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Brown bears (Ursus arctos marsicanus) in the Apennines, central Italy, survive in a precarious conservation status but the reproductive performance of the population has never been formally assessed. Each year, from 2006 to 2014, we conducted surveys of females with cubs (FWC) to estimate the minimum number of female bears that reproduced and annual productivity in this bear population. We discriminated unique family groups based on simultaneity of sightings, presence of individually recognizable bears, and ad hoc distance-based rules developed using Global Positioning System relocations from 11 adult female bears in our study population. To estimate the true number of FWC from unique counts, we applied 2 estimators (Chao2, Capwire) known to handle heterogeneity in sighting probabilities relatively well at small sample sizes. Annually, we estimated 1–6 ( = 3.9 ± 1.5 SD) unique FWC and tallied a minimum of 3–11 ( = 7.4 ± 3.0 SD) cubs in the population. No temporal trend in FWC was observed and the mean estimate of reproductive females corresponded well with an independent estimate of total population size obtained in 2011. Although we confirmed that the population is still reproductively functional, the small number of reproducing females and their year-to-year fluctuations dramatically underlined the precarious status of Apennine bears. We concur with previous authors that counts of unique FWC are an effective means to assess reproductive output in small bear populations, although it is advisable that more in-depth demographic studies complement this technique.
We opportunistically collected and analyzed 80 scats of the Asiatic black bear (Ursus thibetanus) from den entrances and other areas at 2 sites within Hormozgan Province, Iran, from March 2010 to February 2011. We identified 27 food items dominated by cultivated date palm (Phoenix dactylifera) fruit, oriental hornet (Vespa orientalis), and Christ's thorn jujube (Ziziphus spina-christi) fruit with frequency of occurrence 55.0%, 30.0%, and 20.0%; and percentage volume 75.0%, 55.8%, and 86.7%, respectively. Our study highlights the potential importance of human-related foods to Asiatic black bear diets. Our findings may help conservation managers to identify areas of notable potential conflict for Asiatic black bears and implement conflict-reducing measures such as installing better protective fences for reducing horticulture loss.
Limited information is currently available on the parasite fauna of brown bears (Ursus arctos) in Transylvania, Romania. During 2011–2015 we identified endoparasites from 211 scat samples collected from free-ranging bears and 37 samples from organ tissue of adult individuals harvested by hunters in Eastern Transylvania. We found endoparasites in 40.7% of samples overall; 37.9% of scats and 56.8% of harvested bears. We identified 6 nematodes including undetermined species of the family Ancylostomatidae, Baylisascaris transfuga, Crenosoma sp., undetermined species of the order Spirurida, Trichinella sp., and Trichuris sp. We also found one undetermined protozoan species of the subclass Coccidia, the cestode Taenia sp., and the trematode Dicrocoelium dendriticum. We did not detect seasonal variation in B. transfuga incidence, nor in overall parasite prevalences. In Transylvania, brown bears’ space use overlaps with that of domestic animals, creating a potential risk for the transmission of parasite infections. Supplemental feeding of bears and other wildlife species as part of current management practices may increase the potential for parasitic infections by artificially concentrating wildlife.
Diversionary feeding uses food to lure animals away from areas where they are unwanted or could cause conflicts with people. With bears (Ursidae) increasingly attracted to human food sources worldwide, diversionary feeding represents a seemingly logical and publicly acceptable means of alleviating conflicts. Feeding wildlife is widely practiced in Europe to enhance hunting and reduce conflicts, but feeding of bears is discouraged across North America. The efficacy and potential side-effects of bear feeding remain an open question because of a lack of rigorous studies. Here we examine 5 case studies from which we attempt to draw inferences about feeding as a conflict-mitigation strategy. Studies included U.S. national parks, where after bear feeding was banned conflicts were reduced; Aspen, Colorado, where lucrative dumpsters in town did not divert bears from using human-related foods at other sources; rural Minnesota, where results of intentional feeding of a small sample of bears were confounded with other variables; the Tahoe Basin of California–Nevada, where an emergency feeding effort during a drought-caused food failure seemed to reduce conflicts within approximately 1 km of the feeding site; and Slovenia, where a high density of feeders at established locations seemed to divert bears from using settlements during autumn hyperphagia. Although none of these studies were true experiments with treatments and controls, the range of circumstances yielded insights into when feeding could be effective: when food demands are not readily met by natural foods; when the provisioned food is easily found outside the potential conflict area; when the food is attractive; and when bears do not associate the feeding with people. However, long-term feeding may increase bear population size, which may increase conflicts overall, or trigger a demand for population control. Diversionary feeding, if used, should be conducted as an adaptive management strategy by professionals so as to learn more about factors influencing its effectiveness.
