Genetic diversity,effective population size,and structure among black bear populations in the Lower Mississippi Alluvial Valley,USA

Multiple small populations of American black bears Ursus americanus, including the recently delisted Louisiana black bear subspecies U. a. luteolus, occupy a fragmented landscape in the Lower Mississippi Alluvial Valley, USA (LMAV). Populations include bears native to the LMAV, bears translocated from Minnesota during the 1960s, and recently reintroduced and colonizing populations sourced from within the LMAV. We estimated population structure, gene flow, and genetic parameters important to conservation of small populations using genotypes at 23 microsatellite markers for 265 bears from seven populations. We inferred five genetic clusters corresponding to the following populations: White River and western Mississippi, Tensas River and Three Rivers, Upper Atchafalaya, Lower Atchafalaya, and Minnesota. Upper Atchafalaya was suggested as the product of Minnesota-sourced translocations, but those populations have since diverged, likely because of a founder effect followed by genetic drift and isolation. An admixture zone recently developed in northeastern Louisiana and western Mississippi between migrants from White River and Tensas River, resulting in a Wahlund effect. However, gene flow among most populations has been limited and considerable genetic differentiation accumulated (global F_ST?=?0.22), particularly among the three Louisiana black bear populations that existed when federal listing occurred. Consistent with previous bottlenecks, founder effects, and persisting isolation, all LMAV bear populations had low genetic diversity (A_R?=?2.08–4.81; H_E?=?0.36–0.63) or small effective population size (N_E?=?3–49). Translocating bears among populations as part of a regional genetic restoration program may help improve genetic diversity and increase effective population sizes.     

West Nile Virus Exposure in Black Bears of Northeastern Wisconsin

ABSTRACT Knowledge of the distribution and pathology of West Nile virus (WNV) in black bears is a necessary tool that allows wildlife managers to implement a management plan, set harvest quotas, and relocate nuisance bears. We studied the presence and significance of WNV titers in free-roaming black bears (Ursus americanus) in northeastern Wisconsin between February 2003 and March 2005. Serum neutralizing antibodies to WNV, with confirmation by plaque-reduction neutralization test to both WNV and Saint Louis encephalitis, identified exposure in 13 of 74 (17.6%) bears. This compares with a 6% infection rate in black bears in Virginia and 22% in European brown bears (Ursus arctos). Pathologic effects from exposure to WNV were not seen in any of the black bears studied.     

Borreliosis in free-ranging black bears from Wisconsin

Blood, kidney and tick samples were obtained from 18 hunter-killed black bears (Ursus americanus) from three sites in northern Wisconsin. A Borrelia sp., morphologically and antigenically similar to Borrelia burgdorferi, was isolated from the blood of two of the animals, and from the kidney of a third. Ixodes dammini and Dermacentor variabilis were found on the bears. This is the first report of borreliosis in the Ursidae, and of the primary vector of Lyme disease, I. dammini, from this host.     

Effects of Winter Ticks and Internal Parasites on Moose Survival in Vermont,USA

Moose (Alces alces) have experienced considerable declines along the periphery of their range in the northeastern United States. In Vermont, the population declined 45% from 2010 to 2017 despite minimal hunter harvest and adequate habitat. Similarly, nearby populations recently experienced epizootics characterized by >50% mortality. Declines have largely been associated with the effects of winter ticks (Dermacentor albipictus), but uncertainty exists about the effects of environmental and other parasite-related conditions on moose survival. We examined patterns of moose survival among a radio-collared population (n = 127) in Vermont from 2017 to 2019. Our objectives were to estimate causes of mortality and model survival probability as a function of individual and landscape variables for calves (<1 yr) and adults (≥1 yr). Observed adult survival was 90% in 2017, 84% in 2018, and 86% in 2019, and winter calf survival was 60% in 2017, 50% in 2018, and 37% in 2019. Winter tick infestation was the primary cause of mortality (91% of calves, 25% of adults), and 32% of all mortalities had evidence of meningeal worm (Parelaphostrongylus tenuis). Other sources of mortality such as vehicles, harvest, predation, deep snow, and other parasitic infections were negligible. The best supported calf model included sex differences and negative effects of tick engorgement (%/week) and parasite level (roundworm and lungworm). The best supported adult model included the effect of cumulative tick engorgement (cumulative %/week), which negatively affected survival. Our results indicate that winter tick engorgement strongly affects survival, and is probably compounded by the presence of meningeal worm and other parasites. Reduced tick effects may be achieved by decreasing moose density through harvest and managing late winter habitat to minimize tick density. Management of white-tailed deer (Odocoileus virginianus) density may also affect the transmission of meningeal worm. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.     

