The American black bear (Ursus americanus) is recolonizing in Mississippi, which may positively or negatively impact people. Therefore, it is important to understand the acceptance capacity and intentions of people to accept black bears. We used a self-administered mail survey of 4080 Mississippi landowners in ‘frequent black bear encounter counties’ and ‘infrequent black bear encounter counties’ to assess their intention to accept black bears. Based on the 1266 returned surveys, we found perceived behavioral control was the strongest determinant of landowners' intention to accept black bears, followed by their attitudes towards black bears. In addition, landowners' social trust in the state wildlife agency was instrumental in determining their intention to accept black bears. Landowners who have higher social trust, lower perceived risks, and higher perceived benefits were more likely to accept black bears. Overall, the weighted least square means and variance adjusted model explained about 70% of the variation in acceptance, and the determinants influencing the intention to accept black bears remained consistent across the two county categories. Local management strategies need to be employed to educate landowners on black bear ecology, risk mitigation measures, and approaches to maximize appreciation of black bears.
American black bears (Ursus americanus) in the Lower Mississippi Alluvial Valley (LMAV) suffered significant declines in the 20th century from habitat loss and overexploitation. Remnant black bear subpopulations in southeastern Arkansas and eastern Louisiana have recovered and expanded into western Mississippi in the early 2000s. However, the genetic status and origin of subpopulations in Mississippi remain poorly understood. We evaluated genetic diversity, population structure, and connectivity of black bears in the LMAV and compared our results to a previous study. We identified an expanded admixture zone in western Mississippi where black bears dispersing from Arkansas and Louisiana converged and reproduced. The subpopulation in southern Mississippi exhibited the highest allelic richness (AR = 4.50) and elevated expected heterozygosity (HE = 0.61), consistent with recent admixture. Gene flow was greatest from the Tensas River Basin in Louisiana to the Mississippi subpopulations and to the Three Rivers Complex in Louisiana (m = 0.17–0.22), suggesting corridors between Mississippi and Louisiana may be similar in quality to corridors among Louisiana subpopulations. However, dispersal into Arkansas from all subpopulations remained limited, underscoring the genetic isolation of the White River Basin and West Gulf Coastal Plain subpopulations. Our results revealed an undocumented dispersal pathway from Louisiana’s Upper Atchafalaya River Basin into southern Mississippi. Despite these promising findings, genetic diversity in Mississippi and the LMAV remains lower than in many other black bear populations. Continued habitat restoration, improved corridor connectivity, and ongoing genetic monitoring are essential to support black bear recovery in Mississippi and across the LMAV.
Savannas depend on frequent, low-intensity fires that shape animal and plant communities. These fires alter animal populations, movement, and habitat use. Here, we report on how fires in a longleaf pine (Pinus palustris) savanna affected small mammal microhabitat use via changes in competition and predation. We monitored small mammal populations and vegetation subjected to biennial prescribed fires and compared microhabitat use of three small mammal populations [hispid cotton rats (Sigmodon hispidus), cotton mice (Peromyscus gossypinus) and oldfield mice (Peromyscus polionotus)] in the presence and absence of mesocarnivores while accounting for changes in density and movement of each small mammal species. Densities of cotton rats varied greatly across years but were similar between predator exclosures and controls. However, frequency of use was greater in exclosures than in controls irrespective of vegetation characteristics, suggesting predation risk altered cotton rat microhabitat use. Conversely, higher relative abundance of cotton rats was associated with lower cotton mouse and oldfield mouse use, suggesting spatial separation in niche and indicating that cotton mice expand their realized niche following predation-induced declines of cotton rats associated with prescribed burn events. Our results contribute to a better understanding of pyrodiversity and how interspecific interactions can moderate effects of vegetation changes following prescribed fires.
