Infrared-triggered Cameras Research Articles

AUTOMATIC VIDEO DETECTION FOR GOLDEN MONKEYS IN SHENNONGJIA NATIONAL PARK, CHINA

Abstract. Infrared-triggered cameras serve as essential tools for wildlife resource surveys, allowing camera traps to capture wildlife activity while minimizing the impact on the ecosystem. Traditional monitoring methods heavily rely on human resources for visual discrimination, which is inefficient and susceptible to environmental influences. Therefore, this paper focuses on Shennongjia National Park as a case study to address the limitations of traditional approaches. We constructed a Shennongjia wildlife object detection dataset using video data from the fixed-erected infrared cameras and proposed a supervised learning-based automatic monitoring method for golden monkeys, aiming to achieve intelligent target detection. With these processing results, we were able to capture golden monkeys' tracks and conduct statistical analysis of their life range and distribution characteristics. Through the integration of sensors and deep learning techniques, we developed a golden monkeys detection monitoring system to visualize the monitoring results and assess the spatial and temporal distribution characteristics of golden monkeys’ activities.

Assessing mammal fence crossing and local fence management in relation to classical swine fever spread in Japan.

Infectious diseases at the wildlife-livestock-human interface have become a crucial issue, and evidence-based measures are growing increasingly important. One countermeasure against animal diseases in wildlife is using fencing to contain and reduce disease spread and transmission rates between wild populations; however, quantitative assessments on fencing are rare. Moreover, existing research on fencing has highlighted knowledge gaps on the social and ecological aspects relevant to the use and design of fences. To control the spread of classical swine fever, fences were installed from the east to west in Gifu Prefecture, Japan, by March 2019, with the aim of restricting wild boar movement. To clarify the process of installation and maintenance of the fences, we conducted semi-structured interviews with prefectural government officers in Gifu Prefecture. Additionally, we installed infrared-triggered cameras at fence locations with and without gaps to evaluate the fence permeability of mammals. We used a generalized linear mixed model to evaluate the relationship between the presence of gaps and the relative abundance and permeability of each mammal. Our findings showed that the occurrence of gaps was inevitable during the installation and management of wide-area perimeter fence in Japan, partly because of social factors. For example, fences could not be installed on roads that were frequently used by residents and were not adequately maintained owing to budgetary reasons in some cases. Analysis of footage from the infrared-triggered cameras revealed that several mammal species crossed the fence at gaps and even had the ability to cross the gapless parts of the fences. Wild boars crossed through the gaps regularly. It is possible that Sika deer, Japanese serows, raccoons, Japanese badgers, raccoon dogs, Japanese macaques, and feral cats crossed through fence gaps because their relative abundance was high at gap locations. In contrast, Japanese hares slipped through the fence mesh rather than crossing through the gaps. In conclusion, we suggest that coordination and collaboration among related parties, a sufficient supply of fence materials, and securing a budget for fence maintenance are important for fence installation and maintenance. Furthermore, as fence gaps are inevitable, technical development of countermeasures for these gaps could be effective.

Home nocturnal infrared video to record non-rapid eye movement sleep parasomnias.

To assess the feasibility, the acceptability and the usefulness of home nocturnal infrared video in recording the frequency and the complexity of non-rapid eye movement sleep parasomnias in adults, and in monitoring the treatment response. Twenty adult patients (10 males, median age 27.5 years) with a diagnosis of non-rapid eye movement parasomnia were consecutively enrolled. They had a face-to-face interview, completed self-reported questionnaires to assess clinical characteristics and performed a video-polysomnography in the Sleep Unit. Patients were then monitored at home during at least five consecutive nights using infrared-triggered cameras. They completed a sleep diary and questionnaires to evaluate the number of parasomniac episodes at home and the acceptability of the home nocturnal infrared video recording. Behavioural analyses were performed on home nocturnal infrared video and video-polysomnography recordings. Eight patients treated by clonazepam underwent a second home nocturnal infrared video recording during five consecutive days. All patients had at least one parasomniac episode during the home nocturnal infrared video monitoring, compared with 75% during the video-polysomnography. A minimum of three consecutive nights with home nocturnal infrared video was required to record at least one parasomniac episode. Most patients underestimated the frequency of episodes on the sleep diary compared with home nocturnal infrared video. Episodes recorded at home were often more complex than those recorded during the video-polysomnography. The user-perceived acceptability of the home nocturnal infrared video assessment was excellent. The frequency and the complexity of the parasomniac episodes decreased with clonazepam. Home nocturnal infrared video has good feasibility and acceptability, and may improve the evaluation of the phenotype and severity of the non-rapid eye movement parasomnias and of the treatment response in an ecological setting.

