Eradication of invasive rodents on islands of the United States

Many invasive rodents have become established in the United States and its territories. The species include several species of Rattus, house mice (Mus musculus), Gambian giant pouched rats (Cricetomys gambianus), ground squirrels (Spermophilus parryii), nutria (Myocastor coypus) and marmots (Marmota caligata). These rodents have caused serious impacts to native flora and fauna, agriculture, and other resources. Since the early 1990s, agencies have been eradicating rodents from various islands, primarily for conservation purposes. Of about 40 eradication attempts, 22 (55%) appear to have succeeded. For several islands, however, it is too early to determine if the attempted eradication has been successful or not. In the case of failed eradications, rapid re-invasion by rodents from nearby islands may be the reason. Numerous additional eradications are planned. We review the eradications, both successful and unsuccessful, that have occurred in the United States. Most eradications involved the use of the anticoagulant rodenticides diphacinone and brodifacoum. Rodenticides have been applied by hand-broadcast, bait station deployment, and aerial broadcast. We briefly review the strategies and methods used in eradication projects and the efforts to mitigate potential non-target and environmental impacts