Potential Species Replacements for Black Ash (<Emphasis Type="Italic">Fraxinus nigra</Emphasis>) at the Confluence of Two Threats: Emerald Ash Borer and a Changing Climate

The emerald ash borer (Agrilus planipennis; EAB) is causing widespread mortality of ash (Fraxinus spp.) and climate change is altering habitats of tree species throughout large portions of North America. Black ash (F. nigra), a moist-soil species common in the Northwoods of Minnesota, Wisconsin, and Michigan, USA, is under a double threat of losing habitat from climate change and near annihilation from EAB. Because black ash often occurs in nearly pure stands, planting non-ash species is a management strategy already underway or being planned for thousands of acres. Tools are needed to assist managers in prioritizing sites for early treatment and to select potential species to replace black ash. This study explores the implications of threats to black ash ecosystems using analyses of field data and models to assess both the threats to, and potential replacement species for, black ash in Minnesota. For our analysis we (1) assessed the status of ashes and co-occurring species in forest inventory plots throughout Minnesota; (2) modeled the risk of EAB attack for multiple years in Minnesota; (3) modeled potential impacts of climate change on tree species with current or potential future habitat in Minnesota; (4) evaluated species co-occurring with black ash in plots in Ohio and Michigan, southeast of Minnesota; and (5) synthesized these results to provide a classification for candidate replacement species, both from within Minnesota and from points farther south. Though this process is demonstrated for black ash in Minnesota, the elements to be considered and modeled would be similar for any other location with a pest or pathogen threat for a species which simultaneously faces a changing climate.     

Blood chemistry of black bears from Pennsylvania during winter dormancy

Twenty-four serum chemistries were measured in blood samples collected from 20 adult female black bears (Ursus americanus) and their offspring, including 14 yearlings and 37 cubs, in northeastern Pennsylvania during winter 1984. Four other captive adult females were bled before, during, and after they were subjected to unseasonably warm temperatures during February. Levels of serum urea nitrogen (SUN) and creatinine were lower (P less than 0.05), and iron was higher (P less than 0.05) in male cubs compared to female cubs; serum chemistries were similar (P greater than or equal to 0.05) between sexes for yearlings. Total protein, albumin and creatinine levels increased with age of bears, whereas chloride, alkaline phosphatase, potassium, inorganic phosphorus and SUN/creatinine were higher (P less than 0.05) in cubs than in yearlings and adults. The relatively high serum calcium in cubs was probably related to rapid bone development and dietary intake of calcium during winter dormancy in cubs. Low serum calcium in adults was attributed to lactation and a lack of dietary intake. Urea/creatinine ratios averaged 5.5 and 4.6 for yearling females and males, respectively, 6.3 for adult females, and 29.0 and 22.8 for female and male cubs, respectively. Levels of serum chemistries of black bears apparently are relatively stable during winter denning, when bears are without food or water and do not urinate or defecate for several months. This stability indicates that black bears are resistant to the extremes in extrinsic environmental conditions. Abnormal blood chemistry values may indicate metabolic stresses that are not being controlled by bears.(ABSTRACT TRUNCATED AT 250 WORDS)     

Integrated Population Modeling of Black Bears in Minnesota: Implications for Monitoring and Management

Background

Wildlife populations are difficult to monitor directly because of costs and logistical challenges associated with collecting informative abundance data from live animals. By contrast, data on harvested individuals (e.g., age and sex) are often readily available. Increasingly, integrated population models are used for natural resource management because they synthesize various relevant data into a single analysis.

