Brown Bear Ursus Arctos Population Research Articles

Determining the distribution factors of an endangered large carnivore: A case study of the brown bear Ursus arctos population in the Central Zagros Mountains, Southwest Iran

Determining the distribution factors of an endangered large carnivore: A case study of the brown bear Ursus arctos population in the Central Zagros Mountains, Southwest Iran

Inadvertent shooting of brown bear cubs in Finland: what can managers do to reduce it?

Family groups with cubs-of-the-year (cubs) in Finland's brown bear Ursus arctos population are protected from hunting, but sport hunters inadvertently shoot some cubs almost every year. In our data, 39 of 1463 bears from hunting bags (and 39 of all 1503 shot bears) during 1996–2018 were cubs. Mortality of cubs owing to inadvertent shooting by hunters was estimated to be relatively low (ca 8%) and was therefore above all an ethical problem. Male bias from the 1:1 sex ratio was significant (67%, χ2 = 4.333, p = 0.037) and possibly attributed to a greater resemblance with yearlings (legal game) given their larger body size. The year trend in the proportion of cubs in hunting bag was not significant (t = -1.832, p = 0.076) We examined whether the risk of cub to being killed by hunters was related to the distance from the Russian border because bear hunting has been practised for more years in eastern Finland compared with mid- and western Finland. The risk of cub being killed was not related to the distance but the risk of female cubs being killed was highest within a narrow zone at the Russian border. If the family group escapes to the Russian side, the risk of losing the hunting dog is presumably high. Given hunters' high motivation to keep their valuable bear-hunting dogs, the proportion of female cubs might be highest near the border. Systematic educational programs for hunters would likely reduce the risk of inadvertent killing of cubs. The full legal protection of all family groups is potentially the most efficient method to reduce the risk and thereby formally provide improved ethics in bear hunting. However, this practice might also prolong the mother–offspring bond.

Has the sex-specific structure of Finland's brown bear population changed during 21 years?

Gene flow between the two brown bear Ursus arctos populations of Fennoscandia is very weak although bear populations both in Finland and Scandinavia has been increasing substantially during the last 50 years. We examined spatial and temporal pattern in the proportion of adult females in Finland's bear population. First, we expected evidence for decreasing female proportions with increasing distance from the potential core areas in Russia and near Finnish–Russian border. Secondly, we expected increasing proportions of females during our study period of 21 years, i.e. two brown bear generations. We conducted a logistic mixed effects model that would predict a hunter-killed bear's sex based on year, the distance from the source population (Finnish–Russian border), bear management area and bear's age group (adult, sub-adult) as independent variables. Geographic coordinates were used to reduce the apparent spatial autocorrelation. Because female bears form kin clusters, in the final model we used exponential spatial autocorrelation, based on the assumption that the probability of a dead bear being a female increased when the nearest dead bear also was a female. The model demonstrated that the population's population structure did not change spatially during our study period. The only differentiating variables were bear management area and age group, the probability of females being low in reindeer husbandry area, and males predominating among subadults. Because the low proportion of females in Finland's reindeer husbandry area may weaken meta-population viability in Fennoscandia, bear management in northern Finland should save females more efficiently.

Determinants and patterns of habitat use by the brown bearUrsus arctosin the French Pyrenees revealed by occupancy modelling

AbstractThe Pyrenean brown bearUrsus arctospopulation in the mountains between France and Spain is one of the smallest and most threatened populations of large carnivores in Europe. We assessed trends in brown bear habitat use in the Pyrenees and investigated the underlying environmental and anthropogenic drivers. Using detection/non-detection data collected during 2008–2014 through non-invasive methods, we developed dynamic occupancy models, accounting for local colonization and extinction processes. We found two non-connected core areas of occupancy, one in the west and the other in the centre of the Pyrenees, with a significant decrease in habitat use overall during 2008–2014. We also found a negative correlation between human density and bear occupancy, in agreement with previous studies on brown bear habitat suitability. Our results confirm the Critically Endangered status of the Pyrenean population of brown bears.

