Animal‐borne video systems provide insight into the reproductive behavior of the Asian black bear

Previous studies on the mating system of the Asian black bear (Ursus thibetanus) have been limited to observations of captive populations and estimations of multiple paternities. Hence, the mating system of wild bears remains poorly understood. Animal‐borne camera systems (i.e., cameras mounted on animals) provide novel tools to study the behavior of elusive animals. Here, we used an animal‐borne video system to record the activities of wild bears during the mating season. Video camera collars were attached to four adult Asian black bears (male “A” and “B,” and female “A” and “B”) captured in Tokyo, central Japan, in May and June 2018. The collars were retrieved in July 2018, after which the video data were downloaded and analyzed in terms of bear activity and mating behavior. All the bears were found to interact with other uniquely identifiable bears for some of the time (range 9–22 days) during the deployment period (range 36–45 days), and multiple mating in males was documented. Both males and females exhibited different behaviors on social days (i.e., days when the bear interacted with conspecifics) compared with solitary days (i.e., days with no observed interactions with conspecifics). Compared with solitary days, the bears spent a lower proportion of time on foraging activities and higher proportion of time on resting activities on social days. Our results suggest that Asian black bears have a polygamous mating system, as both sexes consort and potentially mate with multiple partners during a given mating season. Furthermore, bears appeared to reduce their foraging activities on social days and engaged more in social interactions.     

Habitat occupancy of sloth bear Melursus ursinus in Chitwan National Park,Nepal

Mammals have experienced a massive decline in their populations and geographic ranges worldwide. The sloth bear, Melursus ursinus (Shaw, 1791), is one of many species facing conservation threats. Despite being endangered in Nepal, decades of inattention to the situation have hindered their conservation and management. We assessed the distribution and patterns of habitat use by sloth bears in Chitwan National Park (CNP), Nepal. We conducted sign surveys from March to June, 2020, in 4 × 4 km grids (n = 45). We collected detection/non‐detection data along a 4‐km trail that was divided into 20 continuous segments of 200 m each. We obtained environmental, ecological, and anthropogenic covariates to understand determinants of sloth bear habitat occupancy. The data were analyzed using the single‐species single‐season occupancy method, with a spatially correlated detection. Using repeated observations, these models accounted for the imperfect detectability of the species to provide robust estimates of habitat occupancy. The model‐averaged occupancy estimate for the sloth bear was 69% and the detection probability was 0.25. The probability of habitat occupancy by sloth bears increased with the presence of termites and fruits and in rugged, dry, open, undisturbed habitats. Our results indicate that the sloth bear is elusive, functionally unique, and widespread in CNP. Future conservation interventions and action plans aimed at sloth bear management must adequately consider their habitat requirements.     

Fine‐scale ecological and anthropogenic variables predict the habitat use and detectability of sloth bears in the Churia habitat of east Nepal

Once widespread throughout the tropical forests of the Indian Subcontinent, the sloth bears have suffered a rapid range collapse and local extirpations in the recent decades. A significant portion of their current distribution range is situated outside of the protected areas (PAs). These unprotected sloth bear populations are under tremendous human pressures, but little is known about the patterns and determinants of their occurrence in most of these regions. The situation is more prevalent in Nepal where virtually no systematic information is available for sloth bears living outside of the PAs. We undertook a spatially replicated sign survey‐based single‐season occupancy study intending to overcome this information gap for the sloth bear populations residing in the Trijuga forest of southeast Nepal. Sloth bear sign detection histories and field‐based covariates data were collected between 2 October and 3 December 2020 at the 74 randomly chosen 4‐km² grid cells. From our results, the model‐averaged site use probability (ψ ± SE) was estimated to be 0.432 ± 0.039, which is a 13% increase from the naïve estimate (0.297) not accounting for imperfect detections of sloth bear signs. The presence of termite mound and the distance to the nearest water source were the most important variables affecting the habitat use probability of sloth bears. The average site‐level detectability (p ± SE) of sloth bear signs was estimated to be 0.195 ± 0.003 and was significantly determined by the index of human disturbances. We recommend considering the importance of fine‐scale ecological and anthropogenic factors in predicting the sloth bear‐habitat relationships across their range in the Churia habitat of Nepal, and more specifically in the unprotected areas.     