Effects of vehicle-passing frequency on forest roads on the activity patterns of carnivores

In this study, we evaluated the effect and extent of linear human disturbance caused by vehicle traffic on forest roads on animal activity time. Our research focused on four sympatric carnivores (red fox, Vulpes vulpes; raccoon dog, Nyctereutes procyonoides; Japanese marten, Martes melampus; and Asiatic black bear, Ursus thibetanus) living in the forest region of northeastern Japan. From August to November 2019, we obtained data on the activity time for each species from nine infrared-triggered cameras installed along two types of unpaved forest roads with different vehicle frequencies (high or low) and subsequently assessed the effect of vehicle-passing frequencies on activity using kernel density estimation and chi-square test. Red foxes and raccoon dogs were nocturnal on all forest roads; however, their nighttime activities were significantly greater on the forest road with a high vehicle-passing frequency than on the road with a low vehicle-passing frequency. Japanese martens showed a nocturnal pattern on all forest roads, and there was no significant difference in the proportion of nighttime activities between the forest roads. Asiatic black bears were highly active during the daytime on forest roads with a low vehicle-passing frequency, but were highly nocturnal on forest roads with a high vehicle-passing frequency. Our results suggest that human disturbance influences the ratio of daytime to nighttime activity in carnivores; however, the extent and magnitude of this effect are limited. This finding indicates that the spatial scale of effects of human disturbance on the activity of each animal species should be assessed before habitat management programs are implemented.

Nest predation on an abundant generalist bird in tropical China

Nest predation is the main reason for breeding failure of small passerines. Theory states that predation in the incubation stage should be mostly due to predators finding poor-quality sites, whereas predation in the nestling stage may be driven by parental activity. Yet field evidence for this theory is mixed, and there are few studies from tropical Asia. Red-whiskered Bulbul (Pycnonotus jocosus; RWB) is an abundant generalist species in tropical Asia, often found in human-modified environments. Between 2012 and 2017 in the Xishuangbanna Tropical Botanical Garden, Yunnan, China, we monitored 775 RWB nests, including 287 nests with infrared-triggered cameras, 20 nests with digital video cameras, and 10 with temperature data loggers. The richness of nest predators was high, with at least 11 species, including mammalian, avian, reptilian, and invertebrate species; northern tree shrew (Tupaia belangeri) and Greater Coucal (Centropus sinensis) were the predator species most detected and identified. There was no significant difference in daily predation rate (DPR, as assessed by the Mayfield method) between incubation (DPR = 0.046, n = 682) and nestling (DPR = 0.049, n = 525) stages, even though parental visits in the nestling stage were almost 3 times the number in the incubation stage. Yet during the nestling period there was a strong positive relationship between the parental visitation on a particular day post-hatching (from day 1 to day 10; visitation measured with digital video cameras) and the nest predation rate of that day (measured on all nests). To determine the effect of nest sites on predation, we placed clay eggs in 127 previously used RWB nests. Sites that had been depredated at the incubation stage had marginally higher DPR (0.076, n = 43) when reused than sites that had been successful (DPR = 0.043, n = 50), although this difference was not significant when Bonferroni-corrected. This result thus provides weak evidence for an effect of nest site selection on nest predation. In total, this study emphasizes the strong forces of selection during the nesting period, particularly for birds in human-modified tropical habitats where the diversity of nest predators is high.

