Camera Traps Research Articles

A multivariate approach to assessing landscape structure effects on wildlife crossing structure use

BackgroundComplexity in landscape structure is often assessed using individual metrics related to ecological processes. However, this rarely incorporates important relationships among metrics and may miss landscape structure effects. Multivariate statistics provide techniques for assessing overall landscape structure effects. We assessed how multivariate statistics could be used to connect landscape structure with an ecological process [bobcat (Lynx rufus) wildlife crossing structure (WCS) use]. We tested how landscape structure at WCS sites compared to the surrounding landscape and how structure affected detections at WCS sites. Our study was conducted in Cameron County, Texas, USA where WCSs are in various stages of construction and monitoring. We used a classified land use/land cover map and aerial LiDAR to calculate configuration and density metrics at WCS and random sites. We created indices for configuration and density using principal components analysis to assess landscape structure effects on camera trap detections at WCSs.ResultsLandscape structure at WCSs did not differ from random locations. Wildlife crossing structure use increased with greater woody cover and decreased with increasing vegetation density. Our indices allowed identification of differences in how configuration and density impacted WCS use. Ordination methods helped identify individual contributions of landscape metrics to the overall landscape structure effect.ConclusionsWildlife crossing structures are permanent fixtures on landscapes, so selecting appropriate locations using broad-scale landscape structure likely increases target species use. Using indices of landscape structure provides planners with a more holistic approach to WCS placement and provides a more comprehensive picture of landscape pattern and process relationships.

Scent lures and baits at camera traps improve time to first detection and detection probability of two typically elusive species of weasel

There is a growing body of evidence that weasel species are in decline globally. More data on their ecology and distribution are needed to plan and justify any conservation management actions. Camera trapping can be an effective survey method for many species; however, the small size and quick movements of weasels present challenges in detection and little consensus exists on practices for attracting them to improve detection. This study tested different combinations of meat baits and scent and audio lures to assess the most effective methods. Camera traps were set up in clusters of three at 42 sites to test the effectiveness of these combinations, accounting for season, in terms of the time to first detection (TFD), detection probability using occupancy models, and the number and clarity of weasel photos. We also repeated TFD and detection probability analyses for setups that were ≥ 20 m apart in case of overlap of effects. The average TFD across all sites was 43 days. Fall typically had the shortest TFD with beaver bait in fall achieving the best results. After accounting for occupancy, predicted detection probability across a 60-day survey was highest in fall with the best combination being salmon lure and beaver bait. The treatment type did not impact the average number of photos captured, but the clarity of photos was significantly positively related to use of bait and lure, type of lure, and specific combinations of bait and lure.

Generating wildlife density data across Europe in the framework of the European Observatory of Wildlife (EOW)

Abstract The European Observatory of Wildlife EOW, as part of the ENETWILD project, represents a collaborative network that has been operating since 2021 to develop and implement standardized protocols to obtain harmonized data on distribution and density of target mammal species. In so doing, the EOW aims at contributing to improving the quality of data that are available for wildlife management and risk assessment on a European scale. This report describes the activities carried out during the 2023 EOW campaign, which was joined by a total of 30 organizations who committed to collect data in 44 sites across 22 different countries. We present data on the distribution and density of three species – wild boar (Sus scrofa), European roe deer (Capreolus capreolus), and red fox (Vulpes vulpes) – obtained by implementing a camera trapping protocol and by fitting the random encounter model (REM) for density estimation. Camera‐trap images were processed using the Agouti platform and some of its tools specifically designed for the management of camera trapping projects. This includes the use of photogrammetry to obtain parameters for the REM directly from the sequences of images. A total of 24 EOW sites were monitored in past years as well, providing multiannual density estimates and population trends and highlighting an improvement in the precision of the estimates, related to the improved study design and protocol implementation. We also describe the activities of the 2024 campaign, carried out as part of ENETWILD 2.0, where big efforts were made to expand the network, focusing on sites at risk of African Swine Fever, with wild boar/pig interactions and containing wetlands, as potential hubs for Avian Influenza. This effort resulted in the engagement of 40 participants monitoring 64 study sites (27 countries), including 28 study sites located either in infected areas or < 100km from the ASF frontline, and 25 sites with wetland habitats. Furthermore, in at least 20 sites pig farming is practised either intensively, extensively or as backyard farming. Finally, synergies were established with other international initiatives related to wildlife monitoring and disease prevention, with the aim of sharing experiences and sustaining a transnational data collection and harmonization.

