Optimising the palatability and longevity of stoat baits

Abstract

In New Zealand, introduced stoats (Mustela erminea) are significant predators of many native bird species. Trapping for stoat control is currently undertaken, but imposes logistical and cost constraints on the frequency and area over which their impacts can be mitigated. We sought to identify a highly acceptable stoat bait formulation with an extended field life that could be used for delivery of appropriate poisons. In feeding trials with wild-caught stoats, we screened 6 meat bases and > 20 humectant, preservative, binder or palatant compounds for acceptance and palatability. Significant differences in bait acceptance between female and male stoats were found. A humectant–preservative combination of polyethylene glycol (PEG 20,000) and sorbitol in rabbit mince was identified as optimal with over 80% acceptance by both male and female stoats and higher palatability (73.5%) than plain rabbit mince. This bait combination was acceptably ‘long-life’, with 80% of stoats eating PEG + sorbitol bait weathered for 28 days. This bait formulation thus has useful application in current stoat trapping programmes but also potential in future delivery of selective poisons, such as para-aminopropiophenone, to manage field populations of stoats.