Abstract Close‐kin mark–recapture (CKMR) methods use information on genetic relatedness among individuals to estimate demographic parameters. An individual's genotype can be considered a ‘recapture’ of each of its parent's genotype, and the frequency of kin‐pair matches detected in a population sample can directly inform estimates of abundance. CKMR inference procedures require analysts to define kinship probabilities in functional forms, which inevitably involve simplifying assumptions. Among others, population structure can have a strong influence on how kinship probabilities are formulated. Many terrestrial species are philopatric or face barriers to dispersal, and not accounting for dispersal limitation in kinship probabilities, can create substantial bias if sampling is also spatially structured (e.g. via harvest). We present a spatially explicit formulation of CKMR that corrects for incomplete mixing by incorporating natal dispersal distances and spatial distribution of individuals into the kinship probabilities. We used individual‐based simulations to evaluate the accuracy of abundance estimates obtained with one spatially naïve and two spatially explicit CKMR models across six scenarios with distinct spatial patterns of relative abundance and sampling probability. Estimates of abundance obtained with a CKMR model naïve to spatial structure were negatively biased when sampling was spatially biased. Incorporating patterns of natal dispersal in the kinship probabilities helped address this bias, but estimates were not always accurate depending on the model used and the scenario considered. Incorporating natal dispersal into spatially structured CKMR models can address the bias created by population structure and heterogeneous sampling but will often require additional assumptions and auxiliary data (e.g. relative abundance indices). The models shown here were designed for terrestrial species with continuous patterns of natal dispersal and high year‐to‐year site fidelity but could be extended to other species.
1. Weasels (genus Mustela and Neogale) are of management concern as declining native species in some regions and invasive species in others. Regardless of the need to conserve or remove weasels, there is increasingly a need to use non-invasive monitoring methods to assess population trends.2. We conducted a literature review and held the first ever International Weasel Monitoring Symposium to synthesise information on historical and current non-invasive monitoring techniques for weasels. We also explored current limitations, opportunities, and areas of development to guide future research and long-term monitoring.3. Our literature search revealed that in the past 20 years, camera traps were the most commonly used non-invasive monitoring method (62% of studies), followed by track plates or scent stations designed to collect footprints (23%) and walking transects for tracks in snow or soil (8.7%).4. Experts agreed that the most promising non-invasive monitoring techniques available include use of citizen scientist reporting, detection dogs, detecting tracks, non-invasive genetic surveys, and enclosed or unenclosed camera trap systems. Because each technique has benefits and limitations, using a multi-method approach is likely required.5. There is a need for strong commitment to dedicated monitoring that is replicated over space and time such that trend data can be ascertained to better inform future management action. The diversity of non-invasive monitoring methods now available makes such monitoring possible with relatively minor commitments of funding and effort.
American black bear (Ursus americanus) populations are increasing throughout much of North America. Use of multiple harvest methods, including hunting over bait, is intended to increase harvest success rates to meet harvest and population management objectives. However, black bear population growth can be influenced by food availability, and some speculate the use of bait may inadvertently increase bear abundance through food resource supplementation. We collected hair from black bears captured from 2005-2019 and a selection of potential food items, including those used as bait from 3 study areas in Maine, USA, with different levels of human influence. We used stable isotope analysis of the black bear hair and food item samples to evaluate the contribution of different identified food groups to the diet of individual bears. We found no evidence that greater contribution of human food resources, including bait, increased the number of cubs per litter for reproductive females or that human foods comprised a greater part of the diet in years when natural food resources were less abundant. Approximately 69% of black bear harvest occurred over bait. We found the probability of reproductive-age females to be harvested increased with average representation of human foods with high carbon enrichment (including bait) in their diet, but the relationship was weak, likely because of sampling constraints. Additionally, the probability of being harvested was greater in years when natural food resources were scarce. We conclude that bait is not available on the landscape in large enough amounts or for a sufficient amount of time in Maine to substantially influence female reproduction. Our results indicate hunting over bait is an effective tool in a state that is attempting to maintain a stable bear population via harvest, and dispels conjecture that hunting over bait may increase cub production and offset the intention of harvest.
