Animal-borne video systems provide insight into the reproductive behavior of the Asian black bear

Previous studies on the mating system of the Asian black bear (Ursus thibetanus) have been limited to observations of captive populations and estimations of multiple paternities. Hence, the mating system of wild bears remains poorly understood. Animal-borne camera systems (i.e., cameras mounted on animals) provide novel tools to study the behavior of elusive animals. Here, we used an animal-borne video system to record the activities of wild bears during the mating season. Video camera collars were attached to four adult Asian black bears (Male 'A' and 'B', and female 'A' and 'B') captured in Tokyo, central Japan, in May and June 2018. The collars were retrieved in July 2018, after which the video data were downloaded and analyzed in terms of bear activity and mating behavior. All the bears were found to interact with other uniquely identifiable bears for some of the time (range 9–22 days) during the deployment period (range 36–45 days), and multiple mating in males were documented. Both males and females exhibited different behaviors on social days (i.e., days when the bear interacted with conspecifics) compared to solitary days (i.e., days with no observed interactions with conspecifics). Compared to solitary days, the bears spent a lower proportion of time on foraging activities, and higher proportion of time on resting activities on social days. Our results suggest that Asian black bears have a polygamous mating system, as both sexes consort and potentially mate with multiple partners during a given mating season. Furthermore, bears appeared to reduce their foraging activities on social days, and engaged more in social interactions.此前针对亚洲黑熊（Ursus thibetanus）交配系统的相关研究，仅局限于圈养种群的行为观察以及多重父权的估算范畴，因此野生黑熊的交配系统仍未得到充分解析。动物搭载式摄像系统（即安装于动物体表的摄像机）为研究难以直接观测的野生动物行为提供了全新技术手段。本研究依托动物搭载式视频摄像系统，对交配季野生黑熊的活动行为进行了记录。2018年5至6月，研究人员在日本中部东京地区捕获4只成年亚洲黑熊（雄性A、B，雌性A、B），并为其安装了项圈式摄像机。所有项圈均于2018年7月回收，随后研究人员下载并分析了视频数据，重点解析黑熊的活动模式与交配行为。在为期36至45天的设备部署周期内，所有黑熊均有9至22天的时段与其他可唯一识别的同类个体发生互动，且研究记录到雄性个体存在多次交配行为。相较于独处日（未观测到与同种个体互动的日期），黑熊在社交日（与同种个体发生互动的日期）表现出显著不同的行为模式：与独处日相比，其觅食活动的时间占比更低，而休息活动的时间占比更高。本研究结果表明，亚洲黑熊采用多配偶交配系统：在单个交配季中，雌雄个体均可与多个伴侣结成伴侣关系并完成交配。此外，黑熊在社交日会减少觅食活动的投入，转而更多地参与社交互动。