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For 90 years, the American Society of Mammalogists (ASM) has made science-based challenges to widespread lethal control of native mammals, particularly by the United States federal government targeting carnivores in the western states. A consensus is emerging among ecologists that extirpated, depleted, and destabilized populations of large predators are negatively affecting the biodiversity and resilience of ecosystems. This Special Feature developed from a thematic session on predator control at ASM's 2013 annual meeting, and in it we present data and arguments from the perspectives of ecology, wildlife biology and management, social science, ethics, and law and policy showing that nonlethal methods of preventing depredation of livestock by large carnivores may be more effective, more defensible on ecological, legal, and wildlife-policy grounds, and more tolerated by society than lethal methods, and that total mortality rates for a large carnivore may be driven higher than previously assumed by human causes that are often underestimated.

Coyotes (Canis latrans) are the top predator of livestock in the contiguous United States. Developing more effective nonlethal tools to prevent coyote depredation will facilitate coexistence between livestock producers and coyotes. Fladry is a nonlethal deterrent designed to defend livestock by creating a visual barrier to wolves (C. lupus). Fladry may also be effective with coyotes, but large gap spacing between flags may reduce its efficacy. To address this issue, we performed 2 experiments on captive coyotes using fladry modified to reduce gap spacing at the U.S. Department of Agriculture, Predator Research Facility in Millville, Utah, USA, during 2015–2016 and 2017–2018. In 2015–2016, we tested 2 styles for attaching flags (top-knot and shower-curtain) to the rope-line that reduce gaps by preventing coiling of individual flags. In 2017–2018, we tested the efficacy of gap spacing (27.9 cm vs. 45.7 cm) between flags for preventing coyote crossings. For both tests, we compared the time until coyotes crossed the fladry between treatment types. We found no differences in time to crossing between the 2 attachment designs. In our second experiment, fladry with smaller gaps between flags had greater efficacy of preventing coyote crossings than did fladry with larger gaps. Our results also indicated that for each additional minute coyotes spent interacting with fladry overall (i.e., increased persistent behavior), survival of the barrier decreased. These results suggest that persistent coyotes may overcome neophobia more rapidly than coyotes that do not exhibit persistent behaviors. Furthermore, use of top-knot fladry and coyote-width spacing will increase protection of livestock from coyotes.

Predation threatens the economic viability of sheep operations in the United States. Many producers recognize the need to complement lethal control methods with nonlethal strategies such as the use of livestock guardian dogs (LGDs), but little information exists on benefits and costs. We report on a comprehensive benefit–cost analysis of the decision to incorporate LGDs onto a sheep operation in Mendocino County, California, USA, based on data collected during 2013–2017, where livestock predation by coyotes (Canis latrans) has been a persistent problem. We estimated that for a representative sheep operation with a breeding flock of 500 adult females (ewes), the use of 5 LGDs reduced lambs and ewes lost to coyote predation by 43% and 25%, respectively, for a total savings of US$16,200 over 7 years. However, we found that costs, which included acquisition and maintenance expenses, exceed benefits of this investment over the 7-year useful life of LGDs by US$13,413. Our results inform the adoption of LGDs, demonstrating that LGDs are only cost-effective for certain types of operations, namely those where LGDs are able to achieve high rates of predator protection efficacy.

Foraging mammalian predators face a myriad of odors from potential prey. To be efficient, they must focus on rewarding odors while ignoring consistently unrewarding ones. This may be exploited as a nonlethal conservation tool if predators can be deceived into ignoring odors of vulnerable secondary prey. To explore critical design components and assess the potential gains to prey survival of this technique, we created an individual-based model that simulated the hunting behavior of three introduced mammalian predators on one of their secondary prey (a migratory shorebird) in the South Island of New Zealand. Within this model, we heuristically assessed the outcome of habituating the predators to human-deployed unrewarding bird odors before the bird’s arrival at their breeding grounds, i.e., the predators were “primed.” Using known home range sizes and probabilities of predators interacting with food lures, our model suggests that wide-ranging predators should encounter a relatively large number of odor points (between 10 and 115) during 27 d of priming when odor is deployed within high-resolution grids (100–150 m). Using this information, we then modeled the effect of different habituation curves (exponential and sigmoidal) on the probability of predators depredating shorebird nests. Our results show that important gains in nest survival can be achieved regardless of the shape of the habituation curve, but particularly if predators are fast olfactory learners (exponential curve), and even if some level of dishabituation occurs after prey become available. Predictions from our model can inform the amount and pattern in which olfactory stimuli need to be deployed in the field to optimize encounters by predators, and the relative gains that can be expected from reduced predation pressure on secondary prey under different scenarios of predator learning. Habituating predators to odors of threatened secondary prey may have particular efficacy as a conservation tool in areas where lethal predator control is not possible or ethical, or where even low predator densities can be detrimental to prey survival. Our approach is also relevant for determining interaction probabilities for devices other than odor points, such as bait stations and camera traps.