Dining from the coast to the summit: Salmon and pine nuts determine the summer body condition of female brown bears on the Shiretoko Peninsula

Body condition in mammals fluctuates depending on energy intake and expenditure. For brown bears (Ursus arctos), high‐protein foods facilitate efficient mass gain, while lipids and carbohydrates play important roles in adjusting dietary protein content to optimal levels to maximize energy intake. On the Shiretoko Peninsula, Hokkaido, Japan, brown bears have seasonal access to high‐lipid pine nuts and high‐protein salmon. To assess seasonal and annual fluctuation in the body condition of adult female brown bears in relation to diet and reproductive status, we conducted a longitudinal study in a special wildlife protection area on the Shiretoko Peninsula during 2012–2018. First, analyses of 2,079 bear scats revealed that pine nuts accounted for 39.8% of energy intake in August and salmon accounted for 46.1% in September and that their consumption by bears varied annually. Second, we calculated the ratio of torso height to torso length as an index of body condition from 1,226 photographs of 12 adult females. Results indicated that body condition continued to decline until late August and started to increase in September when salmon consumption increased. In addition, body condition began to recover earlier in years when consumption of both pine nuts and salmon was high. Furthermore, females with offspring had poorer body condition than solitary females, in particular in late August in years with low salmon consumption. Our findings suggest that coastal and subalpine foods, which are unique to the Shiretoko Peninsula, determine the summer body condition of female brown bears, as well as their survival and reproductive success.     

Directness of resource use metrics affects predictions of bear body fat gain

Many North American ursids rely on an annual hyperphagic period to obtain fat reserves necessary for winter survival and reproduction. Identifying causes of variation in body fat gain may improve understanding of how bear resource use affects body condition. We used data from southcentral Alaska to model changes in percentage body fat of adult female American black bears (Ursus americanus) in 1998 and 2000 and brown bears (Ursus arctos) in 2000. We used year, proportion of radio locations in different habitats, distance to streams containing salmon (Onchorynchus spp.), and degree of radio location clustering as predictors for black bears and elevation, distance to streams containing salmon, and degree of radio location clustering as predictors for brown bears. Degree of location clustering was the only predictor variable supported by parameter coefficients in black bear models, supporting our hypothesis that metrics of energetics perform better as predictors of body condition than habitat use. With every unit increase in location clustering black bear body fat increased 2 %. No predictor variables influenced variation in brown bear change in body fat. Some variables previously found useful for predicting bear presence (e.g., habitat) were not useful in predicting changes in body fat, an important biological outcome for these species. Rather than assuming fitness benefits of habitat-level selection, we recommend including metrics of energetics that might more directly influence biological outcomes.     

Beyond the encounter: Predicting multi‐predator risk to elk (Cervus canadensis) in summer using predator scats

1. There is growing evidence that prey perceive the risk of predation and alter their behavior in response, resulting in changes in spatial distribution and potential fitness consequences. Previous approaches to mapping predation risk across a landscape quantify predator space use to estimate potential predator‐prey encounters, yet this approach does not account for successful predator attack resulting in prey mortality. An exception is a prey kill site that reflects an encounter resulting in mortality, but obtaining information on kill sites is expensive and requires time to accumulate adequate sample sizes.
2. We illustrate an alternative approach using predator scat locations and their contents to quantify spatial predation risk for elk (Cervus canadensis) from multiple predators in the Rocky Mountains of Alberta, Canada. We surveyed over 1300 km to detect scats of bears (Ursus arctos/U. americanus), cougars (Puma concolor), coyotes (Canis latrans), and wolves (C. lupus). To derive spatial predation risk, we combined predictions of scat‐based resource selection functions (RSFs) weighted by predator abundance with predictions that a predator‐specific scat in a location contained elk. We evaluated the scat‐based predictions of predation risk by correlating them to predictions based on elk kill sites. We also compared scat‐based predation risk on summer ranges of elk following three migratory tactics for consistency with telemetry‐based metrics of predation risk and cause‐specific mortality of elk.
3. We found a strong correlation between the scat‐based approach presented here and predation risk predicted by kill sites and (r = .98, p < .001). Elk migrating east of the Ya Ha Tinda winter range were exposed to the highest predation risk from cougars, resident elk summering on the Ya Ha Tinda winter range were exposed to the highest predation risk from wolves and coyotes, and elk migrating west to summer in Banff National Park were exposed to highest risk of encountering bears, but it was less likely to find elk in bear scats than in other areas. These patterns were consistent with previous estimates of spatial risk based on telemetry of collared predators and recent cause‐specific mortality patterns in elk.
4. A scat‐based approach can provide a cost‐efficient alternative to kill sites of quantifying broad‐scale, spatial patterns in risk of predation for prey particularly in multiple predator species systems.