Predation Patterns on Artificial Nests of Ground Nesting Pheasants in the Montane Forest, Southwest China

Nest predation is a major cause leading to reproductive failure of many avian species. Identifying nest predators is crucial for understanding the ecological context of nest predation and habitat management. The mountains of Southwest China harbors numerous species in the Phasianidae family, many of them endemic or threatened, however, little is known on the nest predation pressure on these ground breeders. We placed 32 artificial nests (each containing two chicken eggs) in broadleaf montane forests with different vegetation structure, and monitored predators with infrared-triggered cameras. The artificial nests were resembling nests of Golden Pheasant Chrysolophus pictus, a representative of the threatened species inhabiting montane broadleaf forest. We analyzed how environmental factors impact survival of artificial nests using Cox proportional hazards regression. With a failure rate of 62.5%, we recorded 40 predations where eggs were preyed or moved away, 19 predation attempts where animals spotted and contacted with, but failed to prey on or move away the eggs, and 109 pass-by events. Corvids, especially Large-billed Crow Corvus macrorhynchos was the primary culprit, committing all but one predations on artificial nests. Other potential predators included Pere David's Rock Squirrel Sciurotamias davidianus, Eurasian Jay Garrulus glandarius, Red-billed Blue Magpie Urocissa erythrorhyncha, Chinese Porcupine Hystrix hodgsoni and muridaes. We found that understory cover and vertical openness were the determining factors on survival of artificial nests. Presence of understory cover and low vertical openness significantly increased survival time of artificial nests. We didn't detect significant effects from horizontal openness and distance to nearest patrol trail. Further studies with real nests are however required to examine these conclusions, and to explore reproduction strategies of ground nesting pheasants coping with threats from avian predators.

Artificial Intelligence's Role in Global Camera Trap Data Management and Analytics via Wildlife Insights

Camera traps have existed since the 1890s (Kucera and Barrett 2011), but they weren’t widely used until the introduction of commercial infrared-triggered cameras in the early 1990s (Meek et al. 2014). Since then, millions, perhaps billions of camera trap images have been collected for many reasons, biodiversity monitoring being one of the key applications. Unfortunately, although there are camera trap deployments all over the world, these operations occur in isolation, limiting the impact they could have on a global understanding of biodiversity health. Even within individual institutions, managing and analyzing multiple camera trap deployments in aggregate can be challenging. In fact, managing a single deployment of camera traps is non-trivial and important data are frequently cast aside as bycatch, left unanalyzed on decaying hard drives. Wildlife Insights attempts to overcome these hurdles by providing camera trap data upload, management, and analysis services. It provides the world’s largest database of camera trap images by bringing together the camera trapping efforts of several the world’s largest conservation and research organizations, and it is open to future contributors. Artificial Intelligence-driven services sit at the heart of the platform. New camera trap data uploads are automatically analyzed to differentiate between images with people, non-human animals, and no animals. The images with non-human animals are further analyzed to detect specific species. The proposed labels are sent back to the submitter for review and then uploaded to the database. All uploaded images, unless specifically embargoed, are immediately available for analysis by all users of the system. A selection of tools are provided to support analyses of global biodiversity. This presentation will describe Wildlife Insights and its AI implementation in detail, contextualized by case studies using analyses of the data currently stored on the platform. Challenges around integrating camera trap data within the platform and with other external services that work with the platform will also be discussed. The talk will end with some thoughts about future directions for the AI services, especially with regards to integration with related platforms.

Habitat use and diel activity pattern of the Tibetan Snowcock (Tetraogallus tibetanus): a case study using camera traps for surveying high-elevation bird species

