Camera Trap Sites Research Articles

SNAPSHOT USA 2019: a coordinated national camera trap survey of the United States.

With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the United States. For our first annual survey, we compiled data across all 50 states during a 14-week period (17 August-24 November of 2019). We sampled wildlife at 1,509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian's eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera trap survey of the United States. All of the 2019 survey data are made available herein. We are currently repeating surveys in fall 2020, opening up the opportunity to other institutions and cooperators to expand coverage of all the urban-wild gradients and ecophysiographic regions of the country. Future data will be available as the database is updated at eMammal.si.edu/snapshot-usa, as will future data paper submissions. These data will be useful for local and macroecological research including the examination of community assembly, effects of environmental and anthropogenic landscape variables, effects of fragmentation and extinction debt dynamics, as well as species-specific population dynamics and conservation action plans. There are no copyright restrictions; please cite this paper when using the data for publication.

Jaguars and pumas exhibit distinct spatiotemporal responses to human disturbances in Colombia’s most imperiled ecoregion

Abstract Coexistence of sympatric felids is facilitated by mutual avoidance and the partitioning of habitats, prey, and time. Anthropogenic disturbances disrupt this coexistence in fragmented landscapes, potentially triggering cascading influences in ecological communities. We used photographic data from 8,717 trap nights (November 2014–June 2016) at 87 camera trap sites in Colombia’s middle Magdalena River basin to compare spatiotemporal overlap among jaguars (Panthera onca), pumas (Puma concolor), their prey, and humans, at sites of high and low disturbance, as determined by the human influence index. Human disturbance events (e.g., domestic dogs, livestock, and humans, including armed hunters) comprised 38% of all photographs at high disturbance sites and 29% of all photographs at low disturbance sites. Differential spatiotemporal overlaps were recorded between felids and their prey at high versus low disturbance sites, with jaguars exhibiting only 13% temporal overlap with humans at high disturbance sites. Among prey, temporal overlap was greater than spatial overlap for both felids across the study area. Compared to jaguars, pumas displayed more temporal overlap with all anthropogenic variables and more spatial overlap with most anthropogenic variables, suggesting lesser sensitivity to human disturbances. This study provides the first insights into the responses of a threatened large carnivore, jaguar, to camera trap-derived human disturbance variables in an unprotected landscape. It also highlights the importance of using multiple disturbance types for evaluating human impacts on large carnivores.

Landscape-level changes to large mammal space use in response to a pastoralist incursion

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.

Assessing the activity pattern overlap among leopards (Panthera pardus), potential prey and competitors in a complex landscape in Tanzania

AbstractStudying activity patterns and temporal overlap among carnivores and their putative prey is difficult because of their secretive and elusive nature. With large carnivores declining worldwide, it is imperative for conservation planning that we understand how large carnivores interact with their prey and competitors. Camera trapping offers a promising avenue to address this issue. We investigated temporal overlap between male and female leopards, their known and putative prey as well as their competitor, the spotted hyenas, in the Udzungwa Mountains of Tanzania. Data consisted of 4297 independent events from a 30 min interval criterion from 164 camera trap sites we sampled. Leopards were captured by camera traps throughout the day, with male and female leopards showing significantly different activity patterns (P < 0.001) indicating sexual segregation in activity patterns, with male leopards being more nocturnal than female leopards. Leopards had significantly different activity patterns from that of the majority of their prey, with yellow baboons, that displayed peak activity during midday, that had the least overlap. Moreover, both male and female leopards had significantly different activity patterns from that of spotted hyenas (P = <0.001), with female leopards appearing to be inactive during hours with peak hyena activity. We conclude that systematic camera trapping is a useful tool to study activity patterns and temporal niche interactions between sympatric carnivores and, to a lesser extent, their prey.

Spatio-temporal partitioning and coexistence between leopard (Panthera pardus fusca) and Asiatic lion (Panthera leo persica) in Gir protected area, Gujarat, India.