As American black bears (Ursus americanus) reoccupy portions of the eastern United States, it is important to implement sustainable management practices based in a strong understanding of the dynamics of these recovering populations as they expand into areas with increasing anthropogenic pressures. We used the Downing population reconstruction technique on harvest records to establish baseline abundance and population growth-rate trends over 15 years for a population of black bear in northwestern South Carolina, USA. The total population in 2013 was estimated to be a minimum of 412 black bears, increasing from approximately 97 bears in 1998. We established age structure and sex structure in harvest, which were consistent with sustainably harvested bear populations. We recommend using these data as a baseline to determine the maximum sustainable harvest rate for this population. We also recommend future investigation into the development of research priorities and harvest management decisions for the population to maintain desired levels of black bear recovery.
Supplemental and diversionary feeding can reduce conflicts between wildlife and people. However, feeding also can increase species abundance, survival, and reproductive success, which might increase human–wildlife conflicts. In southwestern Alberta, Canada, the provincial government fed road-killed ungulates to grizzly bears (Ursus arctos) each spring during 1998–2013 attempting to reduce spring depredation of livestock by grizzly bears. We used non-invasive genetic sampling, remote trail cameras, and complaint records to evaluate the efficacy of Alberta's intercept-feeding program. We monitored 12 intercept-feeding locations in 2012 and 2013. Using DNA, we identified 22 grizzly bears (19 M, 3 F) at the intercept-feeding sites. Remote trail cameras detected grizzly bears at all intercept-feeding sites, but detected females with dependent offspring at only 4 of the 12 sites. We reviewed complaint data for incidents before, during, and after the intercept-feeding program. We defined an incident as a situation where the grizzly bear caused property damage, obtained anthropogenic food, or killed or attempted to kill livestock or pets. Spring (1 Mar–15 Jun) grizzly bear–livestock incidents did not decrease during the intercept-feeding program (pre: 1982–1995, x̄ = 0.8 spring livestock incidents/yr, SE = 0.3, during: 1999–2013, x̄ = 3.3 spring livestock incidents/yr, SE = 1.3, t = 1.76, 27 df, P = 0.09). We also collected DNA samples from bears involved in incidents, and only 2 bears detected at intercept-feeding sites were detected also at a spring incident site. The intercept-feeding program was suspended in 2014 and 2015, and we did not detect an increase in spring livestock depredation. We estimated annual operating costs to be $43,850 Canadian dollars (CAD); initial capital equipment investment was $19,000 CAD. In total, approximately $720,600 CAD has been spent on the intercept-feeding program between 1998 and 2013. Intercept feeding did not decrease spring livestock depredation; therefore, other mitigation efforts, including electric fencing and deadstock removal, might be a more cost-effective long-term solution.
Muskoxen (Ovibos moschatus) are thought to be highly effective at defending themselves from predators. However, a decline in muskox abundance in northeastern Alaska, USA, that coincided with several instances of grizzly bear (Ursus arctos) predation observed during 2000–2006 raised concerns about the effects of predation on this population. In response, from 2007 to 2011 we estimated rates of reproduction and survival and determined rates and causes of muskox mortality on the arctic coastal plain of northeastern Alaska. Annual counts of muskox abundance (x̄ = 191) and estimates of population growth (x̄ = 0.94) indicated a stable or slowly declining population. Annual natality ranged from 0.45 to 0.86 (x̄ = 0.68) births/adult female, whereas annual survival ranged from 0.40 to 0.63 (x̄ = 0.49) for calves and from 0.73 to 0.91 (x̄ = 0.83) for adult females. Predation by grizzly bears was the most common cause of death among cases where a cause could be identified, accounting for 58% and 62% of deaths of calves and adults, respectively. Most bear predation occurred during late winter and spring when little other food was available to bears. The importance of predation compared with other mortality factors, and the change from a growing to a declining muskox population, suggest a change in either predator abundance or behavior. There is no evidence that bear abundance changed dramatically during this period, but abundance of moose (Alces alces) and caribou (Rangifer tarandus) declined substantially in the area where the muskox decline was most pronounced. This suggests bears may have increased predation on muskoxen in response to reduced availability of other ungulates. Maintaining diversity of native ungulates may help bears cope with the natural fluctuations in prey abundance often seen in arctic ecosystems.