The brown bear Ursus arctos population in Lar Wildlife Refuge, northern Iran

AbstractBasic information about an animal population is essential to produce management and conservation strategies. Little is known about the brown bears

Challenges of managing a European brown bear population; lessons from Sweden, 1943–2013

‘Adaptive management’, which has been defined as the repeated iteration between management action, scientific assessment and revised management action, leading to a strengthened foundation for management, is required by Swedish law to be incorporated into the management of large carnivores. We have evaluated whether the size and/or trend of the brown bear Ursus arctos population in Sweden corresponded to management‐decided national objectives during five management regimes during the past 70 years (1943—2013). We found that the objective had been met in only one period, when it had been worded very vaguely. During the last period studied (2008—2013), when management was carried out on the county level and adaptive management was required by the Swedish Government, four of six counties met their trend objectives, but only one of six met the population objectives, although one was close to meeting them. Sociological studies have documented major problems in communication among the members of the county delegations responsible for the management of large carnivores. As adaptive management apparently never has been implemented successfully in brown bear management in Sweden, we recommend that the Delegations for Game Management be mandated to integrate up‐to‐date, scientifically documented biological information into their decisions. This is not done consistently today. Researchers should be involved in the process to inform about relevant, available information, design testable scientific ‘experiments’ based on the predicted results of management decisions, and evaluate the results in relation to the predictions, perhaps as members of a ‘boundary organization’ consisting of researchers, managers and stakeholders. This would require a new management paradigm, because many in Sweden seem to be skeptical to the idea of involving researchers in management.

Land Use and Land Cover Change in Protected Areas: Using Remote Sensing to Survey Suitable Habitats of Brown BearUrsus arctos

ABSTRACT In recent years, brown bear Ursus arctos populations in Iran have experienced a clear trend of reduction and the species is now officially listed as threatened under provincial legislation. Anthropogenic habitat alteration and increasing human access to previously remote landscapes are potential source of stress for this species in Iran. Therefore, land cover changes in the Chelcheli protected area were mapped for 1991–2013 using time sequential Landsat TM and ETM at 30 meters resolution. Moreover, Maximum entropy (MaxEnt) modeling was used to investigate habitat selection of brown bear. The results showed that suitable patches overlapped with forest areas (Hyrcanian forest) and rivers. Our results also indicate that the brown bear habitat suitability is negatively influenced by human disturbance (e.g., roads, settlements). Increased human disturbance in brown bear habitat in recent decades may cause bears to avoid the disturbed areas. Therefore, the management plans should focus on reducing the ...

Estimating the population size of the endangered Cantabrian brown bear through genetic sampling

The Cantabrian brown bear Ursus arctos population can be seen as a paradigm in conservation biology due to its endangerment status and genetic uniqueness. Therefore, the need to obtain basic demographic data to inform management actions for conservation is imperative. Despite this, empirical data on the size and trends of the Cantabrian bear population are scarce. Here we present the first estimates of population size (Nc) and effective population size (Ne) of the whole Cantabrian brown bear population. We genotyped 270 non‐invasive samples collected during 2006 throughout the entire range of the population and subsequently identified 130 individuals. Different model estimators of Nc based on capture—markrecapture (CMR) procedures were compared. The average for the best three models (Mh Chao, Mh Darroch and CAPWIRE TIRM) yielded a total estimate of Nc = 223 individuals (CI95% = 183–278) and Ne 50 (CI95% = 36–75) providing an Ne / Nc ratio of 0.22. Estimates for the two subpopulations commonly recognized in the Cantabrian range were Nc = 203 (CI95% = 168–260) and Ne = 47 (CI95% = 36–70) for the western subpopulation and Nc = 19 (CI95% = 12–40) and Ne= 9 (CI95% = 8–12) for the eastern subpopulation. These data suggest that the Cantabrian brown bear population has increased recently, mainly in the western subpopulation, after a long period of decline and isolation which lead to the split of the population at the beginning of the 20th century. Population sizes in the early 1990s were thought to be only 60 individuals for the western subpopulation and 14 individuals in the eastern one. The efforts to improve conservation policies made since then have probably contributed, to some extent, to the population increase during the last couple of decades.

Brown bear habitat suitability in the Pyrenees: transferability across sites and linking scales to make the most of scarce data

Summary1. Identification of suitable habitats for small, endangered populations is important to preserve key areas for potential augmentation. However, replicated spatial data from a sufficient number of individuals are often unavailable for such populations, leading to unreliable habitat models. This is the case for the endangered Pyrenean brown bear Ursus arctos population, with only about 20 individuals surviving in two isolated groups.2. We conducted habitat suitability analyses at two spatial scales (coarse and local). Given the limited available data, we used information from the nearby Cantabrian brown bear population in Spain to develop a two‐dimensional model (human and natural variables) at a coarse scale, based on logistic regression, which we applied in the Pyrenees. At a local scale, we used bear presence in the Pyrenees to describe the population’s ecological niche and develop a habitat suitability model using presence‐only methods. We combined these models to obtain a more integrative understanding of bear requirements.3. The coarse‐scale model showed a good transferability to the Pyrenees, identifying preference for areas with high forest connectivity, masting trees, rugged terrain and shrubs and avoidance of areas with anthropogenic structures. The local‐scale model was consistent with the coarse‐scale model. Bears showed a trade‐off between food resources (scarcer at high elevations) and human presence (higher at low elevations).4. Our models illustrated that there is unoccupied good habitat for bears in the Pyrenees that could host new individuals. Combining two scales allowed us to identify areas that should be prioritized for management actions and also those that should be easier to manage for bears.5. Synthesis and applications. Our study illustrates how a nested‐scale approach, combining coarse data from a different population and fine‐scale local data, can aid in the management of small populations with limited data. This was applied to remnant brown bear populations to identify priorities for conservation management.

