Forest and snow rather than food or foe limit the distribution of a generalist mesocarnivore in winter

Investigating species responses to trophic interactions and abiotic factors is crucial to better understanding their ecology and creating effective management strategies. In carnivore communities, smaller species are often regulated by larger ones via top-down interference competition. Smaller subordinate carnivores can also be regulated by bottom-up and abiotic factors, such as the availability of important prey, habitat features, and climatic conditions. However, substantial ambiguity remains regarding the relative roles these complex factors play in shaping subordinate carnivore populations, especially during winter. To investigate this issue, we conducted a large-scale camera-trapping study (n = 197 sites distributed across a ~60,000 km2 landscape) using a balanced study design that sampled a gradient of forest disturbance and climatic conditions. We used dynamic occupancy modeling to examine the influences of top-down (interference competition), bottom-up (prey and habitat), and abiotic (climate) factors on a widespread, generalist subordinate carnivore, the red fox (Vulpes vulpes), in Maine, USA. Across three winters, we collected 107 red fox and 185 coyote (Canis latrans) daily detections, and 3875 snowshoe hare (Lepus americanus) detections. We found evidence for the top-down effects of coyotes on red fox detection probability and site colonization. However, contrary to theoretical expectations, the association between coyotes and red foxes was positive rather than negative. Snowshoe hares had a positive association with local extinction by red foxes, which also contrasts with prevailing theory given that snowshoe hares are an important winter prey of red foxes in this ecosystem. The intensity of forest disturbance and the proportion of conifer forest had negative effects on red fox occurrence and detection probability, while snow depth had a strong negative effect on site colonization. Together, these results suggest red foxes are limited more by abiotic and bottom-up factors related to habitat than by the top-down interference competition or primary prey availability in winter. Our study supports recent findings that bottom-up factors may shape carnivore distributions during less productive times of year. Our work also highlights how caution isneeded when extrapolating previous results from summer studies to winter, as the role of top-down and bottom-up factors may change seasonall

Spatial variation in leopard (Panthera pardus) site use across a gradient of anthropogenic pressure in Tanzania's Ruaha landscape

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

The many faces of fear:A synthesis of methodological variation in characterizing predation risk from carnivores

Predators affect prey by killing them directly (lethal effects) and by inducing costly antipredator behaviours in living prey (risk effects). Risk effects can strongly influence prey populations and cascade through trophic systems. A prerequisite for assessing risk effects is characterizing the spatiotemporal variation in predation risk. Risk effects research has experienced rapid growth in the last several decades. However, preliminary assessments of the resultant literature suggest that researchers characterize predation risk using a variety of techniques. The implications of this methodological variation for inference and comparability among studies have not been well recognized or formally synthesized. We couple a literature survey with a hierarchical framework, developed from established theory, to quantify the methodological variation in characterizing risk using carnivore-ungulate systems as a case study. Via this process, we documented 244 metrics of risk from 141 studies falling into at least 13 distinct subcategories within three broader categories. Both empirical and theoretical work suggest risk and its effects on prey constitute a complex, multi-dimensional process with expressions varying by spatiotemporal scale. Our survey suggests this multi-scale complexity is reflected in the literature as a whole but often underappreciated in any given study, which complicates comparability among studies and leads to an overemphasis on documenting the presence of risk effects rather than their mechanisms or scale of influence. We suggest risk metrics be placed in a more concrete conceptual framework to clarify inference surrounding risk effects and their cascading effects throughout ecosystems. We recommend studies (i) take a multi-scale approach to characterizing risk; (ii) explicitly consider 'true' predation risk (probability of predation per unit time); and (iii) use risk metrics that facilitate comparison among studies and the evaluation of multiple competing hypotheses. Addressing the pressing questions in risk effects research, including how, to what extent and on what scale they occur, requires leveraging the advantages of the many methods available to characterize risk while minimizing the confusion caused by variability in their application.The NSF Graduate Research Fellowship Program (RJM), the Michigan State University MasterCard Foundation Scholars Program (ABM), CNPq-Brasil (LA), and the University of Montana Boone and Crockett Program (JJM).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-26562018-07-30cs2017Centre for Wildlife Managemen

