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Robust estimates of demographic parameters are critical for effective wildlife conservation and management, but are difficult to obtain for elusive species. We estimated the breeding and adult population sizes, as well as the minimum population size, in a high-density brown bear population on the Shiretoko Peninsula, in Hokkaido, Japan, using DNA-based pedigree reconstruction. A total of 1,288 individuals, collected in and around the Shiretoko Peninsula between 1998 and 2020, were genotyped at 21 microsatellite loci. Among them, 499 individuals were identified by intensive genetic sampling conducted in two consecutive years (2019 and 2020) mainly by noninvasive methods (e.g., hair and fecal DNA). Among them, both parents were assigned for 330 bears, and either maternity or paternity was assigned to 47 and 76 individuals, respectively. The subsequent pedigree reconstruction indicated a range of breeding and adult (≥4 years old) population sizes: 128–173 for female breeders and 66–91 male breeders, and 155–200 for female adults and 84–109 male adults. The minimum population size was estimated to be 449 (252 females and 197 males) in 2019. Long-term continuous genetic sampling prior to a short-term intensive survey would enable parentage to be identified in a population with a high probability, thus enabling reliable estimates of breeding population size for elusive species.

Investigating factors underlying human-wildlife conflicts in agricultural landscapes is important for both preventing crop damage and wildlife conservation. Although environments surrounding crop fields are considered causal factors, incorporating individual aspects of animals, such as demographic and physical characteristics, into the investigation may aid the prediction of how nuisance control affects wildlife population structures. Here, we assessed the relationship of corn consumption by Hokkaido brown bears (Ursus arctos) with both demographic (sex and age) and physical (body size) characteristics and environmental factors (human presence and crop accessibility). We estimated the proportion of corn in the lifespan diet for both female (n = 61) and male (n = 62) bears using carbon and nitrogen stable isotope analyses. Then, we analyzed the factors correlated with corn consumption using a generalized linear model. Female and male bears consumed corn from 1.3 to 30.9% and 1.3 to 42.0% of their lifespan diet, respectively. Corn consumption by female bears was not correlated with any explanatory variables, whereas that of male bears was positively correlated with their body size and crop accessibility but negatively correlated with human presence. Large male bears were more likely to have consumed more corn than small male bears, but the selective harvest of large bears may cause dwarfism of their overall population, impacting the local population dynamics. To reduce agricultural damage and population structure alteration of brown bears, the opportunity for them to learn to eat crops must be eliminated through border management between forests and agricultural fields and the relocation of agricultural fields when possible.

Human habituation of large carnivores is becoming a serious problem that generates human–wildlife conflict, which often results in the removal of animals as nuisances. Although never tested, human habituation potentially reduces the fitness of adult females by reducing their offspring’s survival as well as their own, due to an increased likelihood of human-caused mortality. Here, we tested this hypothesis in brown bears inhabiting Shiretoko National Park, Japan. We estimated the frequency of human-caused mortality of independent young (aged 1–4 years) born to mothers living in areas with different maternal levels of human habituation and different proximities to areas of human activity. The overall mortality rate was higher in males than in females, and in females living near a town than those in a remote area of park. Surprisingly, more than 70% of males born to highly habituated mothers living around a remote wildlife protection area were killed by humans; this proportion is greater than that for males born to less-habituated mothers living in almost the same area. The current study clarified that interactions among maternal human habituation, birthplace (proximity to town), age, and sex determine the likelihood of human-caused mortality of brown bears at an early stage of life.

Male reproductive behavior has not been thoroughly investigated in large, non-social mammals. We studied male reproductive input using field observations and microsatellite DNA data for the brown bear (Ursus arctos yesoensis Lydekker, 1897) population in a special wildlife protection area on the Shiretoko Peninsula in Hokkaido, Japan. We identified the father of 82 offspring born between 2006 and 2018 from 54 litters produced by 20 females and revealed that they were sired by a total of 19 males. Overall, paternity was distributed relatively evenly among different males, although litter production tended to be skewed to a few bears in some years. Male breeding tenure varied among individuals, but most tenures were within the range of 1 to 6 years. Human-caused mortality, mostly occurring near human residential areas, induced male turnover, indicating that the special wildlife protection area located in the inner part of the Shiretoko Peninsula is not free from human impact. The frequency of successful reproduction was highest in 10- to 14-year-old bears, which is consistent with the period when males reach physical maturity. These results contribute to an understanding of breeding systems in large solitary mammals and to appropriate conservation and management strategies for brown bear populations.

