Individual decisions regarding how, why and when organisms interact with one another and with their environment scale up to shape patterns and processes in communities. Recent evidence has firmly established the prevalence of intraspecific variation in nature and its relevance in community ecology, yet challenges associated with collecting data on large numbers of individual conspecifics and heterospecifics have hampered integration of individual variation into community ecology. Nevertheless, recent technological and statistical advances in GPS-tracking, remote sensing and behavioural ecology offer a toolbox for integrating intraspecific variation into community processes. More than simply describing where organisms go, movement data provide unique information about interactions and environmental associations from which a true individual-to-community framework can be built. By linking the movement paths of both conspecifics and heterospecifics with environmental data, ecologists can now simultaneously quantify intraspecific and interspecific variation regarding the Eltonian (biotic interactions) and Grinnellian (environmental conditions) factors underpinning community assemblage and dynamics, yet substantial logistical and analytical challenges must be addressed for these approaches to realize their full potential. Across communities, empirical integration of Eltonian and Grinnellian factors can support conservation applications and reveal metacommunity dynamics via tracking-based dispersal data. As the logistical and analytical challenges associated with multi-species tracking are surmounted, we envision a future where individual movements and their ecological and environmental signatures will bring resolution to many enduring issues in community ecology.

Aim: Understanding the range-wide distribution and abundance of species is critical for their conservation and management. Grey foxes (Urocyon cinereoargenteus) are an understudied, low-density mesocarnivore with a broad geographic range. However, the factors that underlie this broad distribution are poorly understood and large-scale analyses of this species' range and ecological niche are lacking. Location: We modelled the probability and intensity of site use for grey foxes at two spatial scales using a coordinated survey of 1485 camera traps across the contiguous United States in 2019. Methods: We used Bayesian occupancy modelling and post hoc species interaction comparisons to evaluate factors hypothesized to affect grey fox site use, including habitat, anthropogenic effects, and intraguild interactions. Results: Our results showed that the presence of bobcats (Lynx rufus) and striped skunks (Mephitis mephitis), as well as forest variables, had positive associations with grey fox site use. Surprisingly, we found no support for negative effects on grey fox space use from dominant competitors (coyotes, Canis latrans, or pumas, Puma concolor), and a complete lack of effects from urbanization metrics and gross primary productivity. We did, however, find a consistent negative association with red foxes (Vulpes vulpes), which is the most ecologically and morphologically similar competitor of grey foxes. Main conclusions: Taken together, these results imply that grey fox distribution is not limited by dominant carnivores or anthropogenic pressure. Rather, this species seems to occupy a unique niche across its broad range by exploiting diverse forest habitats shared with less ecologically similar competitors (striped skunks and raccoons, Procyon lotor), while being somewhat limited by a competitor occupying a similar ecological niche (red foxes). Our study highlights the value of broad-scale approaches for evaluating factors influencing the distribution and abundance of understudied species, as local dynamics might fail to manifest across geographic ranges.

In promoting coexistence, sympatric species often partition shared resources along spatio-temporal domains. Similarly sized and phylogenetically close species, for instance, partition the times of day in which they are active to limit interference competition. Given that variation in species body mass has evolutionary underpinnings, species activity levels (time spent active in a 24-h daily cycle) within animal communities might be structured by phylogeny. However, few studies have tested this hypothesis across animal communities, and none among medium-sized to large mammals. We quantified the relative contributions of phylogeny and body mass in predicting activity levels in a community of 22 sympatric mammal species in Murchison Falls National Park, Uganda. We show that phylogeny is a stronger predictor of species activity levels than body mass. Our findings provide empirical evidence for the phylogenetic structuring of mammal activity in diverse communities. More broadly, our results suggest that evolutionary relationships mask allometry in predicting species traits in diverse animal communities.

Apex predators can shape communities via cascading top–down effects, but the degree to which such effects depend on predator life history traits is largely unknown. Within carnivore guilds, complex hierarchies of dominance facilitate coexistence, whereby subordinate species avoid dominant counterparts by partitioning space, time, or both. We investigated whether a major life history trait (hibernation) in an apex carnivore (black bears Ursus americanus) mediated its top–down effects on the spatio-temporal dynamics of three sympatric mesocarnivore species (coyotes Canis latrans, bobcats Lynx rufus, and gray foxes Urocyon cinereoargenteus) across a 15,000 km2 landscape in the western USA. We compared top–down, bottom–up, and environmental effects on these mesocarnivores using an integrated modeling approach. Black bears exerted top–down effects that varied as a function of hibernation and were stronger than bottom–up or environmental impacts. High black bear activity in summer and fall appeared to buffer the most subordinate mesocarnivore (gray foxes) from competition with dominant mesocarnivores (coyotes and bobcats), which were in turn released by black bear hibernation in winter and early spring. The mesocarnivore responses occurred in space (i.e., altered occupancy and site visitation intensity) rather than time (i.e., diel activity patterns unaffected). These results suggest that the spatio-temporal dynamics of mesocarnivores in this system were principally shaped by a spatial predator cascade of interference competition mediated by black bear hibernation. Thus, certain life history traits of apex predators might facilitate coexistence among competing species over broad time scales, with complex implications for lower trophic levels.

Recent research has highlighted several influential roles that humans play in ecosystems, including that of a superpredator, hyperkeystone species, and niche constructor. This work has begun to describe the Eltonian niche of humans, which encompasses humanity's cumulative ecological and evolutionary roles in trophic systems. However, we lack a unifying framework that brings together these strands of research, links them to ecoevolutionary and sociocultural theory, and identifies current research needs. In this article, we present such a framework in hope of facilitating a more holistic approach to operationalizing human roles in trophic systems across an increasingly anthropogenic biosphere. The framework underscores how humans play numerous nuanced roles in trophic systems, from top-down to bottom-up, that entail not only pernicious effects but also benefits for many nonhuman species. Such a nuanced view of the Eltonian niche of humans is important for understanding complex social–ecological system functioning and enacting effective policies and conservation measures.

Pastoralists and their livestock have long competed with wildlife over access to grazing on shared rangelands. In the dynamic 21st century however, the configuration and quality of these rangelands is changing rapidly. Climate change processes, human range expansion, and the fragmentation and degradation of rangeland habitat have increased competition between pastoralist livestock and wildlife. Interactions of this type are particularly apparent in East Africa, and perhaps most obvious in northern Kenya. In 2017, following months of intense drought, a pastoralist incursion of a protected area (Loisaba Conservancy) occurred in Laikipia County, Kenya. An estimated 40,000 livestock were herded onto the conservancy by armed pastoralists where the cattle were grazed for approximately three months. Using 53 camera trap sites across the 226 km2 conservancy, we quantified spatial patterns in site visitation rates (via spatially-explicit, temporally-dynamic Bayesian models) for seven species of large mammalian herbivores in the three-month period directly before, during, and after the incursion. We detected significant changes in space use of all large mammalian herbivores during the incursion. Furthermore, these patterns did not return to their pre-incursion state in the three-month period after the pastoralists and their livestock left the conservancy. Thus, in addition to reduced site vitiation rates for these large mammalian herbivores, we also detected considerable displacement in response to the livestock incursion. Our results illustrate that pastoralist incursions can cause large-scale disruptions of wildlife space use, supporting the notion that livestock can competitively exclude large mammalian herbivores from grazing access. We discuss the implications of this research for applied management decisions designed to alleviate competition among wildlife and pastoralist livestock for the benefit of wildlife conservation and pastoralist well-being.

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.