Effects of Grazing by Native and Non-Native Terrestrial Vertebrates on the Growth of Tecticornia arbuscula in Australian Temperate Saltmarshes

The effects of grazing and browsing by terrestrial vertebrates are poorly understood for southern hemisphere saltmarshes, many of which are recovering from stock grazing. We investigated whether the native late-successional shrub, Tecticornia arbuscula, regenerating several years after the cessation of stock grazing, was grazed by wild herbivorous mammals to the degree of impeding recovery. We measured T. arbuscula growth parameters in exclosures and adjacent controls for two years and used camera trapping of animals across four consecutive austral seasons to indicate grazing pressure. Height growth was more affected by exclosure from grazing than lateral change. Notably, grazing did not prevent the recovery of the shrubs from stock grazing at either site, suggesting that the growth rate of T. arbuscula relative to total grazing pressure is at sustainable levels and these shrubs are in a trajectory of recovery, with the smaller plants growing the fastest. Also, we found little difference between our two sites in grazing impact, despite one site having twice the number of animals, largely native macropods, as the other site, which was dominated by introduced lagomorphs (rabbits and hares). These findings further the knowledge of native and non-native terrestrial vertebrates in austral saltmarsh ecology and conservation.

Human-Wildlife Conflict in Bardia-Banke Complex: Patterns of Human Fatalities and Injuries Caused by Large Mammals.

Human fatalities and injury from wildlife attacks often result in a negative attitude toward conservation. This research was undertaken to investigate the patterns and conflict-causing factors of human killing and injury by large mammals, especially by Asian elephant (Elephas maximus), common leopard (Panthera pardus), and Bengal tiger (Panthera tigris tigris) in the Bardia-Banke Complex of western Nepal. We collected human death and injury records caused by wildlife in the Bardia-Banke Complex between 2019 and 2023, based on relief applications submitted by the victim's family. Additionally, camera trap monitoring was conducted following incidents of human-tiger and human-leopard conflicts. A total of 76 incidents involving human casualties and injuries were considered for analysis. Incidents of livestock depredation, crop raiding, and property damage were excluded from the analysis. Most of the attacks on humans were caused by tigers (75%), followed by elephants (16%) and leopards (9%). Almost all incidents occurred in daytime (97%). The highest number of conflicts were recorded in 2021, with 20 incidents. Most of the cases (84%) occurred within 1 km of forest edge. Khata corridor and the western side of the Bardia National Park, i.e., Karnali River corridor, were identified as high-conflict areas. The primary causes of the conflict manifested in cattle grazing (28%), grass cutting (28%), firewood collection (11%), fishing (8%), vegetable collection (5%), sand collection (4%), during rescuing friends (3%), grazing captive elephants (3%), highway rides (3%), sleeping in Chaupadi Goth (3%), walking nearby forest areas (3%), playing nearby forest areas (1%), while feeding pig (1%), and working in agricultural lands (1%). To promote human-wildlife coexistence, community-based patrols (33%), habitat restoration (26%), electric fencing (26%), and insurance (7%) were identified as the preferred strategies. Therefore, we recommend that stakeholders and concerned bodies increase awareness among local community about the use of forest resources, wildlife behavior, and human-wildlife conflict mitigation strategies.

