Female Black Bears Research Articles

Estimates of Abundance and Harvest Rates of Female Black Bears Across a Large Spatial Extent

ABSTRACTAmerican black bears (Ursus americanus) are an iconic wildlife species in the southern Appalachian highlands of the eastern United States and have increased in number and range since the early 1980s. Given an increasing number of human‐bear conflicts in the region, many management agencies have liberalized harvest regulations to reduce bear populations to socially acceptable levels. Wildlife managers need reliable population data for assessing the effects of management actions for this high‐profile species. Our goal was to use DNA extracted from hair collected at barbed‐wire enclosures (i.e., hair traps) to identify individual bears and then use spatially explicit capture‐recapture methods to estimate female black bear density, abundance, and harvest rate. We established 888 hair traps across 66,678 km2 of the southern Appalachian highlands in Georgia, North Carolina, South Carolina, and Tennessee, USA, in 2017 and 2018, arranged in 174 clusters of 2–9 traps/cluster. We collected 9,113 hair samples from those sites over 6 weeks of sampling, of which 1,954 were successfully genotyped to 462 individual female bears. Our spatially explicit estimator included a percent forest covariate to explain inhomogeneous bear density across the region. Densities ranged up to 0.410 female bears/km2 and regional abundance was 5,950 (95% CI = 4,988–7,098) female bears. Based on hunter kill data from 2016 to 2018, mean annual harvest rates for females were 12.7% in Georgia, 17.6% in North Carolina, 17.6% in South Carolina, and 22.8% in Tennessee. Our estimated harvest rates for most states approached or exceeded theoretical maximum sustainable levels, and population trend data (i.e., bait‐station indices) indicated decreasing growth rates since about 2009. These data suggest that the increased harvest goals and poor hard mast production over a series of prior years reduced bear population abundance in many states. We were able to obtain reasonable population abundance and density estimates because of spatially explicit capture‐recapture methods, cluster sampling, and a large spatial extent. Continued monitoring of bear populations (e.g., annual bait‐station surveys and periodic population estimation using spatially explicit methods) by state jurisdictions would help to ensure that population trajectories are consistent with management goals. © 2021 The Wildlife Society.

Comparison of Anesthetic Responses Induced by MZT and XZT Combinations at General Anesthesia for Laparoscopic Salpingectomy in Rearing Female Asiatic Black Bears (Ursus thibetanus)

Comparison of Anesthetic Responses Induced by MZT and XZT Combinations at General Anesthesia for Laparoscopic Salpingectomy in Rearing Female Asiatic Black Bears (Ursus thibetanus)

Influence of Food Availability on Matrilineal Site Fidelity of Female Asian Black Bears

Abstract. To describe the maintenance process of matrilineal site fidelity in large, solitary mammals, we investigated both the site fidelity over time and the effect of kinship on the space use at a fine (home range) scale under different levels of food availability. We collected location data for female Asian black bears, Ursus thibetanus, using GPS collars and identified microsatellite DNA markers from bears in the Ashio-Nikko Mountains, Japan. We investigated autumn food resources by assessing hard mast productivity. We found high site fidelity over the years from the denning to summer season, and there was spatial proximity among related females (i.e., mother—daughter, grandmother—granddaughter, and sister—sister pairs) from spring to summer and through mid-autumn in moderate/good hard mast years. In autumns of poor hard mast years, although females used sites far from their primary home ranges, they returned to sites near their primary range before den entry. In habitats, where good denning habitat ...

Home-Range Dynamics of FemaleUrsus americanus(Pallas) (American Black Bear) in a Recovering Population in Western Maryland

Abstract Western Maryland's population of Ursus americanus (American Black Bear; hereafter Black Bear) was nearly extirpated by the 1950s but recovered to 326 individuals by 2005. A knowledge gap currently exists regarding home-range dynamics of this recovering population. One of the most basic questions that managers wish to understand is how much space these Black Bears are using. To provide this information, we examined the home-range dynamics of 18 adult female Black Bears in western Maryland from 2006 to 2007 using GPS collars. We predicted that home-range estimates in our study population would be similar to that of surrounding states because Black Bear populations have been recovering for the past 50 years throughout Appalachia. Fixed-kernel estimates for spring, summer, and fall home ranges were 8.9 km2, 15.4 km2, and 20.7 km2, respectively. Fall and summer home ranges were similar, and both were larger (P < 0.10) than spring home ranges. Solitary females had spring home ranges 6.9 times larger th...