Estimating population size and trends of the Swedish brown bear Ursus arctos population

AbstractEstimating population size and trends are key issues in the conservation and management of large carnivores. The rebounding brown bear Ursus arctos population in Sweden is monitored by two different systems, both relying on voluntary resources. Population estimates have been calculated using Capture‐Mark‐Recapture methods, based on DNA‐based scat surveys in five of the six Swedish counties with established bear populations. A total of 1,358 genotypes were identified using DNA extracted from collected scats. An independent ongoing programme, the Large Carnivore Observation Index (LCOI), was initiated in 1998. The LCOI uses effort‐corrected observations of bears by moose Alces alces hunters during the moose hunt (> 2 million observation hours/year) and has shown a good correlation with relative population density of bears using the DNA‐based method. From this, we have calculated population trends during the period 1998‐2007. Using an exponential model, we estimated the yearly increase in the bear population to be 4.5% at the national level, varying between 0 and 10.2% in different counties. We used the regional population estimates and the trends from the LCOI, taking the variation from both systems into account using parametric bootstrapping, to calculate the regional as well as the national population size in Sweden in fall 2008. In one case (the northernmost county; Norrbotten) a DNA‐scat survey was lacking, so we used assumptions based on data from the neighbouring county to estimate population size. We estimated the Swedish brown bear population to be 3,298 individuals (2,968‐3,667; 95% confidence intervals) in 2008. Our results suggest that reliable information, necessary for the management of the brown bear population can be obtained from volunteers using standardised methods.

Comparing opportunistic and systematic sampling methods for non‐invasive genetic monitoring of a small translocated brown bear population

Summary 1. Non‐invasive genetic sampling (NGS) of hair and faeces has become an important tool for monitoring wildlife populations, but many managers question the feasibility and cost‐effectiveness of these methods for long‐term monitoring. To address this question, more studies are needed that simultaneously evaluate the effectiveness and efficiency of multiple NGS designs in the same study area. 2. In 2003–2004, we carried out an experimental study of NGS for a small brown bear Ursus arctos population established by translocation in the Italian Alps. We evaluated and compared the effectiveness and efficiency of three NGS approaches including two systematic designs, baited hair traps and transect sampling of hair and faeces, and opportunistic collection of faecal and hair samples. Effectiveness was evaluated in terms of the number of samples collected, bears identified, genotyping success and error rate, detection frequencies, individual movement and spatial distribution of the species. We also evaluated the suitability of the data collected for population size estimation using single‐ and multi‐session approaches. Efficiency was assessed by calculating total cost/genotyped sample, cost/unique bear identified and cost/bear sample. 3. During 2 years of sampling, 1164 samples and 15 unique genotypes were obtained. From these genotypes, we documented reproduction, an increase in the minimum population size of bears in the study area and important information on specific bears causing damages to property. 4. The optimal sampling strategy combined systematic hair trapping and opportunistic sampling, as the pooled data set efficiently provided large sample quantities, the highest number of identified bears, multiple individual detections, information on bear distribution and suitable data for population size estimation. 5. We provide an example of how the efficiency of NGS monitoring can be improved by integrating sampling into routine duties of existing field personnel. 6. Synthesis and applications. This study provides baseline data for monitoring brown bears in the Italian Alps and has important implications for NGS of other small populations in human‐dominated landscapes. Conservation of small populations in such habitats will benefit from multiple strategies that obtain critical demographic, spatial and genetic information in a cost‐effective manner.