Close-kin mark-recapture (CKMR) is a method analogous to traditional mark-recapture but without requiring recapture of individuals. Instead, multilocus genotypes (genetic marks) are used to identify related individuals in one or more sampling occasions, which enables the opportunistic use of samples from harvested wildlife. To apply the method accurately, it is important to build appropriate CKMR models that do not violate assumptions linked to the species' and population's biology and sampling methods. In this study, we evaluated the implications of fitting overly simplistic CKMR models to populations with complex reproductive success dynamics or selective sampling. We used forward-in-time, individual-based simulations to evaluate the accuracy and precision of CKMR abundance and survival estimates in species with different longevities, mating systems, and sampling strategies. Simulated populations approximated a range of life histories among game species of North America with lethal sampling to evaluate the potential of using harvested samples to estimate population size. Our simulations show that CKMR can yield nontrivial biases in both survival and abundance estimates, unless influential life history traits and selective sampling are explicitly accounted for in the modeling framework. The number of kin pairs observed in the sample, in combination with the type of kinship used in the model (parent-offspring pairs and/or half-sibling pairs), can affect the precision and/or accuracy of the estimates. CKMR is a promising method that will likely see an increasing number of applications in the field as costs of genetic analysis continue to decline. Our work highlights the importance of applying population-specific CKMR models that consider relevant demographic parameters, individual covariates, and the protocol through which individuals were sampled.
AIMS Assess bacterial community changes over time in soybean (Glycine max) crop fields following cover crop (CC) and no-till (NT) implementation under natural abiotic stressors. METHOD AND RESULTS Soil bacterial community composition was obtained by amplifying, sequencing and analyzing the V4 region of the 16S rRNA gene. Generalized linear mixed models were used to assess the effects of tillage, CC and time on bacterial community response. The most abundant phyla present were Acidobacteria, Actinobacteria, Bacteroidetes, and Verrucomicrobia. Bacterial diversity increased in periods with abundant water. Reduced tillage (RT) increased overall bacterial diversity, but NT with a CC was not significantly different than RT treatments under drought conditions. Cover crops shifted abundances of Firmicutes and Bacteroidetes depending on abiotic conditions. CONCLUSIONS In the Lower Mississippi Alluvial Valley (LMAV), USA, NT practices lower diversity and influence long-term community changes while cover crops enact a seasonal response to environmental conditions. No-till and RT management affect soil bacterial communities differently than found in other regions of the country.
Within dynamic ecosystems, research into how land use changes and patterns affect species diversity has led to a suite of ecological hypotheses to assess species-landscape associations. The Habitat Amount Hypothesis suggests that it is the total amount of habitat, regardless of configuration, whereas the Multi-dimensional Hypothesis suggests it is the suite of local, landscape, and landform characteristics that have the greatest influence on species diversity within its local landscape. Our study aims to understand how landscape pattern influences species abundance, in the context of these two competing hypotheses on priority avian species in working forest landscapes of the southeastern United States. To examine these hypotheses, we conducted bird point counts and vegetation surveys in short-rotation loblolly pine (Pinus taeda) forests in east-central Mississippi during 2019–2020 and used abundance and richness models to assess avian species associations to amount vs. configuration of habitat in a 2 km2 landscape. We found that habitat amount alone did not exhibit consistent positive associations with species abundance for both early-successional and mature forest associated avian communities. Most target species exhibited positive associations with patch proximity, measured by Euclidean distance, and proximity-area index. However, measures of species richness showed no association with amount or proximity. Associations with landform features generally had positive influences on early-successional species than mature-pine priority species. The dynamic mosaic of forest stand ages may be sufficient in providing habitat needs such that measures of richness are not driven by amount and proximity at the 2 km2 scale in this working landscape. However, influences of proximity and landform on priority species abundance warrant further research to assess potential drivers of associations with stand proximity and effects of amount and proximity on measures of species diversity across scales. Given the growing demand for forest products, sustainable forestry guidelines that consider proximity of stands in similar age classifications could enhance landscape suitability for some target species.
