Development of a long-life bait for control of stoats

Abstract

Three types of long-life stoat bait (polymer, paste, and gel) were formulated from natural and synthetic bait ingredients after extensive testing of potential ingredients. Feeding trials demonstrated that baits containing natural extracts from rabbit and chicken were preferred to bait that contained only processed meals and synthetic flavours. The addition of preservatives and waterproofing agents to improve bait longevity, lowered palatability markedly in all bait types. The texture of bait also affected the amount of bait eaten, with most stoats rejecting baits that were hard or needed to be chewed before they could be swallowed. In this study, significantly more long-life polymer and paste bait was eaten than gel bait. The polymer bait remained palatable after one month in the field. Although all long-life bait formulations tested were less palatable than fresh meat, most stoats (i.e. ≥90%) consumed sufficient quantities of polymer and paste baits to receive a lethal dose (>5 g) if baits had contained a toxin. This was similar to the percentage of stoats eating pricked eggs, and better than consumption of non-pricked hen eggs. Methods for further increasing bait consumption and extending their effectiveness over time are being assessed, the ultimate goal being a long-life bait that is as palatable as fresh meat.