     

Survival and abundance of polar bears in Alaska’s Beaufort Sea, 2001–2016

The Arctic Ocean is undergoing rapid transformation toward a seasonally ice‐free ecosystem. As ice‐adapted apex predators, polar bears (Ursus maritimus) are challenged to cope with ongoing habitat degradation and changes in their prey base driven by food‐web response to climate warming. Knowledge of polar bear response to environmental change is necessary to understand ecosystem dynamics and inform conservation decisions. In the southern Beaufort Sea (SBS) of Alaska and western Canada, sea ice extent has declined since satellite observations began in 1979 and available evidence suggests that the carrying capacity of the SBS for polar bears has trended lower for nearly two decades. In this study, we investigated the population dynamics of polar bears in Alaska''s SBS from 2001 to 2016 using a multistate Cormack–Jolly–Seber mark–recapture model. States were defined as geographic regions, and we used location data from mark–recapture observations and satellite‐telemetered bears to model transitions between states and thereby explain heterogeneity in recapture probabilities. Our results corroborate prior findings that the SBS subpopulation experienced low survival from 2003 to 2006. Survival improved modestly from 2006 to 2008 and afterward rebounded to comparatively high levels for the remainder of the study, except in 2012. Abundance moved in concert with survival throughout the study period, declining substantially from 2003 and 2006 and afterward fluctuating with lower variation around an average of 565 bears (95% Bayesian credible interval [340, 920]) through 2015. Even though abundance was comparatively stable and without sustained trend from 2006 to 2015, polar bears in the Alaska SBS were less abundant over that period than at any time since passage of the U.S. Marine Mammal Protection Act. The potential for recovery is likely limited by the degree of habitat degradation the subpopulation has experienced, and future reductions in carrying capacity are expected given current projections for continued climate warming.     

Contrasting Activity Patterns of Sympatric and Allopatric Black and Grizzly Bears

ABSTRACT The distribution of grizzly (Ursus arctos) and American black bears (U. americanus) overlaps in western North America. Few studies have detailed activity patterns where the species are sympatric and no studies contrasted patterns where populations are both sympatric and allopatric. We contrasted activity patterns for sympatric black and grizzly bears and for black bears allopatric to grizzly bears, how human influences altered patterns, and rates of grizzly-black bear predation. Activity patterns differed between black bear populations, with those sympatric to grizzly bears more day-active. Activity patterns of black bears allopatric with grizzly bears were similar to those of female grizzly bears; both were crepuscular and day-active. Male grizzly bears were crepuscular and night-active. Both species were more night-active and less day-active when ≤1 km from roads or developments. In our sympatric study area, 2 of 4 black bear mortalities were due to grizzly bear predation. Our results suggested patterns of activity that allowed for intra- and inter-species avoidance. National park management often results in convergence of locally high human densities in quality bear habitat. Our data provide additional understanding into how bears alter their activity patterns in response to other bears and humans and should help park managers minimize undesirable bear-human encounters when considering needs for temporal and spatial management of humans and human developments in bear habitats.     

Increased brown bear predation on sika deer fawns following a deer population irruption in eastern Hokkaido, Japan

By the 1970s, brown bears (Ursus arctos) in Hokkaido, northern Japan, were opportunistic omnivores that mainly depended on plant materials. Because the sika deer (Cervus nippon) population irrupted in eastern Hokkaido in the 1990s, we expected that brown bears might prey on sika deer fawns. First, we developed a simple and cost-effective method of monitoring possible bear predation on deer fawns by analyzing the widths of deer hairs remained in bear scats. Based on hair thickness standards, we distinguished the brown bear consumption of deer fawns from adults by analyzing bear scats (n?=?108) collected during the deer birthing season (late May?Clate July) in 1999?C2008. To evaluate the importance of fawns to bears, we compared the occurrence of fawn and adult deer hairs in bear scats among three periods (I, 1999?C2000; II, 2003?C2005; III, 2006?C2008) in eastern Hokkaido. The occurrence of fawn hairs in bear scats increased from 12.5 to 27.3?% in volume and from 6.3 to 33.6?% in frequency from period I to period III, whereas adult hairs in scats decreased from 42.8 to 26.1?% in volume and from 34.4 to 22.7?% in frequency during the same time. These data suggest that bears increasingly preyed on deer fawns after the deer population irruption and decreasingly used adult carcasses because of the enforcement of deer carcass treatment by the Hokkaido government.     