Time and space are essential niche dimensions along which species tend to coexist. We assessed spatiotemporal resource partitioning between leopards and lions and hypothesized the differential use of spatiotemporal resources by leopards with respect to lions. We used a systematic camera trap survey to collect the data at 50 sites. The data were analyzed using overlap indices, and non-parametric test statistics to assess the spatiotemporal associations. Leopard and lion were crepuscular and nocturnal in their activity pattern. They did not segregate temporally and showed substantially high overlap and strong temporal association. Leopard segregates with lion spatially by overlapping less and showing no association in space use at specific camera trap sites. Leopards showed preference for dense habitats, while the lion preferred both dense and open habitats. Leopard showed moderate-overlap and positive association with key prey species, i.e., chital and sambar. Lion, however showed low site-specific overlap and negative association with its crucial prey species, i.e., sambar and wild pig. We conclude that site-specific spatial partitioning along with differential affinities for habitat is helping leopards to partition their spatio-temporal resources with lions and hence facilitate coexistence of leopards with lions in Gir forest.

Local climate determines vulnerability to camouflage mismatch in snowshoe hares

AbstractAimPhenological mismatches, when life‐events become mistimed with optimal environmental conditions, have become increasingly common under climate change. Population‐level susceptibility to mismatches depends on how phenology and phenotypic plasticity vary across a species’ distributional range. Here, we quantify the environmental drivers of colour moult phenology, phenotypic plasticity, and the extent of phenological mismatch in seasonal camouflage to assess vulnerability to mismatch in a common North American mammal.LocationNorth America.Time period2010–2017.Major taxa studiedSnowshoe hare (Lepus americanus).MethodsWe used > 5,500 by‐catch photographs of snowshoe hares from 448 remote camera trap sites at three independent study areas. To quantify moult phenology and phenotypic plasticity, we used multinomial logistic regression models that incorporated geospatial and high‐resolution climate data. We estimated occurrence of camouflage mismatch between hares’ coat colour and the presence and absence of snow over 7 years of monitoring.ResultsSpatial and temporal variation in moult phenology depended on local climate conditions more so than on latitude. First, hares in colder, snowier areas moulted earlier in the fall and later in the spring. Next, hares exhibited phenotypic plasticity in moult phenology in response to annual variation in temperature and snow duration, especially in the spring. Finally, the occurrence of camouflage mismatch varied in space and time; white hares on dark, snowless background occurred primarily during low‐snow years in regions characterized by shallow, short‐lasting snowpack.Main conclusionsLong‐term climate and annual variation in snow and temperature determine coat colour moult phenology in snowshoe hares. In most areas, climate change leads to shorter snow seasons, but the occurrence of camouflage mismatch varies across the species’ range. Our results underscore the population‐specific susceptibility to climate change‐induced stressors and the necessity to understand this variation to prioritize the populations most vulnerable under global environmental change.

Camera trap survey of mammals in Cleopatra’s Needle Critical Habitat in Puerto Princesa City, Palawan, Philippines

A camera trap survey was conducted in the recently protected Cleopatra’s Needle Critical Habitat (CNCH) in Puerto Princesa City, Palawan, Philippines from February to May 2015 at 39 camera trap sites. A bait of common pig’s blood was used at 36 sites, while the three remaining sites were surveyed without a bait and monitored a stream with a latrine site or mud bath with tracks. Seven native species were detected and three of these species were endemic to the island province. Species included: Common Palm Civet Paradoxurus philippinensis, Palawan Porcupine Hystrix pumila, Collared Mongoose Urva semitorquata, Palawan Stink Badger Mydaus marchei, Palawan Leopard Cat Prionailurus bengalensis heaneyi, Asian Small-clawed Otter Aonyx cinereus, and Malay Civet Viverra tangalunga. Analysis of the activity patterns of the three most commonly captured species revealed predominantly nocturnal activity for the Common Palm Civet, Palawan Porcupine, and Palawan Stink Badger. The Philippine Palm Civet showed occasional diurnal activity. The seven photo-captured species appeared most common, or were at the least recorded, below 750m. Five species (the Philippine Palm Civet, Palawan Porcupine, Collared Mongoose, Palawan Stink Badger, and Palawan Leopard Cat) were also recorded above 1000m. The CNCH supports two threatened species, the Palawan Porcupine and the Asian Small-clawed Otter, which are listed as Vulnerable by the IUCN, and the Collared Mongoose is listed as Near Threatened. The Palawan Leopard Cat is considered Vulnerable within the Philippines, although it has yet to be assessed by the IUCN. This documentation highlights the biodiversity significance within the newly protected critical habitat and the need to support ongoing conservation efforts within the critical habitat. 

