Assessment of hazards to non-native mongooses (Herpestes auropunctatus) and feral cats (Felis catus) from the broadcast application of rodenticide bait in native Hawaiian forests

Primary non-target hazard assessment can be separated into two basic components: bait acceptance and toxicity. This bait acceptance study investigates the potential primary non-target hazard (direct consumption of bait pellets) that the broadcast application of rodenticide bait may pose to non-native feral cats and mongooses. The study was conducted in 4 different forest habitats in Hawaii using 2 different commercial formulations of placebo bait pellets. We documented vertebrates that came to placebo bait pellets at bait monitoring stations to assess bait acceptance. Bait pellets were monitored at each site using 40 infrared (IR) monitors/data loggers and weatherproof automatic cameras. During the 80 days of the study, cameras operated for 76,800 hours and recorded 21,211 slides of vertebrates at bait stations. Rodents, the target species, were the largest group, documented at stations in 98.98% (n = 20,994) of these photographs. Feral cats were detected in 0.09% (n = 20) and mongooses in 0.46% (n = 97) of the slides of vertebrates at bait pellets. The 117 photos of feral cats and mongooses represent 44 occasions where these predators encountered bait pellets; in 14 of these the bait was eaten. These data suggest that the primary hazard to non-native feral cats and mongooses from the broadcast application of pelletized rodenticides is very low. Thus, this study should support the effort to obtain regulatory approval for the broadcast application of rodenticide bait for conservation purposes in the state of Hawaii