The Highlands–Glades subpopulation (HGS) of Florida, USA, black bears (Ursus americanus floridanus) is small, genetically depauperate, and resides primarily within the endangered Lake Wales Ridge ecosystem, which has lost >85% of native habitat to land development. Habitat loss can reduce availability of critical natural foods and cause bears to increase reliance on anthropogenic foods (i.e., human-sourced); lands supporting the HGS are expected to lose >50% of remaining Florida black bear habitat in coming decades. We used scat analysis to describe seasonal food habits, investigate potential dietary responses to food shortages, and inform habitat conservation and human–bear conflict management. Florida black bears in the HGS mostly relied on native soft and hard mast and invertebrates, which are all available in endangered scrub habitat communities. Corn dispensed at hunter-operated feeding stations was a dominant food item in scats; and other alternative foods, such as citrus fruit and white-tailed deer (Odocoileus virginianus), were found in summer-collected scats when soft mast should have been prevailing. Results indicate bears may respond to soft mast shortages caused by mast failures or habitat loss by consuming anthropogenic foods (e.g., corn, deer chow, citrus fruit, and garbage), which could increase human–bear conflicts. Florida carpenter ants (Camponotus floridanus) appeared to provide a reliable compensatory food during such shortages, but they are arboreal and largely dependent on imperiled bear habitat for proliferation. We strongly suggest remnant scrub and other communities rich in soft and hard mast-producing flora be targeted for acquisition and protection to ensure persistence of Florida black bears in this diverse ecosystem. We also suggest non-lethal actions to mitigate bear habituation to anthropogenic foods be implemented to minimize human–bear conflicts and prevent unnecessary losses to the already small HGS. Our study should be repeated to investigate whether dietary shifts occur in response to impending habitat loss and to further inform population conservation, habitat protection, and conflict management.
Although knowledge of reproductive parameters is critical to project the probability of persistence of small and endangered populations, no such data are available for the relict Apennine brown bear (Ursus arctos marsicanus) population (central Italy). From 2005 through 2014, we compiled re-sight data on marked adult female bears (3 ≤ n ≤ 10/yr, for 78 total bear-years) and unmarked, distinct family groups (n = 17) to estimate basic reproductive traits in Apennine bears. We had a high rate of radiocollar failure, so we included in our sample marked, adult female bears with non-functioning radiocollars and used multi-event models in a capture–recapture, robust-design framework to correct for their incomplete detection and potential classification error. We obtained annual detection probabilities of 0.77 and 0.82 for reproductive and non-reproductive female bears, respectively, and the classification error of their reproductive state was negligible (P = 0.003). Mean litter size was 1.9 (±0.7 SD) cubs, weaning occurred at approximately 1.4 years, and the interbirth interval was 3.7 years. Based on our multi-event model, female bears had highest probability to reproduce 3–4 years after their last reproduction, and their average reproductive rate was 0.243 (95% CI = 0.072–0.594). Average survival of adult female bears was 0.93 (95% CI = 0.83–0.97) whereas apparent cub survival was 0.49, based on the proportion of cubs seen before weaning the year following birth. Our findings place reproductive parameters of the Apennine bear population at the lower bound along the spectrum reported for other non-hunted brown bear populations. Coupled with high levels of human-caused mortality, a relatively low reproductive performance may explain why Apennine bears have not expanded their range beyond their historical minimum. More in-depth demographic investigations are urgently needed to corroborate our results and to assess the relative role of density-dependence versus inbreeding depression in affecting the dynamics of this imperiled bear population.
The Andean bear (Tremarctos ornatus) is the only extant species of bear in South America and is considered threatened across its range and endangered in Ecuador. Habitat loss and fragmentation is considered a critical threat to the species, and there is a lack of knowledge regarding its distribution and abundance. The species is thought to occur at low densities, making field studies designed to estimate abundance or density challenging. We conducted a pilot camera-trap study to estimate Andean bear density in a recently identified population of Andean bears northwest of Quito, Ecuador, during 2012. We compared 12 candidate spatial capture–recapture models including covariates on encounter probability and density and estimated a density of 7.45 bears/100 km2 within the region. In addition, we estimated that approximately 40 bears used a recently named Andean bear corridor established by the Secretary of Environment, and we produced a density map for this area. Use of a rub-post with vanilla scent attractant allowed us to capture numerous photographs for each event, improving our ability to identify individual bears by unique facial markings. This study provides the first empirically derived density estimate for Andean bears in Ecuador and should provide direction for future landscape-scale studies interested in conservation initiatives requiring spatially explicit estimates of density.