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American Black Bear

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David L. Garshelis – One of the best experts on this subject based on the ideXlab platform.

  • delineating the ecological and geographic edge of an opportunist the American Black Bear exploiting an agricultural landscape
    Ecological Modelling, 2018
    Co-Authors: Mark A Ditmer, David L. Garshelis, Karen V Noyce, John R Fieberg


    Abstract Determining habitat requirements for the persistence of a wildlife population is especially difficult for wide-ranging, opportunist species. The American Black Bear (Ursus Americanus) is one such species that is re-colonizing parts of its former range and colonizing new geographic regions. We sought to predict the potential for further westward expansion of a population of Black Bears that has recently colonized a primarily agricultural (>50%) landscape with small fragmented islands of forest (∼17%) at the edge of its range in northwestern Minnesota. We delineated critical aspects of Bears’ spatial ecology by examining size and habitat composition of home ranges of GPS-collared individuals (n = 38; 75 Bear-years; 2007–2013) at both annual and weekly temporal scales. We measured food production by habitat type, and used a moving window equivalent to a weekly home range (WHR) to quantify and map habitat suitability across the region, considering temporal variations in observed natural forage availability. Male Bears used expansive home ranges on an annual basis (largest recorded for this species; 95% KDE h-ref: X ¯  = 834 km2, 95% CI = 596–1072 km2); females traveled less, but still had relatively large home ranges (95% KDE h-ref: X ¯  = 91 km2, 95% CI = 55–128 km2). Summer and fall WHRs contracted when they included higher percentages of oak forest or crop cover (key foods), and expanded with a higher density of roads and higher percentage of non-consumable agriculture and wetlands (i.e., unused areas embedded in the home range). Caloric density had the strongest negative influence on WHR size. We predict males can expand farther westward by virtue of their adaptable, sprawling home ranges that can encompass an array of resources, and their inclination to tolerate and exploit landscapes with few other Bears and patchy vegetative cover, embedded with agriculture, roads, and people. Females are more limited to woodlots with natural foods and less apt to be located in open treeless expanses. However, we observed wide year-to-year variations in food production and found that during the most favorable conditions, females could be enticed farther westward, although it is unclear whether they would settle in an environment with even less tree cover than in the current extremity of their range.

  • seasonal regulation of the growth hormone insulin like growth factor i axis in the American Black Bear ursus Americanus
    American Journal of Physiology-endocrinology and Metabolism, 2011
    Co-Authors: Stanley Blumenthal, Ralph A. Nelson, David L. Garshelis, Rebecca Morganboyd, Mary Turyk, Terry G Unterman


    The American Black Bear maintains lean body mass for months without food during winter denning. We asked whether changes in the growth hormone/insulin-like growth factor-I (GH-IGF-I) axis may contr…

  • Sex steroid and prolactin profiles in male American Black Bears (Ursus Americanus) during denning.
    Journal of Veterinary Medical Science, 1999
    Co-Authors: Toshio Tsubota, Ralph A. Nelson, David L. Garshelis, Janice M Bahr


    Serum sex steroid and prolactin profiles were examined in the male American Black Bear, Ursus Americanus during denning. Sera collected in December and the following March from 8 denning male Black Bears in Minnesota, U.S.A. were assayed for testosterone, estradiol-17β and prolactin. Eight Bears were confirmed to be the denning mode based on a serum urea to creatinine ratio less than 10. Serum testosterone concentrations tended to increase from December to the subsequent March whereas serum estradiol-17β concentrations tended to decrease during this period. There were few changes in serum prolactin concentrations between December and March. These findings suggest that spermatogenesis and testicular steroidogenesis initiated during denning may be influenced by changes in serum sex steroid concentrations in the American Black Bear.

Jerrold L. Belant – One of the best experts on this subject based on the ideXlab platform.

