Effects of coordinated poison-baiting programs on survival and abundance in two red fox populations

Abstract

Context Poison-baiting programs coordinated among neighbouring landholders should provide the most effective and efficient tool for controlling fox (Vulpes vulpes) populations and impacts in mixed agricultural landscapes, but the effects of such programs on fox mortality and abundance have not been well described. Aims This study aimed to describe the effects of coordinated fox-control programs conducted by landholders on fox mortality and abundance, and to evaluate the likely impacts of reduced landholder participation rates on the proportion of the fox population exposed to baits. Methods The effects of two baiting programs on fox abundance were evaluated using camera-trap surveys and abundance-induced heterogeneity models. The proportion of foxes surviving baiting was estimated by tracking the fate of 19 GPS-collared individuals. The benefits of coordinated baiting were examined using simulated scenarios based on local fox movements and bait distribution patterns. Key results Examination of actual and simulated fox home ranges demonstrated that coordinated baiting increases exposure of the target population to baits. However, 69% of foxes captured on properties that later baited were estimated to have survived the baiting period. Camera-trap surveys across baited and unbaited properties showed no detectable decline in average fox abundance after baiting. Conclusions Coordinated baiting increases the proportion of the fox population encountering baited properties. However, high fox survival and the absence of detectable declines in abundance after baiting showed that even well coordinated baiting programs can produce suboptimal results if many of the foxes using baited properties fail to locate and ingest lethal baits. Implications Baiting programs aiming to reduce the density and impacts of foxes in agricultural landscapes should strive to maximise participation among neighbours. Programs may also benefit from taking steps to improve bait-encounter and consumption rates within properties, for example, by deploying baits at sufficient intensity to provide all foxes with access to at least one bait within their short-term home range. Future research should aim to identify optimal baiting intensities within properties and conditions to maximise bait uptake.