The effect of device density on encounters by a mobile urban carnivore: Implications for managing peri-urban wild dogs

Abstract

A variety of devices are often placed in the landscape to count, catch, kill, or otherwise manage wild species. It is important to understand the interactions between such devices and the species of interest to achieve and improve the efficiency of research and management objectives. Canid pest ejectors (CPEs; hereafter ejectors) are a device recently made available for use in Australia for the control of wild dogs (Canis familiaris) and European foxes (Vulpes vulpes), but there is limited data to inform best practice deployment for their safe and effective use in peri-urban environments. Data from eleven GPS collared wild dogs in peri-urban north-eastern Australia were used to quantify and compare encounters with three different densities (spacings of every 200 m, 500 m or intersections only) of modelled ejector locations placed in each respective animal’s home-range. Survival analyses was conducted on each modelled ejector to determine the effect of the three road-based deployment spacings and the effect of sex and season on the initial encounter by wild dogs. Ejector survivability (i.e. encounter) was significantly different between seasons for individual wild dogs, and between male and females, with ejectors placed within female home-ranges found to have significantly less survivorship than those in male home-ranges. Ejectors spaced at closer intervals (200 m) had a greater percentage of days with wild dog encounters. Placing ejectors at intersections provided the highest probability of wild dog encounter, with the average ejector at this location 1.5 times more likely to be encountered than those at the alternative spacings (200 m and 500 m). Our results show that achieving the most appropriate ejector placement depends on whether maximum interactions or maximum efficiency is desired, which are important considerations in the short- or long-term deployment of ejectors for the management of wild dogs. These findings assist the development of guidelines for the optimal and efficient placement of ejectors to ensure their safe and effective use in peri-urban environments. They also have additional relevance for other applications of device placement to survey or manage mobile species in peri-urban areas.