Reducing nontarget recaptures of an endangered predator using conditioned aversion and reward removal

Abstract

Summary 1.Live-trapping is a fundamental tool in the study of wildlife species and populations. Capture of nontarget species is an inherent side-effect of trapping animals that is inefficient and potentially detrimental to individuals and populations. Reducing recapture of nontarget species will increase the efficiency of long-term studies and projects, and minimize unwanted impacts. 2. During the initial stages of a 3-year feral cat Felis catus control programme on San Clemente Island, California, USA, we experienced high recapture rates of nontarget endangered San Clemente Island foxes Urocyon littoralis clementae, impacting project efficiency and potentially foxes. 3. We investigated whether we could modify our baiting strategy to reduce fox recaptures using behavioural modification techniques, while simultaneously maintaining the ability to capture feral cats. We tested two strategies, aversive conditioning and reward removal, to reduce fox recapture rates. 4. Using lithium chloride (LC) as an aversive agent, we reduced fox recapture rates more than 10 times compared with rates using control bait. Using the reward removal technique, we reduced fox recapture rates almost 20 times compared with control baits. Neither behavioural modification technique deterred cats from entering traps, and our results suggest that by reducing fox recaptures, we improved our ability to capture cats. 5. Synthesis and applications. These novel baiting strategies have wide applicability in wildlife research and management. The efficiency of long-term monitoring or control programmes may be enhanced by discouraging recapture of 'trap happy' animals. Potential impacts to threatened species confined in traps could be minimized by reducing recaptures. Sampling of rare species in biodiversity studies could be improved by reducing recapture of competitively superior or numerically dominant species.

Variation of prey responses to cues from a mesopredator and an apex predator

“…Habituation to predator scented foraging trays is therefore possible, but has not been described previously. Recapture of 'trap-happy' individuals often occurs in trapping studies (Phillips & Winchell 2011), and a similar phenomenon may have occurred in the current study, with rock rats repeatedly visiting trays due to an association of the apparatus with food.…”

Can Cage-Trap Performance in Capturing Red Foxes Be Improved by Using Different Baits and Scent Attractants?

“…For example, Short et al (2012) showed that a careful neck snare design improved selectivity without sacrificing efficiency to capture red foxes in the UK. In addition, modifying the cage-trap baiting strategy significantly reduced the recapture rate of an endangered non-target fox species in an island in California (USA), maintaining the capture rate of targeted feral cats (Phillips & Winchell 2011). In our study, the combination of live bait and fox urine improved cage-trap efficiency to capture red foxes, which would likely satisfy hunters' demand.…”

Comparative cognition for conservationists

“…Animal conservation incorporates diverse policies and wildlife management methods, and some, including reintroductions [4] , trapping [5] , invasive species mitigation [6] , and deterrents [7] rely on manipulating animals’ behavioural responses. These interventions could be improved with insights from comparative cognition.…”

“…However, with careful planning, operant conditioning can be a highly effective conservation tool. For example, wildlife managers successfully reduced trappings of native species while managing feral cat populations through aversive conditioning by fostering associations between a negative cue (nausea-inducing chemicals in trapping baits) and the experience of feeding in the trap [5] .…”