Spatial density estimates of Eurasian lynx (Lynx lynx) in the French Jura and Vosges Mountains.

Obtaining estimates of animal population density is a key step in providing sound conservation and management strategies for wildlife. For many large carnivores however, estimating density is difficult because these species are elusive and wide‐ranging. Here, we focus on providing the first density estimates of the Eurasian lynx (Lynx lynx) in the French Jura and Vosges mountains. We sampled a total of 413 camera trapping sites (with two cameras per site) between January 2011 and April 2016 in seven study areas across seven counties of the French Jura and Vosges mountains. We obtained 592 lynx detections over 19,035 trap days in the Jura mountains and 0 detection over 6,804 trap days in the Vosges mountains. Based on coat patterns, we identified a total number of 92 unique individuals from photographs, including 16 females, 13 males, and 63 individuals of unknown sex. Using spatial capture–recapture (SCR) models, we estimated abundance in the study areas between 5 (SE = 0.1) and 29 (0.2) lynx and density between 0.24 (SE = 0.02) and 0.91 (SE = 0.03) lynx per 100 km2. We also provide a comparison with nonspatial density estimates and discuss the observed discrepancies. Our study is yet another example of the advantage of combining SCR methods and noninvasive sampling techniques to estimate density for elusive and wide‐ranging species, like large carnivores. While the estimated densities in the French Jura mountains are comparable to other lynx populations in Europe, the fact that we detected no lynx in the Vosges mountains is alarming. Connectivity should be encouraged between the French Jura mountains, the Vosges mountains, and the Palatinate Forest in Germany where a reintroduction program is currently ongoing. Our density estimates will help in setting a baseline conservation status for the lynx population in France.

Wetlands are keystone habitats for jaguars in an intercontinental biodiversity hotspot.

Agricultural development was the major contributor to South America’s designation as the continent with the highest rates of forest loss from 2000–2012. As the apex predator in the Neotropics, jaguars (Panthera onca) are dependent on forest cover but the species’ response to habitat fragmentation in heterogeneous agricultural landscapes has not been a subject of extensive research. We used occupancy as a measure of jaguar habitat use in Colombia’s middle Magdalena River valley which, as part of the intercontinental Tumbes-Chocó-Magdalena biodiversity hotspot, is exceedingly fragmented by expanding cattle pastures and oil palm plantations. We used single-season occupancy models to analyze 9 months of data (2015–2016) from 70 camera trap sites. Given the middle Magdalena’s status as a “jaguar corridor” and our possible violation of the occupancy models’ demographic closure assumption, we interpreted our results as “probability of habitat use (Ψ)” by jaguars. We measured the associations between jaguar presence and coverage of forest, oil palm, and wetlands in radii buffers of 1, 3, and 5 km around each camera trap. Our camera traps recorded 77 jaguar detections at 25 of the camera trap sites (36%) during 15,305 trap nights. The probability of detecting jaguars, given their presence at a site, was 0.28 (0.03 SE). In the top-ranked model, jaguar habitat use was positively influenced by wetland coverage (β = 7.16, 3.20 SE) and negatively influenced by cattle pastures (β = -1.40, 0.63 SE), both in the 3 km buffers. We conclude that wetlands may serve as keystone habitats for jaguars in landscapes fragmented by cattle ranches and oil palm plantations. Greater focus on wetland preservation could facilitate jaguar persistence in one of the most important yet vulnerable areas of their distribution.