External and internal driving forces of community and functional group stability in the forest mammal community

Conserving mammal community stability in forest ecosystems is an urgent challenge in the face of global biodiversity threats and complex trophic interaction. However, understanding of the stability of mammal communities and targeted functional groups is still limited, hindering adaptive strategy development. We collected 210 120 camera trap photos across 5897 km 2 within the Amur tiger ( Panthera tigris altaica ) range in China’s natural forests. We decomposed stability into compensatory effects, statistical-averaging effects and population stability. Using structural equation modelling, we explored the impact of external factors, species diversity and vertical effects on the stability of the community and of four functional groups. As external factors, primary productivity increased the stability of top predators, while precipitation had inconsistent effects. Horizontal diversity (richness and evenness) positively impacted community stability. However, the vertical structure of the community, including trophic-level richness and functional groups’ compensatory dynamics, were the largest drivers for maintaining community stability. Horizontal diversity within functional groups and the diversity or biomass of their food resources/consumers both influenced the stability of functional groups. Our results recognize the importance of conserving and even re-establishing vertical trophic structures in forest communities. Acknowledging multiple levels of stability, from functional groups to communities, is an indispensable step for effective conservation strategies.

Ecological Adjustments and Behavioural Patterns of the European Badger in North-Western Italy

The European badger is a highly adaptable species, inhabiting a range of environments across Europe, from woodlands to urban areas, with its behaviour influenced by environmental conditions and human activities. This study examines the badger feeding habits, patterns of diel activity, and sett site choice in north-western Italy, assessing how landscape composition affects these behaviours. We conducted our research across seven study areas in northern Italy from December 2020 to November 2022, utilising camera trapping, faeces analysis, and sett surveys. Our findings revealed significant dietary variation, with earthworms being the primary food source in natural landscapes, while fleshy fruits being consumed especially in mixed and heavily modified landscapes, up to constitute the staple of the diet in one agricultural area. Badgers were found to be nocturnal, primarily active between sunset and sunrise. Setts varied considerably in structure and location, with a preference for natural grounds over human-made structures; key factors influencing sett site choice included slope, exposure, and vegetation cover. This study underscores the European badger’s remarkable adaptability, illustrating how its diet, activity patterns, and sett site preferences are shaped by a complex interplay of factors, allowing the species to thrive in both pristine and modified environments across northern Italy.

A chucao tapaculo, Scelorchilus rubecula (Kittlitz, 1830), plucking hair from a southern pudu, Pudu puda (Molina, 1782), in the Chilean temperate forest

AbstractAlthough the incorporation of mammalian hair in nest construction for thermal insulation has been extensively documented among birds, the kleptotrichy—where birds pluck hair directly from living mammals—remains a relatively underreported behaviour in the scientific literature. Our camera trap monitoring effort in Pumalín Douglas Tompkins National Park, Chile, captured a chucao tapaculo (Scelorchilus rubecula) plucking hair from a southern pudu (Pudu puda). The observed behaviour suggests an adaptation for obtaining nest material, particularly in high‐latitude regions like our study area. The pudu's minimal reaction suggests that the hair removal was not perceived as uncomfortable, potentially because the hair was already being shed. This could also be interpreted as a case of ectoparasite removal or other mutualistic interactions. Further research is needed to determine the use of pudu hair as nest construction material and to explain the ecological implications of this behaviour. Our findings highlight the value of camera trap monitoring in expanding the knowledge of species interactions and providing insights about wildlife behaviours.

The moon's influence on the activity of tropical forest mammals.