Social living provides benefits to group members, but these benefits come at a cost. In fission–fusion societies, individuals or small groups leave and join different groups as ecological constraints on group size fluctuate. Little research has been conducted on how human disturbance influences fission–fusion groups after accounting for ecological conditions. As a large, wide-ranging species with large resource needs facing increasing human disturbance (e.g. poaching and habitat loss), African forest elephants, Loxodonta cyclotis, provide unique insight into how environmental, social and anthropogenic factors influence group size. We reconstructed forest elephant social groups using noninvasive genetic samples extracted from elephant dung collected while tracking GPS-collared forest elephants. Through a novel application of hierarchical mark–recapture models, we estimated group size and the anthropogenic, demographic and environmental factors associated with fluctuations in group size. We found that high fruit availability was associated with a decrease in group size and that human disturbance (measured as an index of the global human footprint) was associated with an increase in group size, but to a lesser degree. Understanding social group dynamics is important for ensuring effective population management of forest elephants, both for tracking when large groups might be at risk from poaching and preventing the negative health associations of suboptimal group sizes such as increased stress and decreased reproduction. Additionally, our integration of genotyping, satellite remote sensing and statistical methods can inform the study of forest elephants and other cryptic species into the future.
Comprehensive disease surveillance has not been conducted in elk (Cervus canadensis) in Tennessee, US, since their reintroduction to the state 20 yr ago. We identified causes of death, estimated annual survival, and identified pathogens of concern in elk at the North Cumberland Wildlife Management Area (NCWMA), Tennessee, US. In 2019 and 2020, we captured 29 elk (21 females, eight males) using chemical immobilization and fitted individuals with GPS collars with mortality sensors. Elk that died between February 2019 and February 2022 were necropsied to identify causes of death; these included disease associated with meningeal worm (Parelaphostrongylus tenuis; n=3), poaching (n=1), vehicular collision (n=1), legal hunter harvest (n=1), and unknown due to carcass degradation (n=3). Using data from GPS collars and known-fate survival models, we estimated an average yearly survival rate of 80.2%, indicating that survival had not significantly increased from soon after elk reintroduction (79.9%). We collected blood, tissue, feces, and ectoparasites opportunistically from anesthetized elk for health surveillance. We identified lone star ticks (Amblyomma americanum; n=53, 85.5%; 95% confidence interval [CI], 73.72-92.75), American dog ticks (Dermacentor variabilis; n=8, 12.9%; 95% CI, 6.13-24.40), and black-legged ticks (Ixodes scapularis; n=1, 1.6%; 95% CI, 0.08-9.83). We detected evidence of exposure to Anaplasma marginale (100%; 95% CI, 84.50-100.00), Leptospira interrogans (70.4%; 95% CI, 49.66-85.50), Toxoplasma gondii (55.6%; 95% CI, 35.64-73.96), epizootic hemorrhagic disease virus (51.9%; 95% CI, 32.35-70.84), and Theileria cervi (25.9%; 95% CI, 11.78-46.59). Johne's disease (Mycobacterium avium subsp. paratuberculosis) is potentially established within the population, but has not been previously documented in eastern elk populations. Disease associated with P. tenuis was a primary cause of death, and more research is needed to understand its ecology and epidemiology. Research to determine population implications of other detected pathogens at the NCWMA is warranted.
There is a need to achieve sustainable agricultural production to secure food, fiber, and fuel for a growing global population. Climate-smart (CS) actions (no-till and cover crops) can reduce carbon emissions and promote soil organic carbon (SOC) storage. Contemporary voluntary carbon markets provide producers with a monetary incentive to adopt CS actions. However, SOC–yield dynamics under CS actions are not well known, making it difficult for producers to judge whether additional income from carbon credits will offset potential losses to yield income. We designed a SOC–yield framework that captures SOC–yield–income dynamics under traditional (reduced tillage, no cover crops) and CS actions. Using a modified structured decision-making approach, we applied the framework to a case study in which producers aim to increase income by selling carbon credits after adopting CS actions. Specifically, we demonstrated how to balance tradeoffs between yield and carbon credit income that arise from tillage and winter cover crop actions (cereal rye, Secale cereale L. and crimson clover, Trifolium incarnatum L.) in a soybean (Glycine max L.) production system in Mississippi. Results indicated that a producer could minimize losses to net yield income by adopting no-till if already using cover crops. There was also evidence that carbon credit income could offset losses to yield income when adopting CS in place of traditional actions. Identifying risks to yield income and SOC storage can help design carbon neutrality policies that have minimum impact on a producer’s income. History: This paper has been accepted for the Decision Analysis Special Issue on Decision Analysis to Advance Environmental Sustainability. Funding: This work was supported by the USDA-ARS [Grants 58-0200-0-002 (Advancing Agricultural Research) and 58-6001-8-003] and the USDA National Institute of Food and Agriculture [McIntire Stennis Project 1020959]. Supplemental Material: The online appendix is available at https://doi.org/10.1287/deca.2023.0478 .