Habitat and introduced predators influence the occupancy of small threatened macropods in subtropical Australia.

Australia has had the highest rate of mammal extinctions in the past two centuries when compared to other continents. Frequently cited threats include habitat loss and fragmentation, changed fire regimes and the impact of introduced predators, namely the red fox (Vulpes vulpes) and the feral cat (Felis catus). Recent studies suggest that Australia's top predator, the dingo (Canis dingo), may have a suppressive effect on fox populations but not on cat populations. The landscape of fear hypothesis proposes that habitat used by prey species comprises high to low risk patches for foraging as determined by the presence and ubiquity of predators within the ecosystem. This results in a landscape of risky versus safe areas for prey species. We investigated the influence of habitat and its interaction with predatory mammals on the occupancy of medium‐sized mammals with a focus on threatened macropodid marsupials (the long‐nosed potoroo [Potorous tridactylous] and red‐legged pademelon [Thylogale stigmatica]). We assumed that differential use of habitats would reflect trade‐offs between food and safety. We predicted that medium‐sized mammals would prefer habitats for foraging that reduce the risk of predation but that predators would have a positive relationship with medium‐sized mammals. We variously used data from 298 camera trap sites across nine conservation reserves in subtropical Australia. Both dingoes and feral cats were broadly distributed, whilst the red fox was rare. Long‐nosed potoroos had a strong positive association with dense ground cover, consistent with using habitat complexity to escape predation. Red‐legged pademelons showed a preference for open ground cover, consistent with a reliance on rapid bounding to escape predation. Dingoes preferred areas of open ground cover whereas feral cats showed no specific habitat preference. Dingoes were positively associated with long‐nosed potoroos whilst feral cats were positively associated with red‐legged pademelons. Our study highlights the importance of habitat structure to these threatened mammals and also the need for more detailed study of their interactions with their predators.

Using camera traps to study the elusive European Wildcat Felis silvestris silvestris Schreber, 1777 (Carnivora: Felidae) in central Germany: what makes a good camera trapping site?

Camera traping is a widely used method to study the abundance and population density of elusive terrestrial animals. To make full use of this method, it is necessary to obtain high photographic capture rates of the target species. We examine what characteristics of camera trapping sites are associated with high photographic capture rates of European Wildcat Felis silvestris silvestris. We measured Wildcat capture rates across 25 camera trapping sites located in a 20km² study area within an unprotected low mountain range forest in central Germany. We measured the distance of each trapping site to the forest boundary, to the next watercourse, and to the next human settlement, and broadly defined the type of forest structure the site was located in. None of these site characteristics, however, predicted wildcat photographic capture success. We also examined the degree of human disturbance at the site, measured as the photographic capture rate of humans (including vehicles). Wildcats were detected at similar rates on dirt or gravel roads (heavily used by humans) as on soft-surfaced paths or logging trails (less frequently used by humans), and the degree of human disturbance across sites did not affect wildcat capture success. We, therefore, suggest that trail features such as course, curvature and width, or vegetation density along the trail are more important determinants of Wildcat capture success than habitat characteristics. We conclude that for European Wildcats, as for many larger felids, forest roads provide suitable camera trapping sites and that Wildcats are fairly tolerant towards human traffic on these roads.