  • Male use in female core areas and home ranges.
    , 2018
    Co-Authors: Cody D. Norton, Jerrold L. Belant, Nathan J. Svoboda, Dean E. Beyer, John G. Bruggink, Tyler R. Petroelje


    Relative probability of male American Black Bear use in core areas (50% kernel) and home ranges (95% kernel) of females with and without cubs, Upper Peninsula of Michigan, 2009–2011 and 2013–2014. Error bars represent 1 standard error.

  • Male use of available area.
    , 2018
    Co-Authors: Cody D. Norton, Jerrold L. Belant, Nathan J. Svoboda, Dean E. Beyer, John G. Bruggink, Tyler R. Petroelje


    Relative probability of male American Black Bear space use in Escanaba (2009–2011, 45.6°N, 87.4°W) and Crystal Falls (2013–2014, 46.3°N, 88.2°W) study areas during the breeding season, Upper Peninsula of Michigan.

  • Source populations and roads affect American Black Bear recolonization
    European Journal of Wildlife Research, 2015
    Co-Authors: Stephanie L. Simek, Jerrold L. Belant, Zhaofei Fan, Brad W. Young, Bruce D. Leopold, Jonathan P. Fleming, Brittany W. Waller


    Understanding species distributions and population responses to environmental parameters is important for addressing landscape-level species conservation. We assessed American Black Bear (Ursus Americanus) resource selection based on spatial distribution of a recolonizing population in Mississippi, USA. Given the philopatric behavior of female Bears and the risk-disturbance hypothesis, we predicted that Bears recolonizing Mississippi would occupy areas close to their source population but avoid areas near roads and with greater human population density. Using location data from radio-collared Black Bears, landscape metrics, and spatial autoregressive modeling, we estimated annual population-level space use. Our results confirm that Black Bears recolonizing Mississippi occupy habitats proximate to source populations and avoid areas near roads as probability of Bear use was greater in areas closer to source breeding populations and areas farther from roads. Land cover type, elevation, and human density did not influence Black Bear occurrence at the spatial resolution examined. The lack of avoidance to areas inhabited by humans was likely a consequence of overall low human density, legal protection afforded this species, and that proximity to source population likely has a greater effect on recolonization than avoidance of humans.

Joseph D Clark – One of the best experts on this subject based on the ideXlab platform.

  • early genetic outcomes of American Black Bear reintroductions in the central appalachians usa
    Ursus, 2019
    Co-Authors: Sean M. Murphy, Christopher W. Ryan, Ben C. Augustine, John T. Hast, Joseph D Clark, David W Weisrock, David M Kocka, Jaime L Sajecki, John J. Cox


    Habitat loss and overexploitation extirpated American Black Bears (Ursus Americanus) from most of the Central Appalachians, USA, by the early 20th Century. To attempt to restore Bears to the southwestern portion of this region, 2 reintroductions that used small founder groups (n = 27 and 55 Bears), but different release methods (hard vs. soft), were conducted during the 1990s. We collected hair samples from Black Bears during 2004–2016 in the reintroduced Big South Fork (BSF) and Kentucky–Virginia populations (KVP), their respective Great Smoky Mountains (GSM) and Shenandoah National Park (SNP) source populations, and a neighboring population in southern West Virginia (SWV) to investigate the early genetic outcomes of Bear reintroduction. Despite having undergone genetic bottlenecks, genetic diversity remained similar between reintroduced populations and their sources approximately 15 years after the founder events (ranges: AR = 4.86–5.61; HO = 0.67–0.75; HE = 0.65–0.71). Effective population sizes of the reintroduced KVP and BSF (NE = 31 and 36, respectively) were substantially smaller than their respective SNP and GSM sources (NE = 119 and 156, respectively), supporting founder effects. Genetic structure analysis indicated that the hard-released (i.e., no acclimation period) KVP founder group likely declined considerably, whereas the soft-released BSF founder group remained mostly intact, suggesting superior effectiveness of soft releases. Asymmetrical gene flow via immigration from the SWV has resulted in the KVP recovering from the initial founder group reduction. Sustained isolation, small NE, and small population size of the BSF may warrant continued genetic monitoring to determine if gene flow from neighboring populations is established or NE declines. For future Bear reintroductions, we suggest managers consider sourcing founders from populations with high genetic diversity and soft-releasing Bears to locales that are, if possible, within the dispersal capability of extant populations to mitigate the potential consequences of founder effects and isolation.

