Increasing the target specificity of the canid-pest ejector for red fox (Vulpes vulpes) control by using a collar to exclude larger canids

Abstract

Context Canid-pest ejectors (CPEs) offer a compromise between broadscale free-baiting programs that can have non-target impacts and more target-specific methods such as trapping and shooting, which are inefficient across larger scales. CPEs target wild canids, such as red foxes (Vulpes vulpes) and wild dogs (Canis spp.). However, there are situations where red fox control is required, but the risk to non-target canids, such as dingoes and other dogs, prevents the use of broadscale baiting. Aims We field-trialled and refined a collar for the CPE that was designed to allow red foxes to trigger CPEs, but prevent dingoes and medium–large-sized dogs from doing so. Methods We deployed uncollared and collared CPEs paired with camera-traps across two study areas in central Australia, and assessed which taxa triggered CPEs and whether the activity rates, behaviour and CPE triggering rates of five taxa (red foxes, wild dogs, feral cats (Felis catus), corvids (Corvus spp.), and varanids (Varanus spp.)) differed between CPEs with and those without collars. Key results With a simple modification to our original collar design, a red fox was able to trigger collared CPEs. Collared CPEs were triggered by wild dogs when they were set with the bait head 1 cm below the rim of the collar, but not when they were set with the bait head at 2 cm below the rim. Uncollared CPEs were triggered by wild dogs (97.03% of triggers), red foxes (1.98%) and corvids (0.99%). Activity rates of the study taxa towards CPEs did not differ between collared and uncollared CPEs. However, behavioural analyses suggested that red foxes and wild dogs showed more caution around collared CPEs. Conclusions We present proof-of-concept that deploying CPEs inside a collar increases the target specificity of this device by excluding wild dogs, while allowing red foxes to access the bait head. However, our data suggest that the addition of a collar may reduce interaction rates of red foxes and wild dogs with CPEs. Implications The collared CPE provides a control method for red foxes that reduces the risk to dingoes and other medium–large-sized dogs and may allow for greater landholder participation in red fox management.