Natal dispersal likely plays an important role in avoiding inbreeding among large carnivores. We tested the hypothesis that male-biased dispersal reduces close inbreeding by limiting the spatial overlap of opposite-sex pairs of close relatives in brown bears (Ursus arctos) in the Shiretoko Peninsula, Hokkaido, Japan. We genotyped 837 individuals collected in 1998–2017 at 21 microsatellite loci and performed parentage analysis. To calculate natal dispersal distance, we considered the site where the mother was identified as the birthplace of her offspring, and the site where the offspring were identified as their dispersed place. As predicted, we found that dispersal distances were significantly greater for males (12.4 km ± 1.0) than for females (7.7 km ± 0.9), and those for males increased from 3 years old, indicating that males begin to disperse around the time sexual maturation begins. Relatedness decreased with distance among pairs of females, and the mean relatedness was significantly higher between pairs of females than between pairs of males or between female–male pairs within 3 km. Closely related female–male pairs rarely (5–6%) resided in close proximity (< 3 km), compared with pairs of closely related females. Our study revealed that the potential for close inbreeding was low in Hokkaido brown bears because males are effective dispersers.

Understanding the breeding ecology of a species is essential for the appropriate conservation and management of wildlife. In brown bears, females occasionally copulate with multiple males in one breeding season, which may lead to multiple paternity in a single litter. In contrast, inbreeding, a potential factor in the reduction of genetic diversity, may occur, particularly in threatened populations. However, few studies have reported the frequency of these phenomena in brown bear populations. Here, we investigated the incidence of multiple paternity and inbreeding in a high-density brown bear population on the Shiretoko Peninsula in Hokkaido, Japan. A total of 837 individuals collected from 1998 to 2017 were genotyped at 21 microsatellite loci, and parentage analysis was performed. Out of 70-82 litters with ≥2 offspring, 14.6-17.1% of litters were sired by multiple males. This was comparable to the rate reported in a Scandinavian population, although population density and litter size, factors that potentially affect the incidence of multiple paternity, differed between the 2 populations. Out of 222 mother-father mating pairs, 6 litters (2.7%) resulted from matings between fathers and daughters. Additionally, 1 (0.5%) and 4 (1.8%) cases of mating between maternal half-siblings and between paternal half-siblings, respectively, were observed; however, no cases of mating between mothers and sons or between full siblings were observed. Our results suggest that male-biased natal dispersal effectively limits mating between closely related individuals (aside from fathers and daughters) in brown bears.

The reproductive tracts of 130 adult female brown bears (Ursus arctos) in Hokkaido, Japan, euthanized during 2010–2013 for conflict management, were examined for the presence and number of corpora lutea (CL) in the ovary and placental scars (PS) in the uterine horns. We scored PS on a 0–5 scale based on morphological features including their rim and color. They were characterized as representing either current-year parturition, as determined by accompanying cubs, or previous-year parturition, as determined by accompanying yearlings. In total, 128 females were divided into 3 reproductive categories: 44 females with current-year parturition, 39 with previous-year parturition, and 45 solitary females that had not given birth for >2 years. The estimated ovulation rate was 2.21 ± 0.55 (mean ± SD), the implantation rate was 1.91 ± 0.74, and the litter size was 1.54 ± 0.51. Implantation rates were lower than ovulation rates and changed annually during 2010–2013. Systematic observation of PS and CL allow...