Resource Selection by Recolonizing American Black Bears

American black bears (Ursus americanus) were extirpated from Oklahoma, USA, in the early twentieth century but have since recolonized eastern portions of the state after immigrating from Arkansas, where they were successfully translocated. Within the last 2 decades, a population of black bears was detected in the Oklahoma Ozark region, prompting studies to determine population size, growth rate, and genetic makeup. To understand how black bears were recolonizing the human-dominated landscape, we investigated resource selection at 2 scales. Between 2011 and 2016, we collected global positioning system collar spatial data for 10 males and 13 females. We calculated average kernel density home ranges on a seasonal scale for all collared bears. We used generalized linear mixed models to calculate resource selection functions at the study area, defined by locations of all radio-collared black bears (second order) and the scale of individual black bear home ranges (third order). Resource selection did not differ significantly by sex. Black bears across seasons and scales selected riparian forest and moist oak (Quercus spp.) forest land cover types and mostly selected against indicators of human activity (e.g., pasture-prairie, anthropogenic land cover types, roads, and areas of high human population density). Black bears also selected areas with rugged terrain at high elevations, although not consistently across seasons and scales. Black bear recolonization appeared to be negatively affected by areas and features characterized as human-altered. Further expansion of the range of black bears may be limited by anthropogenic disturbance in the region. © 2021 The Wildlife Society.     

The diet of polar bears (Ursus maritimus) from Svalbard, Norway, inferred from scat analysis

Polar bears (Ursus maritimus) are heavily dependent on marine prey, in particular ice-associated seals, which they hunt on landfast sea ice or free-floating pack ice. Dramatic current (and predicted) losses of sea ice habitat make it increasingly important to gain more knowledge of the relative use by bears of all types of prey from the marine food web as well as from terrestrial sources. This study uses frequency of occurrence of food items in 119 polar bear scats sampled on the sea ice as well as on shore in coastal areas in the Svalbard Archipelago, mainly in spring, between 2003 and 2010 to explore the diet of bears in the region. Ringed seals (Pusa hispida) occurred in 62.2 % (CI 52.8–70.9 %) of the scat samples examined. Various terrestrial plants (32.8 %, CI 24.4–42.0 %) and marine algae (21.8 %, CI 14.8–30.4 %) also occurred frequently in the scats; the significance of this high occurrence of plants and algae is not clear. Bearded seals (Erignathus barbatus) and various bird species constituted only minor components of the diet, while Svalbard reindeer (Rangifer tarandus platyrhynchus) occurred in 9.2 % (CI 4.7–15.9 %) of the scats, indicating that this species may play a more important role than previously reported. The novel combination of genetic analyses of material in the fecal samples along with detailed exploration of the physical–structural properties of prey hairs and plant parts provided a much fuller picture of the diet of polar bears than would have been possible from observational studies of polar bear predation behavior alone. This approach may provide an important tool for monitoring the responses of polar bears to ongoing ecosystem changes that will result from continued warming in the Arctic.     

Estimates of resource transfer via winged adult insects from the hyporheic zone in a gravel‐bed river