  • effects of sampling conditions on dna based estimates of American Black Bear abundance
    Journal of Wildlife Management, 2013
    Co-Authors: Jared S. Laufenberg, Frank T Van Manen, Joseph D Clark


    DNA-based capture-mark-recapture techniques are commonly used to estimate American Black Bear (Ursus Americanus) population abundance (N). Although the technique is well established, many questions remain regarding study design. In particular, relationships among N, capture probability of heterogeneity mixtures A and B (pA and pB, respectively, or , collectively), the proportion of each mixture (π), number of capture occasions (k), and probability of obtaining reliable estimates of N are not fully understood. We investigated these relationships using 1) an empirical dataset of DNA samples for which true N was unknown and 2) simulated datasets with known properties that represented a broader array of sampling conditions. For the empirical data analysis, we used the full closed population with heterogeneity data type in Program MARK to estimate N for a Black Bear population in Great Smoky Mountains National Park, Tennessee. We systematically reduced the number of those samples used in the analysis to evaluate the effect that changes in capture probabilities may have on parameter estimates. Model-averaged N for females and males were 161 (95% CI = 114–272) and 100 (95% CI = 74–167), respectively (pooled N = 261, 95% CI = 192–419), and the average weekly was 0.09 for females and 0.12 for males. When we reduced the number of samples of the empirical data, support for heterogeneity models decreased. For the simulation analysis, we generated capture data with individual heterogeneity covering a range of sampling conditions commonly encountered in DNA-based capture-mark-recapture studies and examined the relationships between those conditions and accuracy (i.e., probability of obtaining an estimated N that is within 20% of true N), coverage (i.e., probability that 95% confidence interval includes true N), and precision (i.e., probability of obtaining a coefficient of variation ≤20%) of estimates using logistic regression. The capture probability for the larger of 2 mixture proportions of the population (i.e., pA or pB, depending on the value of π) was most important for predicting accuracy and precision, whereas capture probabilities of both mixture proportions (pA and pB) were important to explain variation in coverage. Based on sampling conditions similar to parameter estimates from the empirical dataset (pA = 0.30, pB = 0.05, N = 250, π = 0.15, and k = 10), predicted accuracy and precision were low (60% and 53%, respectively), whereas coverage was high (94%). Increasing pB, the capture probability for the predominate but most difficult to capture proportion of the population, was most effective to improve accuracy under those conditions. However, manipulation of other parameters may be more effective under different conditions. In general, the probabilities of obtaining accurate and precise estimates were best when  ≥ 0.2. Our regression models can be used by managers to evaluate specific sampling scenarios and guide development of sampling frameworks or to assess reliability of DNA-based capture-mark-recapture studies. © 2013 The Wildlife Society.

  • assessing American Black Bear habitat in the mobile tensaw delta of southwestern alabama
    Ursus, 2005
    Co-Authors: Kent R. Hersey, Andrew S. Edwards, Joseph D Clark


    Abstract American Black Bears (Ursus Americanus) have been extirpated from all but a few areas in southwestern Alabama, and the remaining habitat is being rapidly lost to development. Remnant Bear populations exist near extensive (>125,000 ha) bottomland hardwood forests in the Mobile–Tensaw Delta (MTD), but those bottomland areas are rarely used by Bears. Reintroduction of Black Bears to the MTD may improve viability of the remaining Bear populations in southwestern Alabama. To evaluate the suitability of this area for Bears, we compared habitat conditions at the MTD with similar alluvial habitats at White River National Wildlife Refuge (White River NWR), where Bears are numerous. We measured overstory, midstory, and understory vegetation in the MTD and on the North and South management units at White River NWR. We used principal components analysis and principal variable selection to identify 9 variables associated with 5 principal components (hard mast, soft mast, cavity tree availability, large tree a…