Competition within and between social groups determines access to resources and can be inferred from space use parameters that reflect depletion of food resources and competitive abilities of groups. Using location data from 1998 to 2017, we investigated within- and between-group competition in 12 groups of wild mountain gorillas (Gorilla beringei beringei). As within-group feeding competition is expected to increase with group size, an increase in group size is predicted to lead to an increase in the size of annual home ranges and core areas, but to a decrease in fidelity (reuse of an area). Due to asymmetries in competitive abilities, larger groups are expected to have higher exclusivity (degree of non-shared space) of annual home ranges and core areas than smaller groups. We found evidence of within-group feeding competition based on a positive relationship between group size and both annual home range and core area size as well as a negative relationship between group size and core area fidelity. Additionally, fidelity of core areas was lower than of home ranges. Between-group competition was inferred from a trend for groups with more members and more males to have more exclusive home ranges and core areas. Lastly, annual core areas were largely mutually exclusive. Our study suggests that non-territorial, group-living animals can have highly dynamic, long-term avoidance-based spacing patterns, both temporally and spatially, to maintain annual core area exclusivity among groups while concurrently shifting these areas annually within overlapping home ranges to avoid resource depletion. Despite ranging in larger home ranges and core areas, larger groups were able to maintain more exclusive ranges than smaller groups, suggesting a competitive advantage for larger groups in between-group competition in a non-territorial species. Together, these findings contribute to understanding how social animals make behavioral adjustments to mitigate the effects of intraspecific competition.

中文翻译：

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使用长期测距模式来评估野生山地大猩猩的组内和组间竞争。

社会群体内部和之间的竞争决定了对资源的获取，可以从反映粮食资源枯竭和群体竞争能力的空间使用参数中推断出来。利用1998年至2017年的位置数据，我们调查了12组野生山地大猩猩（Gorilla beringei beringei）的群体内和群体间竞争。由于组内饲养竞争预计会随着组规模的增加而增加，因此，预计组规模的增加会导致年度房屋范围和核心区域的规模增加，但保真度会降低（对区域的再利用）。由于竞争能力的不对称性，预计较大的群体将比较小的群体具有更高的年度房屋范围和核心区域排他性（非共享空间的程度）。我们基于组规模与年度家庭范围和核心区域尺寸之间的正相关关系，以及组规模与核心区域保真度之间的负相关关系，发现了组内饲养竞争的证据。此外，核心区域的保真度低于家庭范围。团体间竞争是从一种趋势开始的，这种趋势是拥有更多成员和更多男性的团体拥有更多专属住宅区和核心区域。最后，年度核心领域在很大程度上是相互排斥的。我们的研究表明，非领土，生活在群体中的动物可以在时间和空间上具有高度动态的，基于长期回避的间隔模式，以保持群体之间的年度核心区域独占性，同时将这些区域每年在重叠的家庭范围内转移到避免资源枯竭。尽管分布在较大的家园范围和核心区域内，但较大的群体仍比较小的群体保持更多的独占范围，这表明较大的群体在非领土物种的群体间竞争中具有竞争优势。总之，这些发现有助于理解社交动物如何进行行为调整以减轻种内竞争的影响。