Methodology/Principal Findings

We investigated the performance of integrated population models applied to black bears (Ursus americanus) in Minnesota, USA. Models were constructed using sex-specific age-at-harvest matrices (1980–2008), data on hunting effort and natural food supplies (which affects hunting success), and statewide mark–recapture estimates of abundance (1991, 1997, 2002). We compared this approach to Downing reconstruction, a commonly used population monitoring method that utilizes only age-at-harvest data. We first conducted a large-scale simulation study, in which our integrated models provided more accurate estimates of population trends than did Downing reconstruction. Estimates of trends were robust to various forms of model misspecification, including incorrectly specified cub and yearling survival parameters, age-related reporting biases in harvest data, and unmodeled temporal variability in survival and harvest rates. When applied to actual data on Minnesota black bears, the model predicted that harvest rates were negatively correlated with food availability and positively correlated with hunting effort, consistent with independent telemetry data. With no direct data on fertility, the model also correctly predicted 2-point cycles in cub production. Model-derived estimates of abundance for the most recent years provided a reasonable match to an empirical population estimate obtained after modeling efforts were completed.

Conclusions/Significance

Integrated population modeling provided a reasonable framework for synthesizing age-at-harvest data, periodic large-scale abundance estimates, and measured covariates thought to affect harvest rates of black bears in Minnesota. Collection and analysis of these data appear to form the basis of a robust and viable population monitoring program.     

Prevalence of Trichinella spp. in black bears, grizzly bears, and wolves in the Dehcho Region, Northwest Territories, Canada, including the first report of T. nativa in a grizzly bear from Canada

Samples of muscle from 120 black bears (Ursus americanus), 11 grizzly bears (Ursus arctos), and 27 wolves (Canis lupus) collected in the Dehcho Region of the Northwest Territories from 2001 to 2010 were examined for the presence of Trichinella spp. larvae using a pepsin-HCl digestion assay. Trichinella spp. larvae were found in eight of 11 (73%) grizzly bears, 14 of 27 (52%) wolves, and seven of 120 (5.8%) black bears. The average age of positive grizzly bears, black bears, and wolves was 13.5, 9.9, and approximately 4 yr, respectively. Larvae from 11 wolves, six black bears, and seven grizzly bears were genotyped. Six wolves were infected with T. nativa and five with Trichinella T6, four black bears were infected with T. nativa and two with Trichinella T6, and all seven grizzly bears were infected with Trichinella T6 and one of them had a coinfection with T. nativa. This is the first report of T. nativa in a grizzly bear from Canada. Bears have been linked to trichinellosis outbreaks in humans in Canada, and black bears are a subsistence food source for residents of the Dehcho region. In order to assess food safety risk it is important to monitor the prevalence of Trichinella spp. in both species of bear and their cohabiting mammalian food sources.     

Black Bear Reactions to Venomous and Non‐venomous Snakes in Eastern North America

Bears are often considered ecological equivalents of large primates, but the latter often respond with fear, avoidance, and alarm calls to snakes, both venomous and non‐venomous, there is sparse information on how bears respond to snakes. We videotaped or directly observed natural encounters between black bears (Ursus americanus) and snakes. Inside the range of venomous snakes in Arkansas and West Virginia, adolescent and adult black bears reacted fearfully in seven of seven encounters upon becoming aware of venomous and non‐venomous snakes; but in northern Michigan and Minnesota where venomous snakes have been absent for millennia, black bears showed little or no fear in four encounters with non‐venomous snakes of three species. The possible roles of experience and evolution in bear reactions to snakes and vice versa are discussed. In all areas studied, black bears had difficulty to recognize non‐moving snakes by smell or sight. Bears did not react until snakes moved in 11 of 12 encounters with non‐moving timber rattlesnakes (Crotalus horridus) and four species of harmless snakes. However, in additional tests in this study, bears were repulsed by garter snakes that had excreted pungent anal exudates, which may help explain the absence of snakes, both venomous and harmless, in bear diets reported to date.     