BackgroundGlobal climate change has had significant effects on animal distribution and population dynamics in mid-latitude alpine areas, but we know little about the basic ecology of high-altitude species due to the difficulties of conducting field research in the harsh climate and habitat present at high elevations. The Tibetan Snowcock (Tetraogallus tibetanus) is a little-known phasianid distributing in alpine areas at extremely high elevations in the mountains surrounding the Tibetan Plateau. Estimating the species occupancy rate and discussing the factors affecting its distribution based on infrared-triggered camera techniques would provide both a baseline to measure the influence of global warming and valuable information on its conservation and ecology.MethodsWe used infrared-triggered cameras to investigate the Tibetan Snowcock on the western slope of Mt. Gongga from June to November 2016. We used the R package “overlap” to visualize its activity pattern, and used an occupancy model to both examine its habitat use as well as to determine the most influential variables affecting its habitat use.ResultsUsing 103 camera traps over 9213 camera-days, we recorded 428 instances of Tibetan Snowcock. The diel activity peaks of Tibetan Snowcock occurred during the periods of 8:00‒10:00 am and 18:00‒20:00 pm. The model estimate of occupancy for Tibetan Snowcock (0.830) was slightly higher than the naïve site occupancy based on camera detections (0.663), indicating a wider use of habitat than the camera traps recorded. Elevation, slope, settlement density, road density, and EVI (enhanced vegetation index) were the most influential variables for its habitat use.ConclusionsThe Tibetan Snowcock is confirmed to be diurnal. This species prefers an environment with a high elevation, gentle slope, and low EVI, apparently facing a trade-off between predator risk, foraging efficiency, and food availability. When human impact was low, there was a positive correlation between the habitat use of the Tibetan Snowcock and both its road and settlement densities. Infrared cameras and proper survey design are valuable for investigating extreme alpine phasianids.

Parental attendance of Chestnut Thrush reduces nest predation during the incubation period: compensation for low nest concealment?

A well-concealed nest site is supposed to reduce nest predation risk; however, the expected positive relationship between nest concealment and nest survival does not exist in some passerine species, especially in thrushes. Previous studies have suggested thrushes might be capable of defending their nest against predators and do provide compensation for their low nest concealment, but this mechanism is controversial. We conducted a field experiment on the Chestnut Thrush (Turdus rubrocanus) to test whether parental attendance reduced nest predation risk, and to explore the possible mechanism behind this. In this study, we found that natural nests (with parental attendance) suffered lower nest predation rate than paired re-used nests (without parental attendance). With infrared-triggered cameras, we observed that Chestnut Thrush successfully defended their nests against mice. We identified mice as the main predator in re-used nests, while nest concealment had no significant impact on mice predation. Overall, parental attendance of the Chestnut Thrushes reduced the nest predation risk by deterring opportunistic predators, but not enough to offset the low nest concealment.

Using Infrared-Triggered Cameras to Monitor Activity of Forest Carnivores

The activity patterns of 4 forest predator species were monitored, using infrared-triggered cameras, within a 1318-ha study area in East Texas. We recorded 161 photographic capture events in 1925 trap-nights over 17 weeks. Photographic capture events included 18 Lynx rufus (Bobcat), 109 Procyon lotor (Raccoon), 21 Didelphis virginiana (Virginia Opossum), and 13 Canis latrans (Coyote). We developed an easily replicated method of measuring time on a percent scale to compare activity data over several months, accounting for changes in sunrise and sunset times. Bobcat activity was 38.9% crepuscular and 22.1% diurnal. The activity of the other 3 species was mostly nocturnal: Raccoon 94.5%, Virginia Opossum 100%, and Coyote 77%. Moon phase based on percentage of visible light did not affect either Raccoon or Virginia Opossum nocturnal activity level.

Nest caging as a conservation tool for threatened songbirds

Context Enclosing nests in cages to exclude predators is a management tool frequently used to increase the reproductive success of threatened ground-nesting precocial birds. This technique has seldom been used with passerines, despite the predicted increased benefit for altricial species due to their longer period of nest dependency. Aims The aims of this study were to determine (1) whether cages could be installed around the nests of a threatened, shrub-nesting passerine without causing parental desertion, and (2) whether caged nests could successfully exclude the dominant nest predators and increase nesting success. Methods Cages with four different mesh sizes (1000 mm, 200 mm, 100 mm, 50 mm) were installed sequentially in trials at four nests in a secure population and three nests in an endangered population of white-fronted chats (Epthianura albifrons) to investigate susceptibility to desertion. Trials using 160 caged and uncaged artificial nests were used to determine the efficacy of 50-mm wire mesh in preventing access to eggs by potential nest predators. Key results Parent birds accepted nest cages, which reduced predation rates on artificial nests from 96% to 14%. Infrared-triggered cameras revealed that corvids were responsible for 94% of predation episodes. Nest success of caged white-fronted chat nests was 85% (n = 7). Conclusions Nest cages do not appear to have negative effects on nest success of white-fronted chats, and may considerably increase reproductive success. Implications Nest cages may aid conservation of the endangered population of white-fronted chats and other endangered songbird species.