Species coexistence is governed by availability of resources and intraguild interactions including strategies to reduce ecological overlap. Gray foxes are dietary generalist mesopredators expected to benefit from anthropogenic disturbance, but populations have declined across the midwestern USA, including severe local extirpation rates coinciding with high coyote and domestic dog occurrence and low red fox occurrence. We used data from a large-scale camera trap survey in southern Illinois, USA to quantify intraguild spatial and temporal interactions among the canid guild including domestic dogs. We used a two-species co-occurrence model to make pairwise assessments of conditional occupancy and detection rates. We also estimated temporal activity overlap among species and fit a fixed-effects hierarchical community occupancy model with the four canid species. We partitioned the posterior distributions to compare gray fox occupancy probabilities conditional on estimated state of combinations of other species to assess support for hypothesized interactions. We found no evidence of broadscale avoidance among native canids and conclude that spatial and temporal segregation were limited by ubiquitous human disturbance. Mean guild richness was two canid species at a site and gray fox occupancy was greater when any combination of sympatric canids was also present, setting the stage for competitive exclusion over time. Domestic dogs may amplify competitive interactions by increasing canid guild size to the detriment of gray foxes. Our results suggest that while human activities can benefit some mesopredators, other species such as gray foxes may serve as bellwethers for habitat degradation with trophic downgrading and continued anthropogenic homogenization.
Populations of bears in Asia are vulnerable to extinction and effective monitoring is critical to measure and direct conservation efforts. Population abundance (local density) or growth (λ) are the most sensitive metrics to change. We discuss the value in implementing spatially explicit capture-recapture (SCR), the current gold standard for density estimation, and open population SCR (OPSCR) to monitor changes in density over time. We provide guidance for designing studies to provide estimates with sufficient power to detect changes. Because of the wide availability of camera traps and interest in their use, we consider six density estimation methods and their extensions developed for use with camera traps, with specific consideration of assumptions and applications for monitoring Asian bears. We conducted a power analysis to calculate the precision in estimates needed to detect changes in populations with reference to IUCN Red List criteria. We performed a systematic review of empirical studies implementing camera trap abundance estimation methods and considered sample sizes, effort, and model assumptions required to achieve adequate precision for population monitoring. We found SCR and OPSCR, reliant on “marked” individuals, are currently the only methods with enough power to reliably detect even moderate to major (20–80%) declines. Camera trap methods with unmarked individuals rarely achieved precision sufficient to detect even large declines (80–90%), although with some exceptions (e.g., situations with moderate population densities, large number of sampling sites, or inclusion of ancillary local telemetry data. We describe additional estimation options including line transects, direct observations, monitoring age-specific survival and reproductive rates, and hybrid/integrated methodologies that may have potential to work for some Asian bear populations. We conclude monitoring changes in abundance or density is possible for most Asian bear populations but will require collaboration among researchers over broad spatial extents and extensive financial investment to overcome biological and logistical constraints. We strongly encourage practitioners to consider study design and sampling effort required to meet objectives by conducting simulations, power analyses, and assumption checks prior to implementing monitoring efforts, and reporting standardized dispersion measures such as coefficients of variation to allow for assessment of precision. Our guidance is relevant to other low-density and wide-ranging species.
Sperm cryopreservation is a crucial tool in amphibian assisted reproductive technologies that aids in population and genetic management of at-risk species. Using Anaxyrus fowleri as a model species, this study found that fertilization success and embryonic development are dependent on the cryoprotectant and freezing rate applied to sperm during cryopreservation.