Hyporheic zone (HZ) locates below the riverbed providing habitat for macroinvertebrates from where the winged adult insects (i.e., hyporheic insects, HIs) emerge and bring out aquatic resources to the riparian zone. This study estimated mean daily flux as dry biomass (BM), carbon (C), and nitrogen (N) deriving from the dominant HI species Alloperla ishikariana (Plecoptera, Chloroperlidae) for a 4th‐order gravel‐bed river during the early‐summer to summer periods. We hypothesized that HIs were an important contributor in total aquatic resources to the riparian zone. In 2017 and 2018, we set parallelly (May to August) and perpendicularly (June to October) oriented Malaise traps to catch the lateral and longitudinal directional dispersing winged adults of A. ishikariana, and other Ephemeroptera, Plecoptera, Trichoptera, and Diptera from the river and estimated the directional fluxes of them. We further split the directional fluxes as moving away or back to the channel (for lateral) and from down‐ to upstream or up‐ to downstream (for longitudinal). Alloperla ishikariana was similar to other Plecoptera species and differed clearly from Ephemeroptera and Trichoptera in directional characteristics of resources flux, suggesting that the extent and directions of HZ‐derived resource transfer depend on taxon‐specific flight behaviors of HIs. Contributions of A. ishikariana to the riparian zone in total aquatic C and N transfer seasonally varied and were lower in May (5%–6%) and August (2%–4%) and the highest in July (52%–70%). These conservative estimates largely increased (9% in May) after the supplementary inclusion of Diptera (Chironomidae and Tipulidae), part of which were considered HIs. We demonstrated that HZ could seasonally contribute a significant portion of aquatic resources to the riparian zone and highlighted the potential importance of HZ in nutrient balance in the river‐riparian ecosystem.     

Habitat use by black bears in relation to conspecifics and competitors

Sympatric black bears (Ursus americanus) and brown bears (Ursus arctos) are common in many boreal systems; however, few predator assemblages are known to coexist on a single seasonally abundant large prey item. In lowland southwestern interior Alaska, black bears and brown bears are considered the primary cause of moose (Alces alces) calf mortality during the first 6 weeks of life. The objective of this study was to document habitat use of global-positioning system (GPS)-collared black bears during peak and non-peak seasons of black bear-induced and brown bear-induced moose calf mortality within southwestern interior Alaska, in spring 2002. We compared habitats of GPS-collared black bears to those of presumably uncollared black bears and brown bears at their moose calf mortality sites. Results from this study suggest that GPS-collared black bears use similar habitat as conspecifics more than expected during the peak period of black bear predation on moose calves, whereas they use habitat in proportion to home range availability during the peak in brown bear predation on moose calves. Sex-specific Ivlev's electivity indices describe greater than expected use of mixed-deciduous forest and needleleaf forest by male GPS-collared black bears during the peak of moose calf predation, whereas females have a tendency to use these habitats less than expected. Juvenile GPS-collared black bears largely use the same habitat as other sympatric predators during the peak of moose calf predation, whereas during the non-peak period juveniles use opposite habitats as adult GPS-collared black bears. The outcome of this study offers possible explanations (e.g., sex, age) for spatial overlap or segregation in one member of a complex predator guild in relation to a seasonal pulse of preferred prey.     

White‐tailed deer exploit temporal refuge from multi‐predator and human risks on roads

Although most prey have multiple predator species, few studies have quantified how prey respond to the temporal niches of multiple predators which pose different levels of danger. For example, intraspecific variation in diel activity allows white‐tailed deer (Odocoileus virginianus) to reduce fawn activity overlap with coyotes (Canis latrans) but finding safe times of day may be more difficult for fawns in a multi‐predator context. We hypothesized that within a multi‐predator system, deer would allocate antipredation behavior optimally based on combined mortality risk from multiple sources, which would vary depending on fawn presence. We measured cause‐specific mortality of 777 adult (>1‐year‐old) and juvenile (1–4‐month‐old) deer and used 300 remote cameras to estimate the activity of deer, humans, and predators including American black bears (Ursus americanus), bobcats (Lynx rufus), coyotes, and wolves (Canis lupus). Predation and vehicle collisions accounted for 5.3 times greater mortality in juveniles (16% mortality from bears, coyotes, bobcats, wolves, and vehicles) compared with adults (3% mortality from coyotes, wolves, and vehicles). Deer nursery groups (i.e., ≥1 fawn present) were more diurnal than adult deer without fawns, causing fawns to have 24–38% less overlap with carnivores and 39% greater overlap with humans. Supporting our hypothesis, deer nursery groups appeared to optimize diel activity to minimize combined mortality risk. Temporal refuge for fawns was likely the result of carnivores avoiding humans, simplifying diel risk of five species into a trade‐off between diurnal humans and nocturnal carnivores. Functional redundancy among multiple predators with shared behaviors may partially explain why white‐tailed deer fawn predation rates are often similar among single‐ and multi‐predator systems.     