To mitigate coyote (Canis latrans) introgression in the wild red wolf (Canis rufus) genome, the United States Fish and Wildlife Service (USFWS) Red Wolf Recovery Program used a combination of reproductive sterilization and lethal removal of coyotes to minimize hybridization and increase the endangered red wolf population. Although sterilization assisted in limiting coyote introgression to ≤4% in the wild red wolf genome, its potential negative effect on coyote and hybrid abundance and density is unknown. Using long‐term capture–mark–recapture and radio‐telemetry data collected on red wolves, coyotes, and hybrids under the USFWS Red Wolf Adaptive Management Plan implemented during 2000–2013, we explored three areas of research: (1) spatial modeling to correlate land cover characteristics with the relative probabilities of capture for red wolves, coyotes, and hybrids; (2) survival analysis of radio‐marked canids; and (3) annual population estimates for the three Canis taxa. We detected no differences in the relative probability of capture among Canis taxa. Red wolves, coyotes, and hybrids were most frequently captured in areas proximate to road networks with low canopy cover (i.e., cropland) and away from coastal bottomland forests. Annual apparent survival for red wolves and hybrids was greater than survival for coyotes; however, wolves and hybrids exhibited similar annual survival. Mortality of coyotes and hybrids was predominately attributed to deliberate take through lethal control by the USFWS biologists and harvest by hunters and trappers. We observed annual densities of coyotes ranging between 2.5 and 21.5 coyotes/1000 km2, with densities annually increasing during 2005–2013 when the red wolf population plateaued before declining after 2013. Despite the increase in coyote density, our density estimates are less than most estimates reported throughout the coyote's geographic range, and similar to those reported in areas where coyote populations are limited by extreme environments such as their northern range limits in Alaska, United States, and Canada. Our findings indicate that red wolf presence and federal management of coyotes using fertility control may have limited coyote densities in northeastern North Carolina.

Conflict between livestock producers and wild predators is a central driver of large predator declines and simultaneously may imperil the lives and livelihoods of livestock producers. There is a growing recognition that livestock–predator conflict is a socio‐ecological problem, but few case studies exist to guide conflict research and management from this point of view. Here we present a case study of coyote‐sheep predation on a California ranch in which we combine methods from the rapidly growing field of predation risk modeling with participatory mapping of perceptions of predation risk. Our findings reveal an important selection bias that may occur when producer perceptions and decisions are excluded from ecological methods of studying conflict. We further demonstrate how producer inputs, participatory mapping, and ecological modeling of conflict can inform one another in understanding patterns, drivers, and management opportunities for livestock–predator conflict. Finally, we make recommendations for improving the interoperability of ecological and social data about predation risk. Collectively our methods offer a socio‐ecological approach that fills important research gaps and offers guidance to future research.

I argue that the terms lethal control, nonlethal control, and live trap are no longer sufficiently precise for continued use in the scientific community. Their continued use confuses the public and allows animal protectionists to use them as cudgels in political discourse. Alternative terms are recommended to resolve the semantic and subsequent political issues surrounding the traditional terms.

Nonlethal deterrents against carnivores are important components to protecting livestock and conserving carnivore populations. However, the performance of the visual deterrent called fladry, a historical tool used to defend livestock from carnivores, is often hindered by design flaws that eventually reduce its effectiveness. Our purpose was to identify a fladry design that reduces coiling (i.e., wrapping of individual flags tight to the rope from which they hang) and maintains free movement of the deterrent in the wind. We created 6 new designs, replicated designs using 2 materials (nylon and marine vinyl), and compared them with the design most commonly used today—where flags were sewn directly onto the line along which they are strung. We conducted the study during January–February 2014 at the U.S. Department of Agriculture, Wildlife Services, Predator Research Facility in Millville, Utah, USA. Fladry made of marine vinyl and attached via 2 of our 6 designs showed the least amount of coiling, were relatively easy to construct, and did not result in significant additional costs. The 2 designs were shower curtain, where the flags are attached via circular links, and knotted, where a knot is tied in the flag below its point of attachment. We suggest users of nylon fladry modify it to one of these designs and advise new users to consider a heavier (e.g., marine vinyl) material.

Several forms of nonlethal management exist, but fi eld testing is problematic, and few such techniques have been tested on free-ranging wolves (Canis lupus) or other predators. We tested fladry in the eastern Upper Peninsula of Michigan during the summers of 2004 and 2005 on treatment farms and control farms. Wolf visitation inside pastures, compared to those outside pastures, was less on fladry-protected farms (U = 45, n = 7, P = 0.004); whereas, we found no difference in wolf visitation inside and outside of pastures on control farms (U = 30, n = 7, P = 0.24). We found no difference in coyote (Canis latrans) visitation inside and outside of pastures on both treatment (U = 29.5, n = 7, P = 0.26) and control farms (U = 31.5, n = 7, P = 0.19). In our study, fladry deterred wolves from using livestock areas. Fladry was not effective for coyotes. Fladry may provide livestock owners and management agencies a temporarily effective, nonlethal management tool for reducing wolf-caused depredation of livestock; however, labor and equipment costs can be substantial.

Sterilization is an effective nonlethal tool to reduce livestock depredation by coyotes (Canis latrans) because adults without pups to provision are less likely to kill livestock. Surgical sterilization is costly and invasive, so identifying nonsurgical methods for canids that allow wide-scale application is important. We conducted a preliminary assessment of 2 types of reproductive inhibitors (gonadotropin releasing hormone [GnRH] vaccine and deslorelin, a GnRH agonist) on coyote reproductive capabilities. We treated captive coyotes with a GnRH vaccine (n = 6 males, n = 6 females) or deslorelin (n = 6 males), measured number of litters and pups born, and compared their behavior and hormone levels to captive coyote pairs in which the male was surgically vasectomized (n = 6). At least half of the pairs receiving treatment with either of the nonsurgical reproductive inhibitors produced pups, and litter size was larger than expected compared to historical records. Male coyotes treated with deslorelin showed decreased testosterone levels, whereas there was no difference in testosterone levels in males treated with GnRH vaccine compared to controls. Behavior did not differ between any groups. Despite the lack of efficacy of either reproductive inhibitor tested, our research suggests that hormonal alterations that disrupt reproduction of coyotes are unlikely to negatively affect behavior, and further investigation of nonsurgical reproductive inhibitors for wild canids is warranted.