Movements of Female Black Bears in Relation to Landscape Vegetation Type in Southern Quebec

Few studies have examined the influence of distribution of vegetation types at the landscape level on movement of bears in and around a protected area. We analyzed movement and spatial use patterns of 19 adult female black bears (Ursus americanus) in relation to distribution of vegetation types in and near La Mauricie National Park (LMNP), Quebec, Canada, between July 1990 and December 1992. The home range of radiotracked females included a core area of 11.6 km 2 in 1991 (n = 9) and 13.3 km 2 (n = 14) in 1992. The proportion of locations in this core area was correlated (P < 0.050) with the availability of early-successional stands and maple-beech forests that provide 2 important food sources for bears (i.e., soft mast, beechnuts). In 1991-92, bears were located more often (P < 0.050) inside the park between late April and mid-July than during the period of soft-mast ripening between mid-July and mid-September. The declining use of the park during the period of soft-mast ripening was caused by the low occurrence of early-successional stands inside the park, and increased the vulnerability of female black bears to human-related mortality. This vulnerability would probably decrease if early-successional stands were maintained inside the park, and if a surrounding buffer zone was established. In this buffer zone, agriculture and residential developments should be prohibited, and hunting should be restricted to the spring period.

Nipple Dimensions and Reproductive Status of Northeastern Minnesota Female Black Bears (Ursus americanus)

Nipple Dimensions and Reproductive Status of Northeastern Minnesota Female Black Bears (Ursus americanus)

Reproductive Biology of Female Black Bears in Relation to Body Mass in Early Winter

We examined the influence of body mass in early winter on litter size, growth and sex ratio of young, as well as the influence of gestation and lactation on overwinter loss of mass among female black bears ( Ursus americanus ) in La Mauricie National Park, Quebec, Canada. All adult females weighing ≥77 kg gave birth and no female reproduced when weighing <56 kg. Litter size (two to four young) was influenced by maternal condition in early winter, and overwinter loss of mass greater for females producing litters of three and four young. For a particular litter size, heavier females tended to produce more male young than expected from an equal sex ratio. Maternal condition, however, could not explain the strongly male-biased sex ratio (2.5 males: 1.0 female) at birth observed in this population. Significance of sex ratio at birth in relation to the regulation of the population of bears at La Mauricie National Park is discussed.

Daily Activity Patterns of Female Black Bears in a Northern Mixed-Forest Environment

Activity patterns of 15 female black bears ( Ursus americanus ) were studied using motion-sensitive radiotransmitters during late summer and autumn of 1990 and 1991 in La Mauricie National Park, Quebec. Female black bears primarily were diurnal during this period, and no difference in activity patterns was detected between solitary females and females with young. Onset of activity followed sunrise by an average of 30 min, and cessation occurred on average 141 min after sunset. Activity and resting periods averaged 245 and 57 min, respectively. The proportion of active bears was highest during the ripening time of berries ( Rubus idaeus , Vaccinium myrtilloides , and Prunus virginiand ) in late August and of beechnuts ( Fagus grandifolid ) in early October. Bears denned earlier in 1991 than in 1990, probably because of the poor beechnut crop.

Denning Chronology of Female Black Bears: Effects of Food, Weather, and Reproduction

We studied factors affecting the chronology of denning by 104 female black bears ( Ursus americanus ) from three areas in Maine from 1982 to 1988. At two areas in northern Maine, entry into dens followed an alternate-year pattern with most bears denning in mid to late October when beechnuts ( Fagus grandifolia ) were scarce, and in mid to late November the next year when nuts were abundant. This pattern may have occurred for ≥11 years and has not been reported previously for a black bear population. From 1986 to 1988, patterns of habitat use reflected another behavioral response to beechnut crops; bears used hardwood forests more during autumns when nuts were abundant. Annual variation in den entry was not strongly associated with weather patterns during autumn. Where beech trees were less common in central Maine, den entry and habitat use varied less among years. Pregnant females tended to den earlier than other females. Den emergence was similar among reproductive classes, generally occurring during April within 7 days of the final snow melt. Denning periods for individuals ranged from 134 to 197 days. We concluded that black bears generally remain active in autumn until a negative energy balance occurs, but we hypothesized that pregnant females may den after they store adequate fat reserves for reproduction.