Water Developments and Canids in Two North American Deserts: A Test of the Indirect Effect of Water Hypothesis

Anthropogenic modifications to landscapes intended to benefit wildlife may negatively influence wildlife communities. Anthropogenic provisioning of free water (water developments) to enhance abundance and distribution of wildlife is a common management practice in arid regions where water is limiting. Despite the long-term and widespread use of water developments, little is known about how they influence native species. Water developments may negatively influence arid-adapted species (e.g., kit fox, Vulpes macrotis) by enabling water-dependent competitors (e.g., coyote, Canis latrans) to expand distribution in arid landscapes (i.e., indirect effect of water hypothesis). We tested the two predictions of the indirect effect of water hypothesis (i.e., coyotes will visit areas with free water more frequently and kit foxes will spatially and temporally avoid coyotes) and evaluated relative use of free water by canids in the Great Basin and Mojave Deserts from 2010 to 2012. We established scent stations in areas with (wet) and without (dry) free water and monitored visitation by canids to these sites and visitation to water sources using infrared-triggered cameras. There was no difference in the proportions of visits to scent stations in wet or dry areas by coyotes or kit foxes at either study area. We did not detect spatial (no negative correlation between visits to scent stations) or temporal (no difference between times when stations were visited) segregation between coyotes and kit foxes. Visitation to water sources was not different for coyotes between study areas, but kit foxes visited water sources more in Mojave than Great Basin. Our results did not support the indirect effect of water hypothesis in the Great Basin or Mojave Deserts for these two canids.

Effectiveness of cattle operated bump gates and exclusion fences in preventing ungulate multi-host sanitary interaction

Tuberculosis (TB) is endemic in Eurasian wild boar (Sus scrofa) and red deer (Cervus elaphus) in south central Spain, where evidence suggests transmission to domestic cattle. Known risk factors for TB at the interface between livestock and wild ungulate species include density and spatial overlap, particularly around waterholes during summer. We evaluated the effectiveness of selective exclusion measures for reducing direct and indirect interaction between extensive beef cattle and wild ungulates at waterholes as an alternative for the integrated control of TB. We first monitored 6 water points (WP) with infrared-triggered cameras at a TB positive cattle farm to quantify interactions. We then assigned 3 WP to be “cattle-only” and 3 to be “wildlife-only”. Cattle-only WP were surrounded with a wildlife-proof fence (2.5m high) and an original design of cattle-specific gate. Wildlife-only WP were surrounded by a fence that wild ungulates could breach but cattle could not (1.2m high). Red deer, roe deer (Capreolus capreolus) and wild boar easily jumped or undercrossed this fence. Wildlife-only fences were 100% effective in preventing cattle access to WP and did not impede wildlife use. Many cows learned to operate the cattle-specific gate quickly and others followed and learned from them. Within 2 weeks, around 70% of cows actively entered and exited through the cattle-specific gate. We demonstrate how simple, low-cost fencing strategies can serve as biosecurity measures to substantially reduce direct and indirect contact between cattle and wild ungulates, serving to reduce the potential for TB transmission. Our designs can be used in the context of integral plans to mitigate disease transmission between cattle and wildlife, and have potential for protecting or segregating the use of a variety of resources in different contexts.

