Intraguild relationships between sympatric predators exposed to lethal control: predator manipulation experiments

• Main Authors: Allen, Benjamin L., Allen, Lee R., Engeman, Richard M., Leung, Luke K.-P.
• Format: Text
• Language: unknown
• Published: DigitalCommons@University of Nebraska - Lincoln 2013
• Subjects: Canis lupus dingo; Dingo; European red fox; Felis catus; Feral cat; Mesopredator release; Monitor lizard; Poison baiting; Predator control; Trophic cascade; Varanus spp; Vulpes vulpes; Life Sciences; Canis lupus
• Online Access: https://digitalcommons.unl.edu/icwdm_usdanwrc/1439; https://digitalcommons.unl.edu/context/icwdm_usdanwrc/article/2437/viewcontent/Allen_FZ_2013_Intraguild_relationships.pdf

Introduction: Terrestrial top-predators are expected to regulate and stabilise food webs through their consumptive and non-consumptive effects on sympatric mesopredators and prey. The lethal control of top-predators has therefore been predicted to inhibit top-predator function, generate the release of mesopredators and indirectly harm native fauna through trophic cascade effects. Understanding the outcomes of lethal control on interactions within terrestrial predator guilds is important for zoologists, conservation biologists and wildlife managers. However, few studies have the capacity to test these predictions experimentally, and no such studies have previously been conducted on the eclectic suite of native and exotic, mammalian and reptilian taxa we simultaneously assess. We conducted a series of landscape-scale, multi-year, manipulative experiments at nine sites spanning five ecosystem types across the Australian continental rangelands to investigate the responses of mesopredators (red foxes, feral cats and goannas) to contemporary poison-baiting programs intended to control top-predators (dingoes) for livestock protection. Result: Short-term behavioural releases of mesopredators were not apparent, and in almost all cases, the three mesopredators we assessed were in similar or greater abundance in unbaited areas relative to baited areas, with mesopredator abundance trends typically either uncorrelated or positively correlated with top-predator abundance trends over time. The exotic mammals and native reptile we assessed responded similarly (poorly) to top-predator population manipulation. This is because poison baits were taken by multiple target and non-target predators and top-predator populations quickly recovered to pre-control levels, thus reducing the overall impact of baiting on top-predators and averting a trophic cascade. Conclusions: These results are in accord with other predator manipulation experiments conducted worldwide, and suggest that Australian populations of native prey fauna at lower ...