Spatiotemporal Patterns of Macrohabitat Use by Female Black Bears during Fall

We compared habitat use and movements of 82 radio-collared female black bears (Ursus americanus) at 3 dissimilar study areas in Maine during fall from 1986 to 1988. We focused on the use of northern hardwood forests containing American beech (Fagus grandifolia). Many beech forests in the northeastern United States have been infected with beech bark disease, which may limit beechnut availability. At the Spectacle Pond and Stacyville study areas, annual variation in habitat use was pronounced and was related to abundance of beechnuts. Bears used hardwood forests more when beechnuts were abundant (1986 and 1988) than when beechnuts were scarce (1987). At the Bradford study area, where habitat was more diverse and beech trees were less common, habitat use did not vary annually, and use of hardwoods and softwoods was proportional to availability. Maximum fall movements by bears, away from summer ranges, did not vary annually within areas. Fall movements were greater for bears at Stacyville (median = 7.3 km, n = 19 bear-years) than at Spectacle Pond (median = 1.3 km, n = 52) or at Bradford (median = 0.9 km, n = 28) and reflected distribution of food resources on a landscape scale. In all areas, most long movements (7.7-78.6 km) during fall were to hardwood forests when beechnuts were abundant. Bears usually denned within or near (<1.0 km) their summer ranges despite long fall movements. We provide recommendations for managing northern hardwoods to maintain beechnut production. Int. Conf. Bear Res. and Manage. 9(l):339-348 Reproduction and recruitment of black bears have been correlated with availability of mast (Rogers 1987, Eiler et al. 1989, Elowe and Dodge 1989). American beech is a component of the northern hardwoods forest type, and beech mast is eaten by black bears during fall (Hugie 1982, Elowe and Dodge 1989). Beech bark disease has caused extensive mortality of beech trees throughout northeastern United States (Houston 1975, Miller-Weeks 1983), with mortality exceeding 50% in some forests in Maine (Miller-Weeks 1983). In North America, beech bark disease is caused by a fungus (especially Nectria coccinea var. faginata) that infects the feeding wounds in the bark made by the beech scale (Cryptococcus fagi) (Houston 1975). This disease was first reported at Maine in the 1930s (Houston 1975), but another disease outbreak may be occurring now because of the age and size structures of recovering beech forests (Houston 1975, Houston and Valentine 1988). Beech bark disease can reduce beechnut production in infected forests (CM. Costello, Adirondack Ecol. Cent., pers. commun.). Habitat use by black bears has been examined in the Northeast (Hugie 1982, Lamb 1983, Elowe 1984, Meddleton 1989), but these studies did not test relationships between availability of mast and habitat use by bears during fall. Previous studies focused on spring and summer (Meddleton 1989), combined data for all seasons (Hugie 1982, Lamb 1983), or combined data from several years in which abundance of mast differed (Hugie 1982, Elowe 1984). Seasonal movements by black bears are mainly governed by distribution, phenology, and abundance of preferred foods (Garshelis and Pelton 1981, Pelchat and Ruff 1986, Rogers 1987). Comparing fall movements of bears from different environments should provide insight into foraging behavior and importance of forest ypes. Except for Hugie (1982), previous studies in northeastern United States were conducted at only 1

Reproductive History of Female Black Bears from Dental Cementum

Reproductive History of Female Black Bears from Dental Cementum

Seasonal Movements of Female Black Bears in the Boreal Forest of Ontario in Relation to Timber Harvesting

Seasonal Movements of Female Black Bears in the Boreal Forest of Ontario in Relation to Timber Harvesting

Serial Changes in Metabolic Correlates of Hibernation in Female Black Bears

Captive female black bears were immobilized and sampled at approximately 10-day intervals from September to March during 2 years (six bears/year) in Virginia. Ten of 12 bears hibernated for an average of 92 days. Rectal temperature declined (P < 0.001) during hibernation to as low as 34.6°C. Average loss in mass for hibernators was 260 g/day and represented 23.1% of peak body mass. Urea : creatinine ratios differed (P < 0.01) after hibernation between hibernators and active bears, declining to 7.2 ± 0.3 (X̄ ± SE; 84 samples) during hibernation. Serum concentrations of total protein, urea nitrogen, creatinine, and bilirubin also differed (P < 0.01) between groups after onset of hibernation. Urea : creatinine ratio was a good indicator of the hibernating state, but the sensitivity of serum-urea concentrations to diet suggests careful use of this ratio as a field index of hibernation.

Habitat use of an Arizona Ponderosa Pine—Mixed Conifer Forest by Female Black Bears

Abstract Fourteen adult female black bears were captured and radio-collared on the Mogollon Rim in north-central Arizona. Habitat use was sampled on 182 sites from May 1982-August 1984 using ground radio telemetry to identify habitat use sites. Eighty-eight sites were classified as feeding sites, and 94 sites contained beds. Analysis of use versus availability of vegetation types, topographic site characteristics, and percent slope classes showed significant differences. Females, with and without cubs, selected mixed conifer more frequently than ponderosa pine areas. Canyon walls were selected more frequently than ridgetops, especially for bedding sites. There were significant differences in amount of vegetative cover between feeding and bedding sites. Horizontal cover averaged 45 ft for bedding sites and 65 ft for feeding sites. Seventy four percent of the beds were on the uphill side of trees. Bed trees averaged 28.6 in. dbh. Habitat management recommendations are included. West. J. Appl. For. 4(1): 6-10, January 1989.