Abstract: In the northeastern region of China, winter is characterized by a snow-covered period that can last up to half a year, with frigid temperatures and scarce food resources. To cope with these harsh environments, Asiatic black bears (Ursus thibetanus) hibernate during most of the winter, a period that also coincides with their breeding and early cub-rearing phase. Therefore, hibernation is crucial for the stability of populations in this region, and suitable dens are essential for successful hibernation. This study, conducted between 2015 and 2019 in the Wangqing National Nature Reserve in Jilin Province, identified 24 dens sites through field surveys. Using descriptive statistics, principal component analysis (PCA), and random forest modeling, we examined den structure, microhabitat, and denning habitat to explore the factors influencing den selection and the environmental factors affecting den site choice, thereby revealing the relationship between the microhabitat, denning environment, and den selection. We found that the trees selected for denning were primarily Populus cathayana, indicating a relatively narrow range of tree species compared to other studies. The denning trees had a diameter at breast height (DBH) of approximately (122. 89 ± 13. 60) cm, with den entrances measuring about (39. 26 ± 6. 62) cm in diameter. The orientation of the den entrances fell within the range of solar altitude and was sheltered from the wind, suggesting that temperature plays a significant role in den entrance selection. Entrance orientation accounted for most of the first principal component, and the DBH and entrance size constituted the second principal component. Together, these two components accounted for 0. 85 of the total variance, indicating that entrance orientation, DBH, and entrance size are the primary factors considered in den selection. The main factors influencing den site habitat selection included the distance to rivers, distance to major roads, gross primary productivity (GPP) in October, and distance to human settlements. The ecological significance of these factors suggests that the primary considerations in den site selection are safety, insulation, and access to food resources. This study provides scientific support for the conservation and restoration of denning habitats for Asiatic black bears in northeastern China.

Key words: Ursus thibetanus, Hibernation, Den, Microhabitat, Denning site habitat

摘要： 在东北地区，冬季积雪期长达半年之久，气候寒冷，食物资源匮乏，为应对严酷的环境条件，亚洲黑熊(Ursus thibetanus) 以冬眠的形式越冬，同时冬眠期也是产仔和早期育幼期，故冬眠对于东北地区的亚洲黑熊种群稳定性至关重要，而适宜的熊仓则是冬眠的必要条件。本研究于 2015—2019 年在吉林汪清国家级自然保护区，通过实地调查获得 24 个亚洲黑熊熊仓样本，采用描述统计、主成分分析和随机森林等多种统计方法，从熊仓结构、熊仓微生境和置仓生境 3 个方面探讨亚洲黑熊越冬熊仓的选择，以及影响仓址选择的环境因子，从而揭示熊仓微生境和置仓环境与熊仓选择之间的关系。研究结果显示：(1) 置仓树均为青杨 (Populus cathayana)，相较于其他研究，树种相对单一；置仓树胸径 (122.89 ± 13.60) cm，仓口大小为 (39.26 ± 6.62) cm，仓口朝向向阳且背风，表明亚洲黑熊所利用熊仓的仓口选择与温度相关。(2) 微生境研究表明，仓口方向为第一主成分且贡献率最大，说明仓口方向对熊仓的选择至关重要，胸径和仓口大小为第二主成分。第一、二主成分的贡献率达到 0.85，基本可以解释所有变量，说明仓口方向、胸径以及仓口大小是仓体选择所考虑的主要因素。(3) 影响置仓生境的主要因子为距河流距离、距主要道路距离、10 月总初级生产力和距居民点距离。从各因子相关的生态学意义来看，影响置仓选择的主要是安全性、保温性和食物资源。本研究结果可为东北地区亚洲黑熊越冬熊仓生境的保护与恢复提供科学依据。

关键词: 亚洲黑熊, 冬眠, 熊仓, 微生境, 置仓生境