Designing a population monitoring program for Asian bears presents challenges associated with their low densities and detectability, generally large home ranges, and logistical or resource constraints. The use of an occupancy-based method to monitor bear populations can be appropriate under certain conditions given the mechanistic relationship between occupancy and abundance. The form of the occupancy–abundance relationship is dependent on species-specific characteristics such as home range size and population density, as well as study area size. To assess the statistical power of tests to detect population change of Asian bears, we conducted a study using a range of scenarios by simulating spatially explicit individual-based capture-recapture data from a demographically open model. Simulations assessed the power to detect changes in population density via changes in site-level occupancy or abundance through time, estimated using a standard occupancy model or a Royle-Nichols model, both with point detectors (representing camera traps). We used IUCN Red List criteria as a guide in selection of two population decline scenarios (20% and 50%), but we chose a shorter time horizon (10 years = 1 bear generation), meaning that declines were steeper than used for IUCN criteria (3 generations). Our simulations detected population declines of 50% with high power (>0.80) and low false positive rates (FPR: incorrectly detecting a decline) (<0.10) when detectors were spaced at > 0.67 times the home range diameter (home-range spacing ratio: HRSR, a measure of spatial correlation), such that bears would tend to overlap no more than two detectors. There was high (0.85) correlation between realized occupancy and N in these scenarios. The FPR increased as the HRSR decreased because of spatial correlation in the occupancy process induced when individual home ranges overlap multiple detectors. The mean statistical power to detect more gradual population declines (20% in 10 years) with HRSR > 0.67 was low for occupancy models 0.22 (maximum power 0.67) and Royle-Nichols models (0.24; maximum power 0.67), suggesting that declines of this magnitude may not be described reliably with 10 years of monitoring. Our results demonstrated that under many realistic scenarios that we explored, false positive rates were unacceptably high. We highlight that when designing occupancy studies, the spacing between point detectors be at least 0.67 times the diameter of the home range size of the larger sex (e.g., males) when the assumptions of the spatial capture-recapture model used for simulation are met.
Many wildlife species are threatened in Asia, including the five species of terrestrial bears (Asiatic black, Ursus thibetanus; brown, U. arctos; sloth, Melursus ursinus; sun, Helarctos malayanus; giant panda, Ailuropoda melanoleuca): many populations of these bears are thought to be declining or imperiled by small population size. Here our aim is to document how population assessments have been conducted for bears in Asia. We searched the literature and identified 102 studies published during 1999–2021 that investigated the status of an Asian bear population; these occurred in 24 of the 32 bear range countries in Asia. At the most basic level, 11% of studies verified presence of bears in places where they were not known to exist. The most common objective (53% of papers) was a distribution map, often derived from presence locations in a habitat-based model. Occupancy studies (15%) used temporal (time stamps on images from cameras) or spatial (transect segments) replicates, but tended to focus on “use”, so detector spacing was sometimes not appropriate for occupancy. Purported population indices, such as sign density or camera trap encounter rates, were reported in 16% of studies. One third of studies provided a population estimate, but only 10 studies in two decades used a rigorous method (e.g., mark–recapture). Sign surveys and interviews were the most common methods for determining bear presence, and local interviews were heavily relied upon for assessing population trend. Camera trapping has become increasingly prevalent, but only one study obtained a population estimate using photographs to distinguish natural individual markings. Only three studies used hair traps to obtain DNA-based population estimates, and three other studies obtained population estimates from DNA in scats. Just three studies quantitatively measured change in population size or occupancy over time, and none of these showed a decline. Unique rangewide sign surveys of giant pandas showed significant geographic expansion. The opinions of experts and local people, now heavily relied upon for population assessments, are not reliable or sensitive enough for monitoring. Quantitative population assessments are desirable to direct conservation actions toward the most perilous situations, and provide a means to gauge the effectiveness of conservation actions. This paper demonstrates the paucity of rigorous monitoring of Asian bears, and leads off a series of papers that propose improved methods for assessing distribution, occupancy, and density.
