Department of Anthropology, California State University Sacramento, Sacramento, California, USA.
Department of Anthropology, Stony Brook University, Stony Brook, New York, USA.
Am J Biol Anthropol. 2023 Jun;181(2):296-311. doi: 10.1002/ajpa.24743. Epub 2023 Apr 8.
Long-term home range stability presumably emerges because familiarity with an area improves fitness through increased foraging efficiency, reduced predation risk, or reduced costs of intergroup aggression. While the use of spatial memory by primates has been widely demonstrated, few studies have examined whether long-term space use creates opportunities for interannual reuse of spatial knowledge. Here we examine the ranging behavior of western gorillas (Gorilla gorilla) to assess the degree of long-term site fidelity and the foraging consequences of reuse of space.
We measured interannual home range overlap over a 10-year period for a single group of gorillas at the Mondika Research Center, using both grid-based and kernel density estimation. By plotting the total area used over time, we identified periods of home-range stability and expansion. We compared foraging and ranging behavior in familiar versus unfamiliar areas, considering fruit trees visited, dietary diversity, and daily path length, to determine whether the lack of spatial knowledge in unfamiliar areas was associated with foraging costs.
Average interannual home range overlap by the group remained high throughout the study. During periods of home range expansion, daily path lengths increased but not the number of fruit trees visited, suggesting that reduced familiarity with the area led to decreased foraging efficiency because individuals lacked prior knowledge of where to find resources.
Western gorillas at Mondika exhibit long-term home range stability, presumably reflecting a strategy that relies on the use of spatial memory to increase foraging efficiency that is favored by their reliance on ephemeral fruit resources.
长期的家域稳定性可能是由于对一个地区的熟悉程度提高了觅食效率、降低了被捕食的风险或减少了群体间攻击的成本，从而提高了适应性。虽然灵长类动物使用空间记忆已经得到了广泛的证明，但很少有研究探讨长期的空间使用是否为空间知识的跨年度重复使用创造了机会。在这里，我们研究了西部大猩猩（Gorilla gorilla）的活动范围，以评估长期的栖息地忠诚度以及空间重复使用的觅食后果。
我们使用基于网格和核密度估计的方法，在蒙迪卡研究中心对一个大猩猩群体进行了为期 10 年的年度家域重叠测量。通过绘制随时间变化的总使用面积，我们确定了家域稳定和扩展的时期。我们比较了熟悉和不熟悉地区的觅食和活动范围行为，考虑了访问的果树、饮食多样性和每日路径长度，以确定在不熟悉地区缺乏空间知识是否与觅食成本有关。
整个研究期间，该群体的年度家域重叠平均值保持较高水平。在家域扩展期间，每日路径长度增加，但访问的果树数量没有增加，这表明对该地区的熟悉程度降低导致觅食效率降低，因为个体缺乏对在哪里找到资源的先验知识。
蒙迪卡的西部大猩猩表现出长期的家域稳定性，这可能反映了一种依赖于空间记忆的觅食策略，这种策略提高了觅食效率，这是由它们对短暂的水果资源的依赖所决定的。