Understanding natal dispersal patterns is fundamental in the ecology and conservation biology of large wild carnivores. In this study, we used two approaches to determine genetic variation and dispersal patterns of brown bears in the Shiretoko Peninsula, eastern Hokkaido, Japan. The first approach was a large-scale genetic analysis. We analyzed haplotypes from the mitochondrial DNA (mtDNA) control region of 760 individual samples collected throughout the peninsula during 1998–2016. We detected seven haplotypes, including two that were confirmed for the first time. In females, the distribution of haplotypes was geographically structured, whereas haplotypes in males were distributed widely throughout the peninsula. Only some males in the lower peninsula had haplotypes that were not detected within the peninsula. The second approach was a local-scale genetic analysis, including intensive focal sampling in the Rusha area, a special wildlife protection area on the peninsula. Proportions of mtDNA haplotypes in adult bears were investigated and compared between the sexes. Although more than half of the females had the same haplotype, males had more diverse haplotypes, suggesting that they came to the Rusha area from other regions. Thus, our study revealed that mtDNA haplotype distribution has been maintained by female philopatry, and that bears exhibit male-biased dispersal. Furthermore, the lower peninsula appears to act as a contact zone between the peninsula and mainland Hokkaido, which is important for maintaining genetic diversity.

In order to establish methodology for population estimation of Asiatic black bears using the hair-trapping method, hair-trapping devices were located within a study area, and basic data were collected to determine the optimal survey period for hair sampling. Bear hairs collected were classified as three types (guard hair; G, underfur; U, and intermediate hair; I) depending on hair-bulb thickness. After DNA extraction, six microsatellite loci and amelogenin locus were amplified in order to identify individual bears and sex, respectively. The number of hairs collected by hair-trapping devices decreased dramatically in late August, while those that had lost part of the hair bulb increased after September. The success rate of genetic analysis was over 90% prior to the month of July and rapidly decreased in August. Based on the results of the generalized linear model, it was determined that sampling session had the most significant impact on the success rate of genetic analysis of all the explanatory...

Estimating the genetic structure of a population is important for the conservation and management of wildlife. In the present study, our aim was to estimate the genetic structure of the brown bear (Ursus arctos) population in eastern Hokkaido by performing a Bayesian clustering analysis. To accomplish this goal, we used 15 microsatellites to generate genotypic data from tissue samples collected from 646 bears between 1996 and 2008. Using this genotypic data and the geographic locations where the bears were captured, GENELAND analysis detected six subpopulations. Based on the genotypic data, the STRUCTURE analysis revealed three subpopulations. As inferred from the GENELAND analysis, the core zones of the subpopulations (G-a through G-f) were located in the Shiranuka Hills (G-a), the northern area of the Shiranuka Hills (G-b), the eastern slope of the Daisetsuzan Mountains (G-c), the northern slope of the Akan Mountain Range (G-d), the Shiretoko Peninsula (G-e), and Akkeshi District (G-f). The STRUCTURE analysis indicated that G-b and G-d were influenced by gene flow from other subpopulations. National routes, towns, and farm fields were considered to have formed the distribution boundaries among the subpopulations. A high level of genetic differentiation was not observed among the six subpopulations, with the exception of G-f (Fst = 1.35–0.176, Ds = 0.246–0.349), which showed a geographically discontinuous distribution. We suggest that the loss of forest areas through future regional development and road building should be avoided to facilitate gene flow in brown bears in Hokkaido.

An electroejaculation technique was applied to the Hokkaido brown bear (Ursus arctos yesoensis) for semen collection and characterization of their seminal traits. Ten captive sexually mature bears were anesthetized and subjected to 21 electroejaculation trials during their mating season in 1995 and 1996. Spermic electroejaculates were recovered from 6 of the 10 bears (14 of 21 trials). The semen was characterized by serous fluid of semitransparent white color and a neutral pH. The mean values of ejaculate volume, sperm concentration, percentage of sperm motility, percentage of live spermatozoa, and percentage of pleiomorphic forms were 2.7 ml, 471.6 x 10(6) cells/ml, 80.2%, 89.7% and 21.8%, respectively. Although there was considerable variation among the seminal traits of the individual bears, the electroejaculation technique was effective in obtaining ejaculates from captive bears.