The transition of natural landscapes to agricultural uses has resulted in severe loss of soil organic carbon, significantly contributing to CO2 emissions and rising global temperatures. However, soil has the largest store of terrestrial carbon (C), a considerable sink and effective strategy for climate change mitigation if managed properly. Cover crops (CC) and no-till (NT) management are two management strategies that are known to increase percent organic carbon (%OC); however, adoption of these practices has been low in the mid-South due to lack of region-specific research and resistance to unproven practices. Therefore, the purpose of this study was to evaluate the impacts of CC-NT treatments in soybean cropping systems on soil percent organic carbon (%OC) and CO2 flux following long-term implementation. Results showed significantly greater %OC in NT (1.27% ± 0.03) than reduced till (RT; 1.10% ± 0.03; p < 0.001) and greater in both CC (rye: 1.23% ± 0.03, rye + clover: 1.22% ± 0.03) than no cover (1.11% ± 0.03; p < 0.001). Bacterial abundance (p = 0.005) and pH (p = 0.006) were significant predictors of %OC. There was no overall significant difference in CO2 flux between tillage or CC treatments; however, there were significant differences between NT and RT in July of 2020 when %RH increased (p < 0.001). Bacterial abundance negatively impacted CO2 flux (p < 0.05), which contradicts most studies. The rate of proportional change and pattern of variability in C pools suggested loss of %OC in RT treatments that were not apparent when considering %OC alone. The results of this study provide valuable insight into C turnover and the effectiveness of CC use in the Mid-South to increase soil C stocks.
Changes in the distribution of a species can be used to as a metric of conservation status and to identify the loss or gain of isolated populations. This mapping process is a primary tool of the IUCN SSC Red List assessment. Most distribution maps are based on expert opinion or species distribution models based on a combination of species detection records and known habitat and landscape affiliations for that species. However, modeling the distribution for some species is difficult due to low levels of sampling, low detectability, and loose or uncertain associations with landscape attributes. These issues may be particularly prevalent for Asian bears that have generalist habitat requirements and are heavily poached across their range. Presently the range of all bear species in Asia is delineated primarily using expert opinion. Members of the IUCN SSC Bear Specialist Group attempted to create a rule set to combine current detections with known habitat and home range preferences to improve distribution maps for the purpose of conservation metrics and monitoring. The results of applying this rule set for giant pandas (Ailuropoda melanoleuca) closely matched the current IUCN mapped range, but the results for Asiatic black bears (Ursus thibetanus) did not corroborate the IUCN map based solely on expert opinion. We present a list of recommended actions for improving distribution mapping for bears in Asia and possibly any species whose current distribution is heavily influenced by poorly measured metrics such as poaching.
Information about population demography is crucial for developing and implementing conservation measures. The brown bear in the Gobi desert of southwestern Mongolia (referred to as the Gobi bear) is one of the smallest and most isolated brown bear populations in the world. We conducted genetic sampling (n = 2660 samples collected) using hair corrals around feeding sites at 13 water sources during 2009, 2013, and 2017 to evaluate population size, survival, and population trend. Bears were identified using 13 microsatellite loci and one sex marker. We detected 51 unique individuals (15F and 36M) from our targeted surveys in 2009, 2013, and 2017. Based on capture-mark-recapture robust design, population estimates were 23 (95% CI: 21-32) in 2009, 28 (95% CI: 25-35) in 2013, and 31 (95% CI: 29-38) individuals in 2017. Spatial capture-recapture analysis suggested abundance was very low (N<^> = 27; 95% CI: 22-35), and there was no significant change from 2009 to 2017. The population density was 0.93 bears/1000 km(2) (95% CI: 0.74-1.17). Our population estimates suggested a stable population trend. However, the population is still very small, and the sex ratio is skewed toward males, raising concerns for future persistence. Annual survival based on Robust design CMR was 0.85. Low abundance and apparent survival for both sexes in this unhunted population coupled with a skewed sex ratio highlight the need for on-the-ground conservation action to conserve this isolated population of bears.