Resource limitations and competitive interactions affect carnivore community composition at different ecological scales in a temperate island system

AbstractSelective pressures (i.e. resource limitation and competitive interaction) that drive the composition of ecological communities vary, and often operate on different ecological scales (ecological variables across varying spatial scales) than observed patterns. We studied the drivers of distribution and abundance of the American marten (Martes americana) and the carnivore community at three ecological scales on a Great Lakes island archipelago using camera traps. We found different drivers appeared important at each ecological scale and studying any of the three scales alone would give a biased understanding of the process driving the system. Island biogeography (resource limitation) was most important for carnivore richness, with higher richness on larger islands and lower richness as distance from the mainland increased. Marten presence on individual islands appeared to be driven by island size (resource limitation) and human avoidance (competitive interaction). Marten abundance at camera trap sites was driven by the cascading effect of coyotes (Canis latrans) on fishers (Pekania pennanti) (competitive interaction). Incorporating three ecological scales gave novel insights into the varying effects of resource limitation and competitive interaction processes. Our data suggests that ecological communities are structured through multiple competing ecological forces, and effective management and conservation relies on our ability to understand ecological forces operating at multiple ecological scales.

Coexistence of two sympatric flagship carnivores in the human-dominated forest landscapes of Northeast Asia

Understanding how large carnivore guilds survive in human-dominated landscapes is key to inform strategies for their conservation in the face of global carnivore declines. Amur tigers and leopards are recovering across the China-Russia border. However, knowledge is limited about competitive interactions between two large cats in Northeast Asia. To assess the spatial, temporal and combined spatiotemporal behavioral mechanisms potentially allow co-occurrence between tigers and leopards in a human-dominated forest landscape. Based on a large-scale camera-trapping data set in Northeast China, we used three different approaches for quantifying spatiotemporal associations: one spatial method (two-species occupancy model), one strictly temporal method (activity pattern overlap), and one spatiotemporal method based on multi-response permutation procedures at shared camera trap sites. Spatially, leopards showed no avoidance of the areas highly used by dominant tigers, but their diurnal activity pattern was significantly different from that of tigers. Spatiotemporal overlap analysis showed fine-scale behavioral avoidance when both co-occurred at camera locations, which further facilitates sympatry. Tigers spatially overlapped with humans, but they were less active during the day when human activities were more frequent. In areas with high cattle density, low occurrence of tigers and leopards may reflect the absence of sika deer, an important prey item for both species. This study provides the first empirical evidence that tigers do not limit leopard distributions, at least in our study area in Northeast Asia. Our results highlighted temporal segregation, not large-scaled spatial avoidance, as a key mechanism promoting coexistence of two large carnivores. Understanding these fine- spatial scale (i.e., camera locations) interactions between sympatric carnivores can help devise management strategies for predator guilds in human-dominated landscapes, currently a major global challenge.

Camera Trapping: A Tool to Study Hornbills?

Of the 57 species of hornbills in the world, 25 species are recorded in Africa, 32 species are recorded in Asia but only eight occur in Borneo. However, due to logging, hunting and forest fragmentation, the Bornean lowland forest often does not host all the species at once. The study of using remotely triggered infrared cameras in avifauna research is commonly used for medium to large terrestrial mammals, and birds, such as pheasants. Documentation of rare and new species presence records, behavioural studies, and activity patterns could also be included in the application of camera trapping in the study of birds. From the 304 camera trapping sites distributed throughout Sarawak, two species of hornbills were photographed during the study period: the White-Crowned Hornbill Berenicornis comatus and Asian Black Hornbill Anthracoceros malayanus. These images represent approximately 0.01% (34 out of 29,618 images) of the overall independent photos from a total effort of 29,470 camera trapping nights. Although data are insufficient to support the activity overlap between these two species, some baseline information on the behaviour of hornbills has been observed.

Detection of Endangered American Martens (Martes americana) in Apostle Islands National Lakeshore, Wisconsin

American martens (Martes americana) warrant concern in Wisconsin, U.S.A., for multiple reasons, including being the state's only endangered mammal and a clan animal of the Ojibwe tribes. American martens were once present throughout much of the state but were extirpated in the early 20th century through habitat loss and unregulated trapping. In the 1950s two reintroductions of martens to Stockton Island of the Apostle Islands archipelago were considered failures, with the last confirmed sighting in the archipelago in 1969. In the decades since the Stockton Island reintroduction efforts, anecdotal reports of martens have surfaced throughout the archipelago. In 2014–2016 we deployed 91 camera traps on 13 of the 21 Apostle Islands to survey the archipelago's extant carnivore species. We detected American martens at 28 of 87 functioning camera trap sites on 5 of 13 monitored islands and documented the existence of American martens in APIS in Wisconsin for the first time in over 50 y. We suggest continued research to evaluate the status of the APIS population and its potential origins to guide future conservation efforts.

