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Once introduced to an island, non-native rodents can cause considerable damage to the native flora and fauna, including the endangerment of endemic species (Campbell 1989; Witmer et al. 1998). As a result, there have been numerous efforts in recent years to eradicate introduced rats (Rattus spp.) and house mice (Mus musculus) from islands around the world (e.g., Buckle and Fenn 1992; Howald et al. 1999; Billing and Harden 2000; Key and Hudson 2000). Problems caused by introduced roof rats (Rattus rattus) at Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands, have been documented by the U.S. National Park Service (NPS) for many years (see Witmer et al. 1998). Of particular concern have been the impacts on endangered and threatened species, such as the hawksbill turtle (Eretmochelys imbricata), the ground-nesting least tern (Sterna antillarum), and the brown pelican (Pelecanus occidentalis). Efforts to protect and restore native vegetation, such as the lignum vitae (Guaiacum officinale), were hampered by rat foraging. Additionally, the NPS and the U.S. Fish and Wildlife Service (USFWS) have planned to reintroduce the endangered St. Croix ground lizard (Ameiva polops) to Buck Island as part of a recovery plan for that species (USFWS 1984). Rat predation poses a serious threat to lizards (Philobosin and Ruibel 1971; Meier et al. 1990) and A. polops reintroduction plans. The rats also posed a human health threat to visitors to Buck Island because since they harbor many diseases such as the tick-borne relapsing fever (caused by a Borrelia spirochete bacterium) that has been found to occur on Buck Island (Flanigan et al. 1991). Efforts to control the introduced rats on Buck Island have also increased public and territorial conservation agencies’ awareness to threats from exotic pest species.