Identifying Habitat Linkages for American Black Bears in North Carolina,USA

ABSTRACT Understanding landscape structure and the role of habitat linkages is important to managing wildlife populations in fragmented landscapes. We present a data-based method for identifying local- and regional-scale habitat linkages for American black bears (Ursus americanus) on the Albemarle-Pamlico Peninsula of North Carolina, USA. We used weights-of-evidence, a discrete multivariate technique for combining spatial data, to make predictions about bear habitat use from 1,771 telemetry locations on 2 study areas (n = 35 bears). The model included 3 variables measured at a 0.2-km² scale: forest cohesion, forest diversity, and forest-agriculture edge density, adequately describing important habitat characteristics for bears on our study area. We used 2 categories of unique habitat conditions to delineate favorable bear habitat, which correctly classified 79.5% of the bear locations in a 10-fold model validation. Forest cohesion and forest-agriculture edge density were the most powerful predictors of black bear habitat use. We used predicted probabilities of bear occurrence from the model to delineate habitat linkages among local and regional areas where bear densities were relatively high. Our models clearly identified 2 of the 3 sites previously recommended for wildlife underpasses on a new, 4-lane highway in the study area. Our approach yielded insights into how landscape metrics can be integrated to identify linkages suitable as habitat and dispersal routes.     

Dietary adjustability of grizzly bears and American black bears in Yellowstone National Park

Grizzly bears (Ursus arctos) and American black bears (U. americanus) are sympatric in much of Yellowstone National Park. Three primary bear foods, cutthroat trout (Oncorhynchus clarki), whitebark pine (Pinus albicaulis) nuts, and elk (Cervus elaphus), have declined in recent years. Because park managers and the public are concerned about the impact created by reductions in these foods, we quantified bear diets to determine how bears living near Yellowstone Lake are adjusting. We estimated diets using: 1) stable isotope and mercury analyses of hair samples collected from captured bears and from hair collection sites established along cutthroat trout spawning streams and 2) visits to recent locations occupied by bears wearing Global Positioning System collars to identify signs of feeding behavior and to collect scats for macroscopic identification of residues. Approximately 45 ± 22% ( ± SD) of the assimilated nitrogen consumed by male grizzly bears, 38 ± 20% by female grizzly bears, and 23 ± 7% by male and female black bears came from animal matter. These assimilated dietary proportions for female grizzly bears were the same as 10 years earlier in the Lake area and 30 years earlier in the Greater Yellowstone Ecosystem. However, the proportion of meat in the assimilated diet of male grizzly bears decreased over both time frames. The estimated biomass of cutthroat trout consumed by grizzly bears and black bears declined 70% and 95%, respectively, in the decade between 1997–2000 and 2007–2009. Grizzly bears killed an elk calf every 4.3 ± 2.7 days and black bears every 8.0 ± 4.0 days during June. Elk accounted for 84% of all ungulates consumed by both bear species. Whitebark pine nuts continue to be a primary food source for both grizzly bears and black bears when abundant, but are replaced by false-truffles (Rhizopogon spp.) in the diets of female grizzly bears and black bears when nut crops are minimal. Thus, both grizzly bears and black bears continue to adjust to changing resources, with larger grizzly bears continuing to occupy a more carnivorous niche than the smaller, more herbivorous black bear. © 2012 The Wildlife Society.     

Spatial genetic structure and landscape connectivity in black bears: Investigating the significance of using different land cover datasets and classifications in landscape genetics analyses

Landscape genetic analyses allow detection of fine‐scale spatial genetic structure (SGS) and quantification of effects of landscape features on gene flow and connectivity. Typically, analyses require generation of resistance surfaces. These surfaces characteristically take the form of a grid with cells that are coded to represent the degree to which landscape or environmental features promote or inhibit animal movement. How accurately resistance surfaces predict association between the landscape and movement is determined in large part by (a) the landscape features used, (b) the resistance values assigned to features, and (c) how accurately resistance surfaces represent landscape permeability. Our objective was to evaluate the performance of resistance surfaces generated using two publicly available land cover datasets that varied in how accurately they represent the actual landscape. We genotyped 365 individuals from a large black bear population (Ursus americanus) in the Northern Lower Peninsula (NLP) of Michigan, USA at 12 microsatellite loci, and evaluated the relationship between gene flow and landscape features using two different land cover datasets. We investigated the relative importance of land cover classification and accuracy on landscape resistance model performance. We detected local spatial genetic structure in Michigan''s NLP black bears and found roads and land cover were significantly correlated with genetic distance. We observed similarities in model performance when different land cover datasets were used despite 21% dissimilarity in classification between the two land cover datasets. However, we did find the performance of land cover models to predict genetic distance was dependent on the way the land cover was defined. Models in which land cover was finely defined (i.e., eight land cover classes) outperformed models where land cover was defined more coarsely (i.e., habitat/non‐habitat or forest/non‐forest). Our results show that landscape genetic researchers should carefully consider how land cover classification changes inference in landscape genetic studies.     

