LAUSR

Abstract Context. Successful eradications of invasive rats from islands are paying tremendous conservation dividends, but failed eradications are economically and environmentally costly. For an eradication using rodenticides, every rat in every habitat must have sufficient exposure to toxic bait to receive a lethal dose. A post-operational review of a failed rat eradication on Wake Atoll, central Pacific Ocean, suggested that inadequate treatment of an intertidal habitat within the lagoon might have caused or contributed to the failure to kill all Polynesian rats (Rattus exulans), which have since recovered in number. This habitat could not be treated by aerial broadcast due to concerns about loss of bait to tidal action and perceived contamination of the marine environment. Aims. In preparation for a second attempt, we developed two alternative bait application strategies to distribute enough bait for a long enough period of time to successfully target rats, while minimising bait entering the ocean. Methods. We used camera traps and experimental bait provisioning methods to document rat foraging in the target habitat and uptake of bait. We developed two baiting strategy alternatives, and employed one of these strategies in a placebo bait application to demonstrate bait uptake by rats foraging within this tidally inundated habitat. Key results. Our results show active foraging by rats in the target habitat. Provisioning of placebo bait by various means preventing bait spillage into the marine environment was followed by heavy feeding by rats and minimal bait interference by crabs. Conclusions. We consider it likely that such a bait application strategy will be considered as an alternative during a future eradication attempt on Wake Atoll. Implications. The techniques we explore here will be useful for rodent suppression in other wetland areas requiring rodent control while protecting sensitive aquatic resources.