Assessing the conservation value of secondary savanna for large mammals in the Brazilian Cerrado

Debate about the conservation value of secondary habitats has tended to focus on tropical forests, increasingly recognizing the role of secondary forests for biodiversity conservation. However, there remains a lack of information about the conservation value of secondary savannas. Here, we conducted a camera trap survey to assess the effect of secondary vegetation on large mammals in a Brazilian Cerrado protected area, using a single-season occupancy framework to investigate the response of individual species (species-level models) and of all species combined (community-level models). In addition, we investigated the cost effectiveness of different sampling designs to monitor globally threatened species in the study area. At the community level, savanna that regenerated from eucalyptus plantation had similar occupancy estimate as old growth areas. At the species level, none of the ten species individually assessed seemed to respond to succession stage, with greater support for the effect of other covariates on occupancy, such as distance from water and vegetation physiognomy. These results demonstrate that secondary vegetation does not appear to negatively impact large mammals in the study area and suggest that, given a favorable context, Cerrado mammals can recolonize and use secondary savannas that regenerated from clearcut. However, our study area should be considered a best-case scenario, as it retained key ecological attributes of high-value secondary habitats. Our simulations showed that a sampling design with 60 camera trap sites surveyed during nine occasions is appropriate to monitor most globally threatened species in the study area, and could be a useful starting point for new monitoring initiatives in other Cerrado areas.

Revealing kleptoparasitic and predatory tendencies in an African mammal community using camera traps: a comparison of spatiotemporal approaches

Camera trap data are increasingly being used to characterise relationships between the spatiotemporal activity patterns of sympatric mammal species, often with a view to inferring inter‐specific interactions. In this context, we attempted to characterise the kleptoparasitic and predatory tendencies of spotted hyaenasCrocuta crocutaand lionsPanthera leofrom photographic data collected across 54 camera trap stations and two dry seasons in Tanzania's Ruaha National Park. We applied four different methods of quantifying spatiotemporal associations, including one strictly temporal approach (activity pattern overlap), one strictly spatial approach (co‐occupancy modelling), and two spatiotemporal approaches (co‐detection modelling and temporal spacing at shared camera trap sites). We expected a kleptoparasitic relationship between spotted hyaenas and lions to result in a positive spatiotemporal association, and further hypothesised that the association between lions and their favourite prey in Ruaha, the giraffeGiraffa camelopardalisand the zebraEquus quagga, would be stronger than those observed with non‐preferred prey species (the impalaAepyceros melampusand the dikdikMadoqua kirkii). Only approaches incorporating both the temporal and spatial components of camera trap data resulted in significant associative patterns. The latter were particularly sensitive to the temporal resolution chosen to define species detections (i.e. occasion length), and only revealed a significant positive association between lion and spotted hyaena detections, as well as a tendency for both species to follow each other at camera trap sites, during the dry season of 2013, but not that of 2014. In both seasons, observed spatiotemporal associations between lions and each of the four herbivore species considered provided no convincing or consistent indications of any predatory preferences. Our study suggests that, when making inferences on inter‐specific interactions from camera trap data, due regards should be given to the potential behavioural and methodological processes underlying observed spatiotemporal patterns.

