Livestock owners traditionally use various non‐lethal and lethal methods to protect their domestic animals from wild predators. However, many of these methods are implemented without first considering experimental evidence of their effectiveness in mitigating predation‐related threats or avoiding ecological degradation. To inform future policy and research on predators, we systematically evaluated evidence for interventions against carnivore (canid, felid, and ursid) predation on livestock in North American and European farms. We also reviewed a selection of tests from other continents to help assess the global generality of our findings. Twelve published tests – representing five non‐lethal methods and 7 lethal methods – met the accepted standard of scientific inference (random assignment or quasi‐experimental case‐control) without bias in sampling, treatment, measurement, or reporting. Of those twelve, prevention of livestock predation was demonstrated in six tests (four non‐lethal and two lethal), whereas counterintuitive increases in predation were shown in two tests (zero non‐lethal and two lethal); the remaining four (one non‐lethal and three lethal) showed no effect on predation. Only two non‐lethal methods (one associated with livestock‐guarding dogs and the other with a visual deterrent termed “fladry”) assigned treatments randomly, provided reliable inference, and demonstrated preventive effects. We recommend that policy makers suspend predator control efforts that lack evidence for functional effectiveness and that scientists focus on stringent standards of evidence in tests of predator control.
Carnivore predation on livestock often leads people to retaliate. Persecution by humans has contributed strongly to global endangerment of carnivores. Preventing livestock losses would help to achieve three goals common to many human societies: preserve nature, protect animal welfare, and safeguard human livelihoods. Between 2016 and 2018, four independent reviews evaluated >40 years of research on lethal and nonlethal interventions for reducing predation on livestock. From 114 studies, we find a striking conclusion: scarce quantitative comparisons of interventions and scarce comparisons against experimental controls preclude strong inference about the effectiveness of methods. For wise investment of public resources in protecting livestock and carnivores, evidence of effectiveness should be a prerequisite to policy making or large-scale funding of any method or, at a minimum, should be measured during implementation. An appropriate evidence base is needed, and we recommend a coalition of scientists and managers be formed to establish and encourage use of consistent standards in future experimental evaluations.
Livestock depredation has implications for conservation and agronomy; it can be costly for farmers and can prompt retaliatory killing of carnivores. Lethal control measures are readily available and are reportedly perceived to be cheaper, more practical and more effective than non-lethal methods. However, the costs and efficacy of lethal vs non-lethal approaches have rarely been compared formally. We conducted a 3-year study on 11 South African livestock farms, examining costs and benefits of lethal and non-lethal conflict mitigation methods. Farmers used existing lethal control in the first year and switched to guardian animals (dogs Canis familiaris and alpacas Lama pacos) or livestock protection collars for the following 2 years. During the first year the mean cost of livestock protection was USD 3.30 per head of stock and the mean cost of depredation was USD 20.11 per head of stock. In the first year of non-lethal control the combined implementation and running costs were similar to those of lethal control (USD 3.08 per head). However, the mean cost of depredation decreased by 69.3%, to USD 6.52 per head. In the second year of non-lethal control the running costs (USD 0.43 per head) were significantly lower than in previous years and depredation costs decreased further, to USD 5.49 per head. Our results suggest that non-lethal methods of human-wildlife conflict mitigation can reduce depredation and can be economically advantageous compared to lethal methods of predator control.
Estimating species population density directly contributes to the conservation of species. As keystone species, carnivores are important to conserve; however, estimating density of wide‐ranging, elusive and solitary carnivores has proven difficult. The leopard (Panthera pardus) is the last large free‐roaming top carnivore in South Africa, and no formal density study had been conducted across the Eastern and Western Cape. We estimated leopard density and abundance using GPS data from 21 collared leopards and a spatially explicit capture–mark–recapture (SECR) method with camera trap survey data. Four regional sites were surveyed using 173 camera trap locations over 15,390 camera trap days, capturing 740 leopard images of which 77 individuals were identified. SECR averaged 0.95 leopards/100 km2 and the two GPS methods averaged 1 and 1.11 leopards/100 km2. Based on predicted available leopard habitat for the region, leopard abundance was estimated between 467 (±112.8) and 553 (±168.8) in the Western Cape and between 365 (±93.2) and 430 (±139.9) in the Eastern Cape. Discrepancies in density estimates can be complex stemming from biological behaviour, anthropogenic factors and prey density. However, our estimates appear to show relatively little variation, suggesting that SECR methods and GPS data capture the population density estimates of the species well.
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