Context: Camera traps are one of the most popular tools used to study wildlife worldwide. Numerous recent studies have evaluated the efficiency and effectiveness of camera traps as a research tool. Nonetheless, important aspects of camera-trap methodology remain in need of critical investigation. One such issue relates to camera-trap viewshed visibility, which is often compromised in the field by physical obstructions (e.g. trees) or topography (e.g. steep slopes). The loss of visibility due to these obstructions could affect wildlife detection rates, with associated implications for study inference and management application. Aims: We aimed to determine the effect of camera-trap viewshed obstruction on wildlife detection rates for a suite of eight North American species that vary in terms of ecology, commonness and body size. Methods: We deployed camera traps at 204 sites throughout an extensive semi-urban park system in Cleveland, Ohio, USA, from June to September 2016. At each site, we quantified camera-trap viewshed obstruction by using a cover-board design. We then modelled the effects of obstruction on wildlife detection rates for the eight focal species. Key results: We found that detection rates significantly decreased with an increasing viewshed obstruction for five of the eight species, including both larger and smaller mammal species (white-tailed deer, Odocoileus virginianus, and squirrels, Sciurus sp., respectively). The number of detections per week per camera decreased two-to three-fold as visibility at a camera site decreased from completely free of obstruction to mostly obstructed. Conclusions: These results imply that wildlife detection rates are influenced by site-level viewshed obstruction for a variety of species, and sometimes considerably so. Implications: Researchers using camera traps should address the potential for this effect to ensure robust inference from wildlife image data. Accounting for viewshed obstruction is critical when interpreting detection rates as indices of abundance or habitat use because variation in detection rate could be an artefact of site-level viewshed obstruction rather than due to underlying ecological processes.

Predation is a fundamental force exerting strong selective pressure on prey populations. Predators not only kill prey, triggering lethal effects, but also hunt prey which can induce risk effects. Foundational research has documented the importance of risk effects in predator-prey systems of arthropods, fish, birds, and rodents, among others. Risk effects research in carnivore-ungulate systems has expanded in the last 20 years. Presently, the degree to which this research mirrors the complexity of carnivore-ungulate trophic systems has been questioned. We synthesized this literature to quantify the tendency of risk effects research in carnivore-ungulate systems to be multispecies in design. Among the 170 studies that we reviewed, we found that on average just 1.26 (range = 1 to 5) carnivore species and 1.60 (range = 1 to 11) ungulate species were considered per study. Furthermore, 63% (n = 107 of 170) of the studies featured single predator - single prey research designs. These results contrast with the fact that all but one of the 82 carnivore-ungulate systems used this literature had multiple species of carnivores and/or ungulates. Thus, we detected a tendency to simplify complex systems. We relate these observations to the role of simplicity as: i) an underlying value of science (i.e., Occam's razor), ii) a cornerstone of predator-prey theory (e.g., Lotka-Volterra equations), and iii) part of the origins of risk effects research (i.e., experimental systems). Finally, we ground our discussion in the implications of this research for the conservation of carnivores and ungulates in the dynamic 21st century.

{Lions (Panthera leo) have experienced dramatic population declines in recent decades and today, inhabit just a fraction of their historic range. The reasons behind these declines are many, but conflict with humans, principally motivated by lion depredation of livestock, is among the most influential. Recent calls within the scientific community have identified that wicked problems like these should be addressed using interdisciplinary approaches. Here we examined the extent to which human-lion conflict research has been interdisciplinary. We conducted an extensive review of the literature and uncovered 88 papers, published between 1990 and 2015, that assessed human-lion interaction and the ecology of lions exposed to anthropogenic disturbance. While human-lion conflict research experienced near-exponential growth across this time period, the number of co-authors engaged in this research changed very little (mean = 3.28

Understanding large carnivore occurrence patterns in anthropogenic landscapes adjacent to protected areas is central to developing actions for species conservation in an increasingly human-dominated world. Among large carnivores, leopards (Panthera pardus) are the most widely distributed felid. Leopards occupying anthropogenic landscapes frequently come into conflict with humans, which often results in leopard mortality. Leopards' use of anthropogenic landscapes, and their frequent involvement with conflict, make them an insightful species for understanding the determinants of carnivore occurrence across human-dominated habitats. We evaluated the spatial variation in leopard site use across a multiple-use landscape in Tanzania's Ruaha landscape. Our study region encompassed i) Ruaha National Park, where human activities were restricted and sport hunting was prohibited; ii) the Pawaga-Idodi Wildlife Management Area, where wildlife sport hunting, wildlife poaching, and illegal pastoralism all occurred at relatively low levels; and iii) surrounding village lands where carnivores and other wildlife were frequently exposed to human-carnivore conflict related-killings and agricultural habitat conversion and development. We investigated leopard occurrence across the study region via an extensive camera trapping network. We estimated site use as a function of environmental (i.e. habitat and anthropogenic) variables using occupancy models within a Bayesian framework. We observed a steady decline in leopard site use with downgrading protected area status from the national park to the Wildlife Management Area and village lands. Our findings suggest that human-related activities such as increased livestock presence and proximity to human households exerted stronger influence than prey availability on leopard site use, and were the major limiting factors of leopard distribution across the gradient of human pressure, especially in the village lands outside Ruaha National Park. Overall, our study provides valuable information about the determinants of spatial distribution of leopards in human-dominated landscapes that can help inform conservation strategies in the borderlands adjacent to protected areas.