Why Lyme disease is common in the northern US,but rare in the south: The roles of host choice,host-seeking behavior,and tick density

Lyme disease is common in the northeastern United States, but rare in the southeast, even though the tick vector is found in both regions. Infection prevalence of Lyme spirochetes in host-seeking ticks, an important component to the risk of Lyme disease, is also high in the northeast and northern midwest, but declines sharply in the south. As ticks must acquire Lyme spirochetes from infected vertebrate hosts, the role of wildlife species composition on Lyme disease risk has been a topic of lively academic discussion. We compared tick–vertebrate host interactions using standardized sampling methods among 8 sites scattered throughout the eastern US. Geographical trends in diversity of tick hosts are gradual and do not match the sharp decline in prevalence at southern sites, but tick–host associations show a clear shift from mammals in the north to reptiles in the south. Tick infection prevalence declines north to south largely because of high tick infestation of efficient spirochete reservoir hosts (rodents and shrews) in the north but not in the south. Minimal infestation of small mammals in the south results from strong selective attachment to lizards such as skinks (which are inefficient reservoirs for Lyme spirochetes) in the southern states. Selective host choice, along with latitudinal differences in tick host-seeking behavior and variations in tick densities, explains the geographic pattern of Lyme disease in the eastern US.

Lyme disease is common in the northeastern United States, but rare in the southeast, even though the tick vector is found in both regions. This study shows that this is largely because the tick vectors attach abundantly to rodents (which are good hosts for the Lyme bacteria) in the north, and to lizards (which are relatively poor hosts for Lyme bacteria) in the south.     

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.     

A human case of tick bite by Ixodes nipponensis on the scalp

A human case of tick bite on the scalp was found at a local hospital on June, 1984. The patient, 63-year old female, was attacked by a tick while working in a farm forest which located in the suburbs of Seoul. The clinical complaint was a (worm) mass on the scalp which she thought as a tumor. On admission the patient complained of facial edema and general malaise. After removal of the mass (tick), small bleeding and discoloration were observed around the biting site. The tick was morphologically examined and identified as Ixodes nipponensis. This is the 4th human case of tick bite reported in the literature of Korea.     

云南高黎贡山国家级自然保护区保山片区周边社区人熊冲突现状

亚洲黑熊 (Ursus thibetanus) 与人类之间的冲突普遍存在。在高黎贡山国家级自然保护区周边社区,人熊冲突严重威胁了当地居民的生产生活和生命安全。因此研究人熊冲突现状是了解其发生机制并提出缓解冲突措施的基础。我们于2019年通过半结构式访谈法对高黎贡山保护区保山片区周边社区的79位居民进行了人熊冲突相关的调查。结果表明亚洲黑熊在高黎贡山保护区周边社区的肇事类型按发生频率由高到低依次为破坏农作物 (119起)、捕食家畜 (43起)、损害蜂箱 (40起) 和伤人 (5起)。亚洲黑熊造成受访者经济损失最多的肇事类型是捕食家畜 (799 200元),之后依次为损害蜂箱 (309 300元) 和破坏农作物 (298 790元)。在高黎贡山保护区周边社区亚洲黑熊肇事的高峰期是每年的7—9月。在高黎贡山东西两侧亚洲黑熊肇事特征明显不同：东坡以破坏农作物为主,而损害蜂箱在西坡最常见。居住在高黎贡山西坡的村民比在东坡的村民对亚洲黑熊持有更为消极的态度,但消极的态度没有导致他们对黑熊进行报复性捕杀。此外,在高黎贡山周边社区72.0%的受访者表示没听说过当地有偷猎黑熊的事件,98.6%的受访者表示没听说过熊产品交易事件,大部分受访者表示在未来也没有使用熊产品的意愿。本文分析了高黎贡山保护区保山片区周边社区人熊冲突的现状,探讨了人熊冲突的空间和时间格局,为在高黎贡山开展缓解人熊冲突措施提供了科学依据。     

