activity in 2011 showed 22% of chewblocks with rodent sign and 17 rats observed during nighttime surveys. In 2012, one year after the eradication was implemented, rats were not detected with chewblocks or during nighttime surveys. Comprehensive application of bait to all potential rat habitats including the palm canopy and the inclusion of islets that could have provided a source of reinvasion contributed to the success of the campaign, while adaptively managing the baiting strategy lowered risks to non-target species.