A two‐species occupancy model accommodating simultaneous spatial and interspecific dependence

Occupancy models are popular for estimating the probability a site is occupied by a species of interest when detection is imperfect. Occupancy models have been extended to account for interacting species and spatial dependence but cannot presently allow both factors to act simultaneously. We propose a two-species occupancy model that accommodates both interspecific and spatial dependence. We use a point-referenced multivariate hierarchical spatial model to account for both spatial and interspecific dependence. We model spatial random effects with predictive process models and use probit regression to improve efficiency of posterior sampling. We model occupancy probabilities of red fox (Vulpes vulpes) and coyote (Canis latrans) with camera trap data collected from six mid-Atlantic states in the eastern United States. We fit four models comprising a fully factorial combination of spatial and interspecific dependence to two-thirds of camera trapping sites and validated models with the remaining data. Red fox and coyotes each exhibited spatial dependence at distances > 0.8 and 0.4 km, respectively, and exhibited geographic variation in interspecific dependence. Consequently, predictions from the model assuming simultaneous spatial and interspecific dependence best matched test data observations. This application highlights the utility of simultaneously accounting for spatial and interspecific dependence.

An oasis in the desert: The potential of water sources as camera trap sites in arid environments for surveying a carnivore guild

Discussions regarding the importance of accounting for detection probability have long been present in ecological literature. Various studies have demonstrated the influence of survey design on detection probabilities, and whilst the placement of camera traps along roads is a commonly used survey design, it has shown to be biased towards certain species. In arid environments, water sources have the potential to be efficient sites for camera trap placement. We compared the influence of a water source camera trap survey design on the detection probabilities of a guild of seven carnivore species, in comparison detection probabilities from camera traps along roads, on arid, commercial farmland in southern Namibia. Results showed detection probabilities for all species to be higher at water, with the water source design producing shorter latencies of detections and higher naive occupancy estimates for most species. However, for species with unique markings, the water source design produced lower proportions of images suitable for individual identification. As detection probabilities of all species were influenced in a positive manner, we suggest placing camera traps at water sources in arid environments to be an effective survey design. However, for surveys requiring individual identification, placing camera traps along roads may be more suitable.

Spatially explicit capture–recapture analysis of bobcat (Lynx rufus) density: implications for mesocarnivore monitoring

Context Accurate density estimation is crucial for conservation and management of elusive species. Camera-trapping may provide an efficient method for density estimation, particularly when analysed with recently developed spatially explicit capture–recapture (SECR) models. Although camera-traps are employed extensively to estimate large carnivore density, their use for smaller carnivores has been limited. Moreover, while camera-trapping studies are typically conducted at local scales, the utility of analysing larger-scale patterns by combining multiple camera studies remains poorly known. Aims The goal of the present study was to develop a better understanding of the utility of SECR models and camera-trapping for the estimation of density of small carnivores at local and regional scales. Methods Based on data collected from camera-traps, we used SECR to examine density of bobcats (Lynx rufus) at four study sites in north-central Texas. We then combined our density estimates with previous estimates (from multiple methodologies) across the bobcat’s geographic range, and used linear regression to examine drivers of range-wide density patterns. Key results Bobcat densities averaged 13.2 per 100 km2 across all four study sites, and were lowest at the site in the most heavily modified landscape. Bobcat capture probability was positively related to forest cover around camera-trap sites. At the range-wide scale, 53% of the variation in density was explained by just two factors: temperature and longitude. Conclusions Our results demonstrate the utility of camera-traps, combined with SECR, to generate precise density estimates for mesocarnivores, and reveal the negative effects of landscape disturbance on bobcat populations. The associations revealed in our range-wide analysis, despite variability in techniques used to estimate density, demonstrate how a combination of multiple density estimates for a species can be used for large-scale inference. However, improvement in our understanding of biogeographic density patterns for mesocarnivores could be obtained from a greater number of camera-based density estimates across the range of a species, combined with meta-analytic techniques. Implications Camera-trapping and SECR should be more widely applied to generate local density estimates for many small and medium-sized carnivores, where at least a portion of the individuals are identifiable. If such estimates are more widely obtained, meta-analytic techniques could be used to test biogeographic predictions or for large-scale monitoring efforts.