Gold-standard experiments to deter predators from attacking livestock.

Abstract

We summarize qualitative data on experiences with gold standard, randomized, controlled trials with crossover design to evaluate the effectiveness of non-lethal methods to reduce carnivore attacks on domestic animals in four countries. We synthesize lessons learned in four categories: Experiences with randomized, controlled trials (RCTs), Design recommendations, Effectiveness of non-lethal methods to prevent wild carnivore predation on working livestock, and Conclusions. We place these in a global context with similar trials. We discuss gaps in evidence that should motivate investments in research and precautions among decision-makers at all levels. 1. The long-held belief that randomized, controlled trials (RCTs) are impossible in wild ecosystems with working livestock is laid to rest. 2. Crossover designs reduce most confounding variables between subjects and strengthen inference beyond the gold-standard of RCTs, yet we describe limitations precisely. 3. Non-lethal methods can be effective in preventing carnivore approaches and attacks on working livestock in fenced pastures or open rangelands. The relationship between approaches and attacks remains uncertain. 4. Lethal methods of predator control have been subjected to less robust study designs that suggest mixed results including increases in livestock losses. 5. Non-lethal methods promise the elusive triple-win for wildlife, domestic animals, and livelihoods.