a b s t r a c t In Hokkaido, Japan, recent trends concerning the intrusions of the brown bear (Ursus arctos) into crop fields and a subsequent increase in agricultural damage have highlighted the need for new and more effective population management strategies. To devise such strategies, we focused on a well-defined, previously studied brown bear population living in the Oshima Peninsula region of Hokkaido, and con- structed a population dynamics model for adult females. The model construction was based on the ecological and physiological characteristics of the Oshima Peninsula population, with particular empha- sis on bear behavior (levels of aggressiveness and intrusiveness) and human-bear interactions (bear kills, food conditioning, and aversive conditioning). To predict the future population dynamics, we ran stochastic simulations over a period of 100 years. We used the simulation outputs to estimate the risk of management failure under four plausible scenarios, including the scenario that represents the present management practices. The results of the analysis indicated that the present management practices could not satisfactorily resolve the problem of increasing agricultural damage. However, an adaptive management strategy successfully reduced the risk of management failure to a negligible level. © 2012 Elsevier B.V. All rights reserved.

To develop an easy method of typing of mitochondrial DNA (mtDNA) in Hokkaido brown bears (Ursus arctos yesoensis), the PCR-RFLP technique was improved using four restriction enzymes: Mbo 1, Cfr 13 I, TspE 1, and Fok 1. This approach identified seven groups of mtDNA haplotypes, HB1/2/5-7, HB 3, HB4, HB8/9, HB10/11, HB12 and HB13 from 102 brown bears of northern, central and eastern Hokkaido.

Forty wild sika deer (Cervus nippon) were immobilized with medetomidine and ketamine and reversed by atipamezole in summer and fall captures from September 1994 to October 1995. For large yearling and older deer, mean +/- SD doses of 57.0+/-15.6 microg/kg medetomidine and 1.64+/-0.49 mg/kg (male) or 4.02+/-1.16 mg/kg (female) of ketamine were administered by intramuscular injection. For calves and small yearlings, 69.3+/-7.0 microg/kg medetomidine and 2.69+/-0.44 mg/kg ketamine were administered. While immobilized, deer were easy to handle, and muscles were well relaxed. After intramuscular administration of atipamezole (about 5 times the dose of medetomidine), deer recovered rapidly and smoothly.

Haptoglobin (Hp), a hemoglobin-binding protein, is known as an acute phase protein increasing in blood during inflammation in most mammals. On the basis of our previous studies on purification and characterization of bear Hp (Comp. Biochem. Physiol. 110B, 785–789, 1995), in this study, we developed an immunoassay method to measure serum Hp level in bear, and measured the concentration of Hp in blood samples collected from 84 reared and 25 wild brown bears in Hokkaido, Japan. The mean serum Hp concentration was 0.94 ± 0.25 mg/ml in wild bears, which is nearly equal to those reported in other species. In reared bears, the Hp concentration was apparently higher (3.82 ± 0.29 mg/ml), although total protein and albumin concentrations were nearly equal in the two groups. A significant seasonal variation of serum Hp, low in spring and high in autumn and winter, was found in reared bears. Possible factors participating in the seasonal variation were discussed with special references to hibernation.

DNA fingerprinting employing a minisatellite Myo probe was used for individual identification and paternity determination in Hokkaido brown bears (Ursus arctos yesoensis). We used two restriction enzymes, HinfI and HaeIII to make DNA fingerprints. Band patterns obtained from randomly selected bears were compared with each other, and the probability x that fragment in an individual was also present in the other was 0.69 for HinfI and 0.83 for HaeIII. The value for HinfI (0.69) was similar to that obtained from other species, such as dog and domestic animals, and the mean probability of all fragments was calculated to be 2.5 x 10(-2). The results suggest that DNA fingerprinting applying the combination of HinfI and Myo is available for individual identification. On the other hand, the ability to determine paternity seemed to be insufficient owing to the lack of paternal fragments, although the band patterns reflected the correct relationships between child and father.