Although navigating along a network of routes might constrain animal movement flexibility, it may be an energetically efficient strategy. Routinely using the same route allows for visually monitoring of food resources, which might reduce the cognitive load and as such facilitate the process of movement decision-making. Similarly, locating routes in areas that avoid costly landscape attributes will enhance their overall energy balance. In this study we determined the benefits of route navigation in an energy minimiser arboreal primate, the black howler monkey (Alouatta pigra). We monitored five neighbouring groups of black howler monkeys at Palenque National Park, Mexico from September 2016 through August 2017. We recorded the location of the focal group every 20 m and mapped all travel paths to establish a route network (N = 1528 travel bouts). We constructed linear mixed models to assess the influence of food resource distribution (N = 931 trees) and landscape attributes (slope, elevation and presence of canopy gaps) on the location of routes within a route network. The number of food trees that fell within the visual detection distance from the route network was higher (mean: 156.1 ± SD 44.9) than randomly simulated locations (mean: 121.9 ± SD 46.4). Similarly, the number of food trees found within the monkey’s visual range per meter travelled increased, on overage, 0.35 ± SE 0.04 trees/m with increasing use of the route. In addition, route segments used at least twice were more likely to occur with increasing density of food resources and decreasing presence of canopy gaps. Route segments used at least four times were more likely to occur in elevated areas within the home ranges but only under conditions of reduced visual access to food resources. Route navigation emerged as an efficient movement strategy in a group-living arboreal primate. Highly used route segments potentially increased visual access to food resources while avoiding energetically costly landscape features securing foraging success in a tropical rainforest.

中文翻译：

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新热带哺乳动物的树栖路线导航：与树木监测和景观属性相关的能量影响

虽然沿着路线网络导航可能会限制动物运动的灵活性，但它可能是一种能量有效的策略。常规使用相同的路线可以直观地监控食物资源，这可能会减少认知负荷，从而促进运动决策的过程。同样，在避免昂贵的景观属性的区域中定位路线将增强其整体能量平衡。在这项研究中，我们确定了路线导航对能量最小的树栖灵长类动物黑吼猴 (Alouatta pigra) 的好处。从 2016 年 9 月到 2017 年 8 月，我们在墨西哥帕伦克国家公园监测了五个相邻的黑吼猴群。我们每隔 20 m 记录一次焦点群的位置，并绘制所有旅行路径以建立路线网络（N = 1528 次旅行） . 我们构建了线性混合模型来评估食物资源分布（N = 931 棵树）和景观属性（坡度、海拔和树冠间隙的存在）对路线网络内路线位置的影响。落入路线网络视觉检测距离内的食物树数量（平均值：156.1 ± SD 44.9）高于随机模拟位置（平均值：121.9 ± SD 46.4）。同样，随着路线使用的增加，在猴子每米视线范围内发现的食物树数量增加了 0.35 ± SE 0.04 树/米。此外，随着食物资源密度的增加和树冠间隙的减少，使用至少两次的路线段更有可能发生。使用至少四次的路线段更有可能出现在家庭范围内的高地区域，但仅在视觉获取食物资源减少的情况下。在群居的树栖灵长类动物中，路线导航成为一种有效的运动策略。高度使用的路线段可能会增加对食物资源的视觉访问，同时避免在热带雨林中确保觅食成功的能源成本高昂的景观特征。