Changes in lunar illumination alter the balance of risks and opportunities for animals, influencing activity patterns and species interactions. We examined if and how terrestrial mammals respond to the lunar cycle in some of the darkest places: the floors of tropical forests. We analysed long-term camera trapping data on 86 mammal species from 17 protected forests on three continents. Conservative categorization of activity during the night revealed pronounced avoidance of moonlight (lunar phobia) in 12 species, compared with pronounced attraction to moonlight (lunar philia) in only three species. However, half of all species in our study responded to lunar phases, either changing how nocturnal they were, altering their overall level of activity, or both. Avoidance of full moon was more common, exhibited by 30% of all species compared with 20% of species that exhibited attraction. Nocturnal species, especially rodents, were over-represented among species that avoided full moon. Artiodactyla were more prominent among species attracted to full moon. Our findings indicate that lunar phases influence animal behaviour even beneath the forest canopy. Such impacts may be exacerbated in degraded and fragmented forests. Our study offers a baseline representing relatively intact and well-protected contexts together with an intuitive approach for detecting activity shifts in response to environmental change.

Wild ungulates employ spatio-temporal niche partitioning to coexist with livestock in resource-limited Trans-Himalayan rangelands, India

Wild ungulates employ spatio-temporal niche partitioning to coexist with livestock in resource-limited Trans-Himalayan rangelands, India

Monitoring bird and mammal diversity using camera trapping in Jingwan-dong wetland

Monitoring bird and mammal diversity using camera trapping in Jingwan-dong wetland

Measuring the benefit of a defensive trait: Vigilance and survival probability.

Defensive traits are hypothesized to benefit prey by reducing predation risk from a focal predator but come at a cost to the fitness of the prey. Variation in the expression of defensive traits is seen among individuals within the same population, and in the same individual in response to changes in the environment (i.e., phenotypically plastic responses). It is the relative magnitude of the cost and benefit of the defensive trait that underlies the defensive trait expression and its consequences to the community. However, whereas the cost has received much attention in ecological research, the benefit is seldom examined. Even in a defensive trait as extensively studied as vigilance, there are few studies of the purported benefit of the behavior, namely that vigilance enhances survival. We examined whether prey vigilance increased survival and quantified that benefit in a natural system, with white-tailed deer (Odocoileus virginianus) experiencing unmanipulated levels of predation risk from Florida panther (Puma concolor coryi). Deer that spent more time vigilant (as measured by head position using camera trap data) had a higher probability of survival. Indeed, an individual deer that was vigilant 75% of the time was more than three times as likely to be killed by panthers over the course of a year than a deer that was vigilant 95% of the time. Our results therefore show that within-population variation in the expression of a defensive trait has profound consequences for the benefit it confers. Our results provide empirical evidence supporting a long-held but seldom-tested hypothesis, that vigilance is a behavior that reduces the probability of predation and quantifies the benefit of this defensive trait. Our work furthers an understanding of the net effects of a trait on prey fitness and predator-prey interactions, within-population variation in traits, and predation risk effects.

Occurrence and distribution of Indian Pangolin Manis crassicaudata (Mammalia: Pholidota: Manidae) in the protected area network of Jammu Shiwaliks, India

The Indian Pangolin Manis crassicaudata, a rare and elusive species distributed across the Indian sub-continent, remains poorly understood due to its nocturnal and solitary behaviour, resulting in a lack of understanding about its ecology. This study presents the distribution of the animal in protected areas in Jammu Shiwaliks, India using the data obtained from camera trap images. Eighteen mammals including the Indian Pangolin were recorded from 131 camera trap locations during 3,144 trap nights in a cumulative protected area of 127km2 in an elevational range of 358–880 m. Given its ecological significance, more rigorous surveys need to be conducted to gain a comprehensive understanding of the distribution, ecology, and habitat utilization of Indian Pangolin across the Jammu Shiwaliks.

