The University of Texas MD Anderson Cancer Center, Michale E. Keeling Center for Comparative Medicine and Research, Bastrop, Texas.
Department of Experimental Medicine, University of Copenhagen, Copenhagen, Denmark.
Am J Primatol. 2019 Jan;81(1):e22947. doi: 10.1002/ajp.22947. Epub 2019 Jan 8.
The National Institutes of Health and the Association of Zoos and Aquariums recommend that captive chimpanzees be housed in multi-male, multi-female, age-diverse groups of no less than seven individuals. These recommendations are rooted in the idea that captive chimpanzee groups should be modeled after free-ranging, wild, fission-fusion chimpanzee societies. However, captive chimpanzees do not face the environmental pressures faced by wild chimpanzees, including food scarcity, inter-group competition, and predation. As such, it has been posited that wild, natural conditions may not be the most relevant metric for defining optimal captive chimpanzee group sizes and compositions. Additionally, captive housing poses a set of restrictions on group sizes and compositions, including the need to balance large, multi-male groups with space per animal limitations and intra-group aggression. In the present study, we examined the behavioral effects of group size, within-group age range, and percentage of males in the group. We collected 713 hr of focal animal samples across 120 captive chimpanzees housed in social groups of 4-10 individuals using a 58-behavior ethogram. Chimpanzees housed in groups with a large age range exhibited less inactivity and more locomotion than chimpanzees housed in groups with smaller age ranges. Additionally, chimpanzees in groups of ≥7 with less than half males showed the highest levels of locomotion. Lastly, chimpanzees in groups of ≥7 with at least half males showed the highest levels of affiliation. There were no other significant differences in behavior as a function of these variables or their interactions. These findings lend some support to the existing group size and composition recommendations, providing empirical evidence that there may be certain advantages to housing captive chimpanzees in larger groups with a more diverse age range and/or more males. These results also have practical implications for behavioral management programs across captive settings.
美国国立卫生研究院和动物园与水族馆协会建议，圈养的黑猩猩应生活在不少于 7 只个体组成的、多雄多雌、年龄多样化的群体中。这些建议的依据是，圈养黑猩猩群体应该以自由放养、野生、裂变融合的黑猩猩社会为模型。然而，圈养的黑猩猩不会面临野生黑猩猩所面临的环境压力，包括食物短缺、群体间竞争和捕食。因此，有人提出，野生的自然条件可能不是定义最佳圈养黑猩猩群体大小和组成的最相关指标。此外，圈养环境对群体大小和组成提出了一系列限制，包括需要平衡大型多雄群体与动物个体空间限制和群体内攻击。在本研究中，我们研究了群体大小、群体内年龄范围和群体中雄性比例对行为的影响。我们使用 58 种行为行为图收集了 120 只生活在 4-10 只个体组成的社会群体中的 120 只圈养黑猩猩的 713 小时焦点动物样本。与生活在年龄范围较小的群体中的黑猩猩相比，生活在年龄范围较大的群体中的黑猩猩的不活动和运动行为较少。此外，群体中雄性比例低于一半的黑猩猩活动水平最高。最后，群体中雄性比例至少一半的黑猩猩的依附行为水平最高。这些变量及其相互作用对行为没有其他显著影响。这些发现为现有的群体大小和组成建议提供了一些支持，为在更大的群体中、年龄范围更广泛和/或雄性比例更高的情况下饲养圈养黑猩猩可能存在某些优势提供了实证证据。这些结果还对圈养环境中的行为管理计划具有实际意义。