Vigilance of kit foxes at water sources: A test of competing hypotheses for a solitary carnivore subject to predation

Animals that are potential prey do not respond equally to direct and indirect cues related to risk of predation. Based on differential responses to cues, three hypotheses have been proposed to explain spatial variation in vigilance behavior. The predator-vigilance hypothesis proposes that prey increase vigilance where there is evidence of predators. The visibility-vigilance hypothesis suggests that prey increase vigilance where visibility is obstructed. Alternatively, the refuge-vigilance hypothesis proposes that prey may perceive areas with low visibility (greater cover) as refuges and decrease vigilance. We evaluated support for these hypotheses using the kit fox (Vulpes macrotis), a solitary carnivore subject to intraguild predation, as a model. From 2010 to 2012, we used infrared-triggered cameras to record video of kit fox behavior at water sources in Utah, USA. The refuge-vigilance hypothesis explained more variation in vigilance behavior of kit foxes than the other two hypotheses (AICc model weight=0.37). Kit foxes were less vigilant at water sources with low overhead cover (refuge) obstructing visibility. Based on our results, the predator-vigilance and visibility-vigilance hypotheses may not be applicable to all species of prey. Solitary prey, unlike gregarious prey, may use areas with concealing cover to maximize resource acquisition and minimize vigilance.

Bobcats Exhibit Low Detection Rates at Hair Collection Stations in East Texas

We evaluated the detection rate for hair snare sampling for bobcats (Lynx rufus) using collocated hair snares and infrared-triggered cameras at 20 locations on private property in eastern Texas. Hair snare and camera stations were located together and included both visual and olfactory attractants. In 1,680 trap-nights we photographically documented 15 visits by bobcats but collected only one bobcat hair sample. Our observations suggested limited rubbing behavior by bobcats at hair snares and did not support any influence by sympatric carnivores (e.g., gray fox, Urocyon cinereoargenteus). Low rub frequency may limit the utility of these techniques for bobcats and we suggest that alternate techniques such as camera surveys or fecal DNA collection may be more suitable.

Assessment of temporal partitioning in foraging patterns of syntopic Virginia opossums and raccoons

Temporal partitioning in foraging patterns of syntopic Virginia opossums (Didelphis virginiana) and raccoons (Procyon lotor) was investigated at 3 sites in western Tennessee through the use of timers attached to live traps on trapping grids and through time-stamped remote photography using infrared-triggered cameras at bait stations. Data were analyzed using Watson’s U 2 -test, chi-square analyses, and probability tests. Results revealed no intraspecific differences in time of foraging for either species and a lack of interspecific differentiation. A high degree of overlap in foraging times of the species was observed. Virginia opossums and raccoons apparently did not partition their times of foraging. Foraging patterns of each species seem to be independent of the other (neutral association).

Estimating Deer Abundance in Suburban Areas with Infrared-Triggered Cameras

Interactions between humans and white-tailed deer (Odocoileus virginianus) have become common, often resulting in management actions to mitigate negative impacts. Changes in population size are generally used to judge management actions. We examined deer population estimation techniques during 2 mark-resighting experiments in a woodland- grassland habitat in central New York State and in a suburban area. We compared program NOREMARK, Lincoln-Peterson estimates, and Jacobson's (1997) buck:doe ratios (BDR) for estimating deer abundance. In the fi rst fi eld trial, we sought to validate the camera survey methods and computer applications. We used infrared-triggered cameras (IRCs) to survey a white-tailed deer population of known size that inhabited a fenced, woodland-grassland area (11-day survey, 1 camera/33 ha, fall 1999). We estimated deer abundance with program NOREMARK (Bowden estimator). Analysis of the photographic data with this technique produced an accurate and precise population estimate in the fi rst experiment. In the second experiment, we used program NOREMARK and 2 similar estimators in a previously untested suburban landscape. We surveyed a suburban white-tailed deer population with IRCs during spring and fall 2000 (10-day surveys, 1 camera/38 ha), using program NOREMARK (Bowden estimator), the Jacobson BDR method, and the Lincoln-Peterson estimator. All 3 methods produced similar estimates of deer abundance. We concluded that IRCs, in conjunction with either program NOREMARK or the Jacobson BDR method will provide reliable estimates of deer abundance in suburban areas.