Seasonal variation in fleshy fruit use and seed dispersal by the Japanese black bear (<Emphasis Type="Italic">Ursus thibetanus japonicus</Emphasis>)

Fruit use by the Japanese black bear (Ursus thibetanus japonicus) and seed clumping in bear scat were studied in central Japan using fecal analyses. Between May and November 2003 and 2004, the life form and fruit size of plants consumed by bears and the species composition and intactness of seeds contained in scat were examined in five transects (approximately 10 km × 10 m) in broad-leaved deciduous forests. In 2003, scats with seeds were found only in the autumn, when fruiting trees and shrubs were abundant. In 2004, scats with seeds occurred intermittently from the summer, when fruiting plants were rare, up to the autumn. Yearly and seasonal variation in fruit use reflects the opportunistic foraging behavior of Japanese black bears. Seven of the nine plant species detected in scats had medium-sized fruits (6–15 mm width), whereas the other two species had relatively large fruits (20–100 mm width). In total, 14,492 seeds were detected, of which 97.6% were intact; the remainder were damaged. Intact seeds of one or two species were found in each scat. The number of intact seeds per scat ranged from 1 to 5476. Japanese black bears seldom digest ingested seeds, thereby contributing to the seed dispersal of their food plants, including species with fruits that are too large to be swallowed by frugivorous birds.     

Effectiveness of Scat Detection Dogs for Detecting Forest Carnivores

Abstract: We assessed the detection and accuracy rates of detection dogs trained to locate scats from free-ranging black bears (Ursus americanus), fishers (Martes pennanti), and bobcats (Lynx rufus). During the summers of 2003-2004, 5 detection teams located 1,565 scats (747 putative black bear, 665 putative fisher, and 153 putative bobcat) at 168 survey sites throughout Vermont, USA. Of 347 scats genetically analyzed for species identification, 179 (51.6%) yielded a positive identification, 131 (37.8%) failed to yield DNA information, and 37 (10.7%) yielded DNA but provided no species confirmation. For 70 survey sites where confirmation of a putative target species' scat was not possible, we assessed the probability that ≤1 of the scats collected at the site was deposited by the target species (probability of correct identification; P_ID). Based on species confirmations or P_ID values, we detected bears at 57.1% (96) of sites, fishers at 61.3% (103) of sites, and bobcats at 12.5% (21) of sites. We estimated that the mean probability of detecting the target species (when present) during a single visit to a site was 0.86 for black bears, 0.95 for fishers, and 0.40 for bobcats. The probability of detecting black bears was largely unaffected by site- or visit-specific covariates, but the probability of detecting fishers varied by detection team. We found little or no effect of topographic ruggedness, vegetation density, or local weather (e.g., temp, humidity) on detection probability for fishers or black bears (data were insufficient for bobcat analyses). Detection dogs were highly effective at locating scats from forest carnivores and provided an efficient and accurate method for collecting detection-nondetection data on multiple species.     

Differential habitat use between demographic states of black bears in managed timber forests

The long-term effects of intensive forest harvest on sensitive demographic stages of the American black bear (Ursus americanus) have been often overlooked. Much of Maine, USA, is covered in forests that are hospitable to bears and commercial timber harvest. To investigate the potential effects of differing intensities of disturbance on black bears, and on females with cubs particularly, we designed a large-scale natural experiment with 197 motion-sensitive camera sites dispersed over representative forest stands in northern and central Maine. Using multi-state occupancy models, we distinguished the overall trends in space use by females with young versus adult bears without young. Forest disturbance at large spatial scales was positively associated with the probability of use for both demographic groups and the availability of hardwood trees was an additional important factor for habitat use by females with young. Our study illustrates the use of motion-sensitive cameras to monitor and understand habitat use by distinct life-history stages of animals living in human-modified landscapes, and results indicate that managers can maintain black bear habitat in areas of active forest harvest by ensuring the availability of hardwood species.