Bear historical ranges revisited: Documenting the increase of a once-extirpated population in Nevada

Black bears (Ursus americanus) were once abundant in Nevada and distributed throughout the state, yet recognition of the species' historical occurrence in the state is uncommon and has therefore been ignored in published distribution maps for North America. The lack of representation on distribution maps is likely due to the lack of any scientific data or research on bears in Nevada until 1987. Historical records dating back to the 1840s compiled by Nevada Department of Wildlife (NDOW) biologist Robert McQuivey indicate presence of black bears throughout the state in the 1800s through about 1930. The paucity of historical references after 1931 suggest extirpation of black bears from Nevada's interior mountain ranges by this time. We report on historical records of black bears in the state of Nevada and the results of a current population estimate of black bears derived from a sample of marked bears (n = 420) captured 707 times between 1997 and 2008. Using Pradel and Cormack–Jolly–Seber models in Program MARK, we estimated overall population size, finite rate of growth (λ = 1.16), quarterly and annual survival rates for males and females, seasonal capture probabilities, and recruitment rates. Our results indicate an overall population size of 262 ± 31 adult black bears in western Nevada. These results suggest that the once abundant, then extirpated population of black bears in Nevada is increasing at an annual average rate of 16%. Although the current distribution is limited to the western part of the state, our findings suggest possible expansion of the population into historical habitat within the interior and eastern portions of the state that have been absent of bears for >80 years. Finally, based on historical records, we present suggested revised historical distribution maps for black bears that include the Great Basin ranges in Nevada. © 2013 The Wildlife Society.     

Unraveling the mystery of the glacier bear: Genetic population structure of black bears (Ursus americanus) within the range of a rare pelage type

Glacier bears are a rare grey color morph of American black bear (Ursus americanus) found only in northern Southeast Alaska and a small portion of western Canada. We examine contemporary genetic population structure of black bears within the geographic extent of glacier bears and explore how this structure relates to pelage color and landscape features of a recently glaciated and highly fragmented landscape. We used existing radiocollar data to quantify black bear home‐range size within the geographic range of glacier bears. The mean home‐range size of female black bears in the study area was 13 km² (n = 11), whereas the home range of a single male was 86.9 km². We genotyped 284 bears using 21 microsatellites extracted from noninvasively collected hair as well as tissue samples from harvested bears. We found ten populations of black bears in the study area, including several new populations not previously identified, divided largely by geographic features such as glaciers and marine fjords. Glacier bears were assigned to four populations found on the north and east side of Lynn Canal and the north and west side of Glacier Bay with a curious absence in the nonglaciated peninsula between. Lack of genetic relatedness and geographic continuity between black bear populations containing glacier bears suggest a possible unsampled population or an association with ice fields. Further investigation is needed to determine the genetic basis and the adaptive and evolutionary significance of the glacier bear color morph to help focus black bear conservation management to maximize and preserve genetic diversity.     

Population-level resource selection by sympatric brown and American black bears in Alaska

Distribution theory predicts that for two species living in sympatry, the subordinate species would be constrained from using the most suitable resources (e.g., habitat), resulting in its use of less suitable habitat and spatial segregation between species. We used negative binomial generalized linear mixed models with fixed effects to estimate seasonal population-level resource selection at two spatial resolutions for female brown bears (Ursus arctos) and female American black bears (U. americanus) in southcentral Alaska during May–September 2000. Black bears selected areas occupied by brown bears during spring which may be related to spatially restricted (i.e., restricted to low elevations) but dispersed or patchy availability of food. In contrast, black bears avoided areas occupied by brown bears during summer. Brown bears selected areas near salmon streams during summer, presumably to access spawning salmon. Use of areas with high berry production by black bears during summer appeared in response to avoidance of areas containing brown bears. Berries likely provided black bears a less nutritious, but adequate food source. We suggest that during summer, black bears were displaced by brown bears, which supports distribution theory in that black bears appeared to be partially constrained from areas containing salmon, resulting in their use of areas containing less nutritious forage. Spatial segregation of brown and American black bears apparently occurs when high-quality resources are spatially restricted and alternate resources are available to the subordinate species. This and previous work suggest that individual interactions between species can result in seasonal population-level responses.     