Habitat selection and current distribution of the pygmy rabbit in Nevada and California, USA

We surveyed the historic range of pygmy rabbits (Brachylagus idahoensis) in Nevada and California using infrared-triggered cameras to determine the species’ current distribution and habitat selection. Areas with potential habitat were mapped using geographical information system coverages for elevation, big sagebrush (Artemisia tridentata) vegetation, and loamy soils. Within this region random sites and field-selected sites with sagebrush islands (prominent clusters of sagebrush higher than the surrounding sagebrush) were surveyed for the presence of pygmy rabbits. Sites were measured for sagebrush height, surrounding sagebrush height, sagebrush cover, and soil composition. Likelihood of pygmy rabbit occupancy at a site increased with the presence of sagebrush islands, increasing sagebrush cover, and decreasing surrounding sagebrush height. Additionally, we surveyed 1,394 other sites across the species’ historic range and found current activity of pygmy rabbits at 258 of these sites. We measured sagebrush cover, sagebrush height, understory stem density, and presence or absence of cottontail rabbits, jackrabbits, red soils, cheatgrass, and rodent burrows at 454 sites. We used 80% of the data to create a logistic regression model. The top-ranked Akaike’s information criterion–selected model suggested that likelihood of pygmy rabbit occupancy at a site increased with increasing sagebrush cover, decreasing understory stem density, absence of cottontails, absence of reddish soils, absence of cheatgrass, and absence of rodent burrows. This model showed a 79% accuracy rate in predicting occupancy within the remaining data. Current populations of pygmy rabbits were found throughout all of the species’ historic range in Nevada and the southern portion of its range in California.

CENSUSING BOBCATS USING REMOTE CAMERAS

We estimated bobcat (Lynx rufus) density for 3 different locations in northern California using active infrared-triggered cameras. Using differences in pelage pattern as well as other physical characteristics, we identified individual bobcats from photographs, and used mark-recapture techniques to estimate population density. Camera density affected the precision of population estimates. The same population was estimated using camera densities of 0.5, 1, 2, 4, 6, and 8 cameras ⋅ km-2. Higher camera densities resulted in more captures and recaptures of bobcats and, conse- quently, in more precise density estimates. Similarly, the number of photo-captures and recaptures increased with increasing study duration. Increasing the area sampled resulted in the capture of more individuals but did not increase the percentage of recaptures. While some locations captured multiple bobcat photographs (e.g., 15 at 1 station), these photos tended to be recaptures of the same individual. There were no more than 2 individuals photo-captured at any 1 camera location. Bobcat density varied among habitat types as predicted. We estimated density as 0.27 bobcats ⋅ km-2 (s = 0.16) overall in an area in the northern Sacramento River Valley and as 0.35 bobcats ⋅ km-2 (s = 0.56) in a steep and rocky canyon within the area. At a 3rd site in the Coast Range, the estimate was 0.39 bobcats ⋅ km-2 (s = 1.44). Bobcats were more diurnal where human activity was less common. In addition, photo-capture was significantly higher along roads and trails without an attractant than it was off-trail with an attractant.

Habitat Use by Introduced Raccoons and Native Raccoon Dogs in a Deciduous Forest of Japan

We investigated habitat use by introduced raccoons (Procyon lotor) and native raccoon dogs (Nyctereutes procyonoides albus) in a northern deciduous forest of Japan to examine the relationship between the 2 species. Spatial and temporal habitat use in the forest was monitored using infrared-triggered cameras. We also surveyed environmental factors at 2 spatial scales: at the macrohabitat scale, we examined forest growth stage, forest fragmentation, and distance from a water source; at the microhabitat scale, we examined forest structure, understory vegetation, and beetle abundance. We then analyzed the relationship between environmental factors and habitat use by each species using generalized linear model. Except for fern coverage, most environmental factors at the micro- and macrohabitat scales had different effects on the habitat use of these species. Moreover, the degree of diurnal activity also differed between the species. These spatial and temporal differences in habitat use between raccoons and raccoon dogs provide further evidence that competition between these 2 species may be limited in this area.