Physiological Stress Response of Captive White-Tailed Deer to Video Collars

Animal-borne video and environmental data collection systems (AVEDs) are an advanced form of biotelemetry that combines video with other sensors. As a proxy for physiological stress, we assessed fecal glucocorticoid metabolite (FGM) excretion in 7 white-tailed deer (Odocoileus virginianus) fitted with AVED dummy collars; 9 additional deer served as controls. We collected fecal samples over 3 2-week periods: pretreatment, treatment, and post-treatment periods. There were no differences in FGMs across time periods (F2,218 = 1.94, P = 0.147) and no difference between FGMs of control and treatment individuals (F1,14 = 0.72, P = 0.411). Fecal glucocorticoid metabolite excretion in AVED-collared deer was indistinguishable from uncollared animals and within the normal, baseline range for this species. Absence of an adrenal response to collaring suggested that AVED collaring does not induce physiological stress in deer

A framework for the Eltonian niche of humans

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.https://academic.oup.com/bioscience2022-05-26hj2022Mammal Research Institut

A REVIEW OF METHODS TO ESTIMATE AND MONITOR MOOSE DENSITY AND ABUNDANCE

Acquiring accurate and precise population parameters is fundamental to the ecological understanding and management and conservation of moose (Alces alces). Moose density is challenging to measure and often estimated using winter aerial surveys; however, numerous alternative approaches exist including harvest analysis, public observation, unpiloted aerial system (UAS) surveys, and camera trapping. Given recent developments in a number of field and analytical techniques, there is value in reviewing and synthesizing the strengths and limitations of monitoring methods to best evaluate their respective tradeoffs in management scenarios. We reviewed 89 studies that included 131 estimates or indices of moose density. As expected, aerial surveys were the most common method of obtaining a moose density estimate (58%) followed by use of public data (e.g., harvest records = 27%); more recent studies employed novel methods including UAS. Most estimates (64%) failed to account for imperfect detection of moose (i.e., “sightability”) and this tendency has not improved over time. Density estimates ranged from <0.1 to 10.6 moose/km2 (average = 0.7) and population precision, as measured by the 90% confidence interval, ranged from 6.5 to 120.0% of the density estimate (average = 37.4%). Correlations among estimates obtained for the same populations varied widely, with R2 values ranging from 0.02 to 0.99 (average = 0.58). Our review indicates that: 1) methods to estimate moose density have been dominated by aerial surveys but are diversifying, 2) precision of density estimates has been highly variable and on average lower than broadly accepted target benchmarks, and 3) many methods did not account for sightability and presumably underestimated moose density. We reflect on these trends and discuss how emerging methods, including camera trapping, UAS surveys, and integrated population modeling (IPM) can complement and improve traditional approaches. We suggest that no single “best” method exists, but rather the best method is one that accounts for sightability bias and yields target precision at reasonable cost, which vary by jurisdiction and goal

Clarifying niche width using broad-scale, hierarchial occupancy models: A case study with a recovering mesocarnivore.

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 (~50,000km2) 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

Energy-Aware Portable Video Communication System Design for Wildlife Activity Monitoring

Digital Object Identifier 10.1109/MCAS.2008.923007In this paper, we introduce our recent research and development effort on energy-efficient portable video communication system design for wildlife activity monitoring. The capability of seeing what an animal sees in the field is very important for wildlife activity monitoring and research. We design an integrated video and sensor system, called DeerCam and mount it on animals so as to collect important video and sensor data about their activities in the field. From the video and sensor data collected by DeerCam, wildlife researchers will be able to extract a wealth of scientific data for studying the behavior patterns of wildlife species and understanding the dynamic of wildlife systems. We present the system architecture of DeerCam, explain our system design goals, and discuss major design issues. One of the central challenges in DeerCam system design is energy minimization. We present a new approach for energy minimization of portable video devices: power-rate-distortion (P-R-D) analysis and optimization. We discuss various approaches to minimizing the energy consumption of DeerCam, which can be also applied to other portable video devices. Results demonstrate that, by incorporating the third dimension of power consumption into conventional rate-distortion (R-D) analysis, P-R-D analysis gives us one extra dimension of flexibility in resource allocation and energy minimization and allows us to significantly reduce energy consumption.This work was supported in part by National Science Foundation under grant DBI-0529082