A species' habitat niche width informs its position on the generalist–specialist continuum, which is central to life-history theory and crucial to conservation planning. However, assessments of niche width are often based on local-scale studies or qualitative descriptions rather than broad, quantitative assessments conducted in heterogeneous landscapes. Here, we show how broad-scale, hierarchical occupancy models can clarify a species' niche width and degree of habitat specialism by evaluating the woodland-specialist classification of the European pine marten Martes martes. We deployed 526 camera-trap stations at 27 sites throughout a vast extent ($\sim$50 000 km2) in Scotland and modeled pine marten occupancy as a function of habitat characteristics using a hierarchical Bayesian analysis. Our model was flexible to trap happiness due to baiting at camera traps and accounted for spatial autocorrelation among and imperfect detection at camera-trap stations. We detected a positive association between pine marten occupancy probability and wooded habitats. However, pine marten occupancy probability was also high in numerous non-wooded habitats, including agricultural land, heather and heather grassland, semi-natural grassland and areas near anthropogenic structures. Our study is the first to record high pine marten occupancy in open habitats at broad spatial scales and thereby corroborates recent smaller scale indications that pine martens are more of a habitat generalist than previously thought. Our results guide ongoing conservation efforts by identifying that pine martens are not strict woodland specialists, but rather inhabit a mosaic of habitat types in the landscape. More broadly, our case study exemplifies how coupling hierarchical occupancy models with large-scale experimental designs can clarify a species' niche width and associated position on the generalist–specialist continuum.

he 'landscape of fear' model, recently advanced in research on the non-lethal effects of carnivores on ungulates, predicts that prey will exhibit detectable antipredator behavior not only during risky times (i.e., predators in close proximity) but also in risky places (i.e., habitat where predators kill prey or tend to occur). Aggregation is an important antipredator response in numerous ungulate species, making it a useful metric to evaluate the strength and scope of the landscape of fear in a multi-carnivore, multi-ungulate system. We conducted ungulate surveys over a two-year period in South Africa to test the influence of three broad-scale sources of variation in the landscape on spatial patterns in aggregation: 1) habitat structure, 2) where carnivores tended to occur (i.e., population-level utilization distributions) and 3) where carnivores tended to kill ungulate prey (i.e., probabilistic kill site maps). We analyzed spatial variation in aggregation for six ungulate species exposed to predation from recently reintroduced lion (Panthera leo) and spotted hyena (Crocuta crocuta). Although we did detect larger aggregations of ungulates in 'risky places', these effects existed primarily for smaller-bodied (<150kg) ungulates and were relatively moderate (change of less than or equal to 4 individuals across all habitats). In comparison, ungulate aggregations tended to increase at a slightly lower rate in habitat that was more open. Lion, an ambush (stalking) carnivore, had stronger influence on ungulate aggregation than hyena, an active (coursing) carnivore. In addition, places where lions tended to kill prey more strongly affected ungulate aggregation than places where lions tended to occur, but an opposing pattern existed for hyena. Our study reveals heterogeneity in the landscape of fear and suggests broad-scale risk effects following carnivore reintroduction only moderately influence ungulate aggregation size and vary considerably by predator hunting mode, type of predation risk, and prey species. Read More: http://www.esajournals.org/doi/abs/10.1890/15-0707.1

Over the past three decades, technological advances for monitoring wild animals have expanded the ability of ecologists to study animal behavior and space use. Currently, researchers are deploying animal-borne video and environmental data collection systems (AVEDs), which enable researchers to see what the animal sees in the field. AVEDs record fine-scale movements as well as features of the surrounding environment and thus provide essential context for understanding animal decisions and interactions with other individuals. These fine-scale data are often crucial for understanding potential conservation threats to species of concern. Here, we discuss the development and research potential offered by AVEDs. The benefits of AVEDs are greatest in hypothesis-driven studies that require a fine-scale perspective that other technologies cannot offer.