Abundance,genetic diversity and conservation of Louisiana black bears (<Emphasis Type="Italic">Ursus americanus luteolus</Emphasis>) as detected through noninvasive sampling

Although the Louisiana black bear (Ursus americanus luteolus) is currently listed as threatened under the Endangered Species Act, there have been no attempts to estimate range-wide abundance. This subspecies was thought to occupy a near contiguous range across southern Mississippi, Louisiana and east Texas but is now restricted to three isolated areas in Louisiana. In 1964, Louisiana initiated a restocking program in which black bears from Minnesota were introduced into two of these areas. It is not clear how the additions affected population structure or if substantial breeding occurred between native and introduced bears. Using baited sites to snare hair samples, and microsatellite DNA analysis to distinguish individuals, we estimated abundance of two geographically isolated bear populations in south central Louisiana: Inland and Coastal. Additionally, we examined genetic variation both within and between the two populations. Mark recapture analysis of the distribution of individual captures during two primary sampling periods resulted in population estimates of 77 ± 9 for Coastal and 41 ± 6 for Inland. Genetic analysis revealed significant population differentiation (F _ST = 0.206) between the two populations. The apparently smaller Inland population exhibited more diversity than the Coastal, which suggests that the genetic structure of the Inland population has been influenced by the reintroduction. Both of these populations are isolated and face considerable demographic and genetic threats, thus conservation measures to protect both are warranted. However, the Coastal population is more representative of Louisiana black bears prior to reintroduction and special consideration should be given to insure its integrity.     

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.     

Distinguishing Asiatic Black Bears and Sun Bears by Claw Marks on Climbed Trees

Abstract: Asiatic black bears (Ursus thibetanus) and sun bears (Helarctos malayanus) are sympatric in mainland Southeast Asia and face similar threats of habitat loss and commercial poaching. They are rarely seen but leave distinct signs, especially claw marks on climbed trees. These markings, which are potentially valuable indicators of presence, population status, and behavior of black bears and sun bears, have limited usefulness if the 2 species cannot be differentiated. We measured 121 claw mark imprints on climbed trees from 43 known (mainly captive) individual black bears and sun bears of both sexes in Thailand and Cambodia. The span across the markings made by 3, 4, or 5 claws from the hind foot was significantly greater for black bears than sun bears. We developed discriminant function models with these variables and arranged them in a 3-step process that distinguished claw marks as either sun bear, black bear, or indeterminate. This procedure correctly classified 95% of claw marks from the experimental animals. Tested on wild bears (at sites where only one species occurred), the procedure correctly classified 91% of claw marks of black bears in China (n = 94) and 100% of claw marks of sun bears in Indonesia (n = 32). The main limitation of the method was in distinguishing young, small black bears (cubs and yearlings) from sun bears. Nevertheless, application of these findings will be valuable in bear research and monitoring programs throughout Southeast Asia, where sign surveys have, until now, been hampered by the inability to differentiate these 2 ecologically and behaviorally similar species. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):814–821; 2008)     

Influence of Campsites on Black Bear Habitat Use and Potential Impact on Caribou Restoration

Ursus americanus(black bear) predation could limit the success of the proposed restoration of Rangifer tarandus (woodland caribou) to Minnesota. The problem was recently identified as a major factor in the failure of a similar restoration effort in Maine. During the summer of 1991 we conducted a survey in the region of the proposed restoration, using bait stations to identify bear presence. Four settings were sampled: islands with campsites, islands without campsites, mainland areas with campsites, and mainland areas without campsites. Results from the survey suggest that black bears use areas with campsites more than those without. Whereas caribou may use islands preferentially for calving to escape predation, islands with campsites may be unfavorable for caribou calf survival due to frequent bear visitation.