Camera Traps Reveal Variation in Diel Activity Patterns among Different Sex-Age Classes in Brown Bears in Hokkaido

Camera Traps Reveal Variation in Diel Activity Patterns among Different Sex-Age Classes in Brown Bears in Hokkaido

Anthropogenic landscape features affect the ground habitat use of Penelope superciliaris (Cracidae), a large seed disperser bird in southeastern Brazil

AbstractThe expansion of agriculture and forest plantations over tropical biomes has caused significant species loss, while others persist in remnant native areas and anthropogenic lands. Penelope superciliaris, a large seed disperser bird, inhabits human‐modified landscapes; however, its habitat use is poorly known. We investigated how native land covers, distance to water sources, and anthropogenic landscape features affect the species' ground habitat use in disturbed and undisturbed areas of three landscapes in Southeastern Brazil. We expected the species to use the ground more in native areas and near water sources because of the higher habitat quality. We collected presence‐absence data during two dry seasons at 205 sampling stations with camera traps. Using occupancy models, we calculated the cumulative AICc weights of covariates for occupancy (interpreted as probability of use, Ψ) and detection (interpreted as frequency of use, p) parameters. The proportion of managed forests negatively influenced the species' frequency of use. The probability of use was higher when camera trap stations were located on unpaved roads. Model averaged prediction showed that the species uses about 56% of the landscapes. Our results suggest that intensively managed forests are not favorable or attractive habitats for the species. Unpaved roads associated with native vegetation edges may provide valuable habitats for the species during the dry season, possibly associated with movement and resource tracking. These findings may help guide conservation strategies in such modified landscapes, with caution in considering unpaved roads as secure habitats until further data on population abundance are available.Abstract in Portuguese is available with online material.

Vertebrate seed predation can limit recruitment of later‐successional species in tropical forest restoration

AbstractThe effects of vertebrate seed predation on the regeneration of restored forests are not well understood because most past studies have focused on seed predation within the first few years after restoration and have measured seed removal without quantifying subsequent seedling establishment of seeds that avoid predation. Quantifying the establishment of seeds that escape predation in restored forests at later stages of regrowth is crucial for anticipating longer‐term recovery trajectories. Here, we evaluated the potential role of vertebrate seed predators in limiting recruitment of later‐successional tree species in nine forests actively restored ≥15 years prior and in four paired remnant forest fragments embedded in an agricultural landscape in southern Costa Rica. We conducted seed addition experiments with four tree species inside and outside vertebrate exclosures and used camera trapping to detect seed predators. To determine the fate of seeds that avoided predation, we also measured seedling establishment after 1 year, given that other mortality factors may compensate in the absence of vertebrate seed predation. We detected two species of birds and five species of granivorous mammals removing seeds. Seed tagging indicated that most removal resulted in predation. For three of the four tree species tested, vertebrate seed predation reduced seedling establishment. The magnitude of this effect depended on species' susceptibility to other causes of mortality during the seed‐to‐seedling transition. Our study demonstrates that vertebrate seed predators can substantially reduce later‐successional seedling recruitment in restored forests and should be considered alongside dispersal limitation and microsite conditions as factors slowing forest recovery.Abstract in Spanish is available with online material.

New range record for Campbell’s monkeys (<i>Cercopithecus campbelli</i>) in West Africa

The current distribution of Campbell’s monkeys Cercopithecus campbelli extends from southwestern Gambia to the western Ivory Coast. In Senegal, it has only been confirmed in the western part of the country. Here, we report for the first time its presence in southeastern Senegal. We obtained camera trap footage of a Campbell’s monkey individual in the Dindefelo Community Nature Reserve located in Kedougou region, 174 km away from its known distribution range. In the footage, a single Campbell’s monkey appears alongside a group of at least nine green monkeys Chlorocebus sabaeus. We discuss different hypotheses that could explain the presence of the Campbell’s monkey in Dindefelo, and conclude that this individual may be a single migrant.

Comparing the effectiveness of environmental DNA and camera traps for surveying American mink (Neogale vison) in northeastern Indiana.