Habitat assessment of a relict brown bear Ursus arctos population in northern Spain

We assess the habitat quality of a small remnant population of Eurasian brown bears Ursus arctos in northern Spain based on a habitat evaluation procedure and analysis of bear distribution and road density. Habitat evaluation was based on our knowledge of bear habitat requirements using a combination of radiolocation and sign data and analysis of four variables (forest cover, elevation, distance to nearest village, distance to nearest roadway). Herein, we use those results to calculate habitat suitability indices for 1 km 2 UTM cells over 3500 km 2 of bear range, by summing scores (from 0 to 1) for each variable. Roughly 15% of the study area was classified as high-quality bear habitat. In secondary bear range (sporadic presence) the average unpaved road density was more than twice as high compared to that in primary, year-round, range, and was highest in areas outside of the bear range. The applicability of our habitat evaluation procedure to other small remnant Eurasian bear populations is proposed.

Inbreeding depression in brown bear Ursus arctos

This note reports the occurrence of inbreeding depression in a captive brown bear Ursus arctos population. We analyzed studbook records of brown bears bred in Nordic zoos and found a significant reduction in litter size following an increase of inbreeding. In addition, albinism is associated with inbreeding in this population. The amount of depression is compared to that found in other species. Our results are in disagreement with the contention that mammalian carnivores are adapted to close inbreeding.

Conservation genetics of the European brown bear--a study using excremental PCR of nuclear and mitochondrial sequences.

In the Brenta area of northern Italy, a brown bear Ursus arctos population is rapidly going extinct. Restocking of the population is planned. In order to study the genetics of this highly vulnerable population with a minimum of stress to the animals we have developed a PCR-based method that allows the study of mitochondrial and nuclear gene sequences from droppings collected in the field. This method is generally applicable to animals in the wild. Using excremental as well as hair samples, we show that the Brenta population is monomorphic for one mitochondrial lineage and that female as well as male bears exist in the area. In addition, 70 samples from other parts of Europe were studied. As others have previously reported, the mitochondrial gene pool of European bears is divided into two major clades, one with a western and the other with an eastern distribution. Whereas populations generally belong to either one or the other mitochondrial clade, the Romanian population contains both clades. The bears in the Brenta belong to the western clade. The implications for the management of brown bears in the Brenta and elsewhere in Europe are discussed.

Size, trend, distribution and conservation of the brown bear Ursus arctos population in Sweden

The density of adult (≥3 years) female brown bears Ursus arctos was estimated in two areas of Sweden from ratios of radio-marked and unmarked females consorting with radio-marked adult males during the breeding season. The resulting densities were 1·2 ± 0·81 (95% confidence interval) adult females/1000 km 2 in a northern study area and 1·06 ± 3·44 adult females/1000 km 2 in a southern area. These estimates were extrapolated to obtain a population estimate for Sweden using relative densities throughout the range of the species in Sweden, based on hunter-kill statistics, and observed rates of reproduction and juvenile and subadult survival. The total population in spring 1991 was estimated to be about 620 bears, with almost all females confined to four geographically separated areas, termed female core areas. A supplementary estimate, based on estimated kill rates of adult females in the study areas, was about 660 bears. Estimates based on hunter kill rates of marked bears gave minimum and maximum estimates of about 300 and 900 bears, respectively. Although these are not confidence intervals of the total population estimate, we believe that the true population size is included within these limits. Densities within the female core areas varied from 50 to 100% of those in similar habitats in European Russia. The bear population in Sweden appeared to have increased at a stable rate of about 1·5% annually during the past 50 years. Mean annual rate of legal harvest during 1943–1991 was estimated to be 5·5% (±2·1% SD), suggesting a maximum sustainable rate of 7·0% for this population. The harvest increased at a rate of 9·6% annually during 1981–1991, and apparently was at the maximum sustainable level during 1987–1991.

Dynamics of a small, hunted brown bear Ursus arctos population in Southwestern Alberta, Canada

We studied population dynamics of brown bears Ursus arctos in the Kananaskis Park and Bow Crow Forest of southwestern Alberta, Canada to evaluate effects of hunting. Twenty-four bears were captured and 20 were radio-monitored from 1980 to 1984. Estimated density was 1.6 bears/100 km 2, for a population size of 38 bears. Mean annual sex and age composition was 30% adult males, 22% adult females, 22% subadult males, 11% subadult females, and 15% cubs. Mean litter size of new cubs was 1.40 and mean birth or breeding interval was 3.00 years. The reproductive rate was estimated at 0.46 cubs/adult female/year. Adjusted annual survival rates were 0.70 for adult males, 0.93 for adult females, 0.89 for subadult males, 0.89 to 0.93 for subadult females, and 0.78 for cubs. Combined, these rates yield population growth rates of r s = −0.01 to r s = + 0.01. Increased hunting mortality of older adult males coincided with an influx of younger immigrant males, which apparently contributed to low reproductive rate and population decline.