Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

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.

DOI： 10.1007/s10344-018-1222-x

Web of Science

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：HOKKAIDO UNIV  

Chest girth and body mass of 3,576 brown bears (Ursus arctos yesoensis) harvested for conflict management in Hokkaido, Japan during 1991-2012 were used to establish methods to assess body condition and to compare the body condition of bears by sex, month, year, and reproductive status. The body mass was estimated based on the chest girth in cases with no measurements of the bear body mass. Using the measured and estimated body mass, a growth curve by age was demonstrated to ascertain the mean asymptotical body mass (245 kg for males, 114 kg for females) and ages at 95% asymptotic body mass (14.2 years for males, 7.1 years for females). The body condition value of bears was evaluated as body mass difference (kg) between the individual body mass and the standard body mass as estimated from the growth curve. Body condition value changed seasonally with a low in summer and the highest in the autumnal hyperphagic period. Female body condition value was higher than the males during September. Fluctuation in annual body condition value was found for females; however, there was no difference between solitary adult females and females with offspring (cubs, yearlings, or offspring of unknown age). No significant fluctuation was found for males. Our body condition evaluation method using chest girth and body mass of brown bears is useful to elucidate different trends across sex, year, and season.

DOI： 10.14943/jjvr.66.2.71

Web of Science

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

servation and management of wildlife. In this study, we investigated the demographic parameters, including age of primiparity, litter size, inter-birth interval, reproductive rate, and cub survival rate, of Hokkaido brown bears (Ursus arctos yesoensis) in the Rusha area on the Shiretoko Peninsula, Hokkaido, Japan, based on a long-term, individual-based monitoring survey. A total of 15 philopatric females were observed nearly every year from 2006 to 2016, and these observations were used to estimate reproductive parameters. The mean age of primiparity was 5.3 +/- 0.2 (SE) years (n = 7, 95% CI = 5.0-5.6). We observed 81 cubs in 46 litters from 15 bears. Litter size ranged from one to three cubs, and averaged 1.76 +/- 0.08 (SE) cubs/litter (95% CI = 1.61-1.91). Inter-birth intervals ranged from 1 to 4 years, and the mean value was estimated as 2.43 (95% CI = 2.16-2.76) and 2.53 (95% CI = 2.26-2.85) years in all litters and in litters that survived at least their first year, respectively. The reproductive rate was estimated from 0.70 to 0.76 young born/year/reproductive adult female, depending on the method of calculation. The cub survival rate between 0.5 and 1.5 years ranged from 60 to 73%. Most cub disappearances occurred in July and August, suggesting that cub mortality is mainly due to poor nutrition in the summer. All reproductive parameters observed in the Rusha area on the Shiretoko Peninsula fell within the range reported in Europe and North America, and were among the lowest or shortest age of primiparity, litter size, and inter-birth intervals, and ranked at a high level for reproductive rate.

DOI： 10.1371/journal.pone.0176251

Web of Science

PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：INT ASSOC BEAR RESEARCH & MANAGEMENT-IBA  

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 allowed us to evaluate the reproductive history and parameters in Hokkaido brown bears and ascertain their annual variation.

DOI： 10.2192/URSU-D-16-00005.1

Web of Science

Language：Japanese  

CiNii Research

J-GLOBAL

J-GLOBAL

Event date： 2025.11

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2025.10

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2025.10

Language：Japanese  

Event date： 2025.9

Language：Japanese  

Event date： 2024.11

Language：Japanese