Toxin-laced rat carcass baits for stoat elimination

Stoats are implicated in the severe decline of certain iconic endemic species in New Zealand. Stoats are notoriously difficult to control, as they are highly cryptic and often neophobic around control techniques such as traps and poison baits in tunnels. Stoats are often killed through secondary poisoning in both aerial and hand-lay operations targeting other mammalian pests. We prototype trialled a novel approach to poisoning of stoats: wild-caught ship rats that had consumed (and subsequently died from) a lethal dose of 1080 cereal baits in a captive facility. Stoats in the treatment area were targeted at food-lured (egg mayonnaise) camera trap sites that had multiple stoat visitations prior to baiting with toxic rat carcasses. Stoats were recorded taking toxic rat carcass baits from 7 out of 15 hand-laid sites. No other species were observed taking toxic rat carcasses during the study. The number of cameras in the treatment area that detected stoats was significantly reduced for 30 days after toxic baiting. There was no significant difference in number of cameras that detected stoats during this period in the non-treatment area. These results suggest that 94% of the stoats in the treatment area were poisoned using toxin-laced rat carcasses within one week of baiting. Toxic rat carcass baits placed at locations of known stoat activity may be a highly successful method of eliminating individual stoats at very low density.