While camera traps can effectively detect semi-aquatic mammal species, they are also often temporally and monetarily inefficient and have a difficult time detecting smaller bodied, elusive mammals. Recent studies have shown that extracting DNA from environmental samples can be a non-invasive, alternative method of detecting elusive species. Environmental DNA (eDNA) has not yet been used to survey American mink (Neogale vison), a cryptic and understudied North American mustelid. To help determine best survey practices for the species, we compared the effectiveness and efficiency of eDNA and camera traps in surveys for American mink. We used both methods to monitor the shoreline of seven bodies of water in northeastern Indiana from March to May 2021. We extracted DNA from filtered environmental water samples and used quantitative real-time PCR to determine the presence of mink at each site. We used Akaike's Information Criterion to rank probability of detection models with and without survey method as a covariate. We detected mink at four of the seven sites and seven of the 21 total survey weeks using camera traps (probability of detection (ρ) = 0.36). We detected mink at five sites and during five survey weeks using eDNA (ρ = 0.25). However, the highest probability of detection was obtained when both methods were combined, and data were pooled (ρ = 0.47). Survey method did not influence model fit, suggesting no difference in detectability between camera traps and eDNA. Environmental DNA was twice as expensive, but only required a little over half (58%) of the time when compared to camera trapping. We recommend ways in which an improved eDNA methodology may be more cost effective for future studies. For this study, a combination of both methods yielded the highest probability for detecting mink presence.

Relating Wildlife Camera Trap Data to Tick Abundance: Testing the Relationship in Different Habitats.

The increase in acarological risk of tick bites is significantly driven by profound changes in landscape, which alter the density and distribution of wildlife that support tick populations. As a result of habitat shifts and land abandonment, which create environments conducive to tick proliferation, the risk of disease transmission to humans and animals is increasing. In this context, it is important to explore tick ecology by applying a comprehensive methodology. In this study, we examined the relationship between wildlife temporal occupancy and tick abundance in two distinct regions: an alpine hunting district and a natural park in the Apennines. For each sampling point, we calculated wildlife temporal occupancy from camera trap pictures and estimated ticks' abundance from dragging transects in the area immediately surrounding camera traps. In modelling the relationship between those two variables, we included abiotic factors such as saturation deficit, normalized difference vegetation index, and altitude. Results show the importance of altitude and wildlife temporal occupancy (itself related to different habitat and land management characteristics) on the ecology of questing ticks. If employed in management decisions for natural environments, such information is useful to modulate the acarological risk and thus the risk of tick-borne pathogens' transmission.

Relative abundance of a mesocarnivore in a human-dominated, semi-arid rangeland in Namibia

Mesocarnivores fill important roles in ecological communities globally, but their distribution and abundance are often understudied. Many species have historically been regarded as vermin and subject to lethal control due to their role in livestock predation. Identifying the factors influencing mesocarnivore populations can help disentangle their relationship within ecological communities and inform conflict mitigation and conservation priorities. To help identify these factors, we used camera traps to study the community of medium and large mammals in four communal conservancies of northeastern Namibia covering the wet and dry seasons using 99 and 97 camera trap stations, respectively. We modelled black-backed jackal (Lupulella mesomelas) abundance using the robust Royle-Nichols model. Black-backed jackal were widespread, with a mean per site abundance of 2.01 (SD=0.66) in the wet season and 2.41 (SD=0.49) in the dry season. Black-backed jackal showed seasonally contrasting covariate associations, with lower abundance in areas with medium and large-sized wild prey during the wet season, and higher abundance in areas with more villages and close to African wild dog (Lycaon pictus) dens in the dry season. We identified localized hotspots of black-backed jackal abundance during the dry season, which may indicate that when resources are scarce, black-backed jackals rely on anthropogenic food sources despite an elevated risk for conflict, and on carcass remains from African wild dog kills. These findings highlight potential drivers of mesocarnivore abundance that would be obscured in a conventional occurrence modelling framework, and illustrate how local abundance may be influenced by seasonal variability, wild and anthropogenic food sources, and a likely facilitative relationship with a large carnivore. Further investigations in areas with more complex carnivore guilds and higher density of dominant predators are needed to understand black-backed jackal-African wild dog interactions and impacts on population dynamics.