Wildlife Research and Education Foundation, Frenchtown, MT 59834, USA.
MPG Ranch, Florence, MT 59833, USA.
Behav Processes. 2024 Jan;214:104972. doi: 10.1016/j.beproc.2023.104972. Epub 2023 Nov 26.
American black bears (Ursus americanus) may be more social than currently understood. We used long-term video and genetic data to evaluate social interactions among wild, independent-aged black bear on a conservation property in western Montana, USA. We used multinomial logistic regression to evaluate predictions about male-male interactions within the context of individual fitness, female-female interactions within the context of inclusive fitness, and male-female interactions within the context of female counterstrategies to infanticide. Overall, our findings challenged the assumption that independent-aged bears interact only during the mating season or when concentrated feeding sites are present. We documented 169 interaction events by at least 66 bear pairs, 92 (54%) of which occurred outside of the peak mating season and in the absence of concentrated feeding sites. The probability that male-male pairs engaged in play and other non-agonistic behaviours was higher than that for female-female pairs. Conversely, the probability that female-female pairs engaged in chase behaviour was higher than that for male-male and male-female pairs. We documented evidence of female mate choice, female resource defense, sexually selected infanticide (SSI), and female counterstrategies to avoid SSI. Our findings improve our understanding of ursid ethology and underscore the complexity of ursid sociality.
美洲黑熊（Ursus americanus）可能比目前人们所理解的更具社会性。我们使用长期的视频和遗传数据来评估美国蒙大拿州西部一个保护地中野生、独立年龄的黑熊之间的社会互动。我们使用多项逻辑回归来评估个体适应度背景下雄性间的相互作用、适合度背景下雌性间的相互作用以及雌性反杀对策背景下雄性-雌性间的相互作用的预测。总的来说，我们的研究结果挑战了这样一种假设，即独立年龄的熊仅在交配季节或集中的觅食地点存在时才会相互作用。我们记录了至少 66 对熊的 169 次相互作用事件，其中 92 次（54%）发生在交配高峰期之外，且没有集中的觅食地点。雄性-雄性对进行游戏和其他非攻击性行为的可能性高于雌性-雌性对。相反，雌性-雌性对进行追逐行为的可能性高于雄性-雄性和雄性-雌性对。我们记录了雌性配偶选择、雌性资源防御、性选择杀婴（SSI）和雌性反杀对策的证据。我们的研究结果提高了我们对熊科动物行为学的理解，并强调了熊科动物社会性的复杂性。
