Data from: Primates adjust movement strategies due to changing food availability

Animals are hypothesized to search their environments in predictable ways depending on the distribution of resources. Evenly distributed foods are thought to be best exploited with random Brownian movements; while foods that are patchy or unevenly distributed require non-Brownian strategies, such as Lévy walks. Thus, when food distribution changes due to seasonal variation, animals should show concomitant changes in their search strategies. We examined this issue in six monkey species from Africa and Mexico: three frugivores and three folivores. We hypothesized that the more patchily distributed fruit would result in frugivores showing more levy-like patterns of motion, while folivores, with their more homogenous food supply, would show Brownian patterns of motion. At least three and up to five of six species conformed to the overall movement pattern predicted by their primary dietary item. For folivorous black howler monkeys (Alouatta pigra), ursine colobus (Colobus vellerosus), and red colobus (Procolobus rufomitratus), Brownian movement was supported or could not be ruled-out. Two frugivores (spider monkeys, Ateles geoffroyi yucatanensis, and grey-cheeked mangabeys, Lophocebus albigena) showed Lévy walks, as predicted, but frugivorous vervet monkeys (Chlorocebus pygerythrus) showed a Brownian walk. Additionally, we test whether seasonal variation in the spatial availability of food support environmentally driven changes in movement patterns. Four of five species tested for seasonal variation showed adjustments in their search strategies between the rainy and dry seasons. This study provides support for the notion that food distribution determines search strategies and that animal movement patterns are flexible, mirroring changes in the environment.

已有假说表明，动物会依据资源的空间分布特征，以可预判的方式开展环境搜寻行为。学界认为，对于均匀分布的食物资源，采用随机布朗运动（Brownian movement）可实现最优觅食效率；而对于呈斑块状或非均匀分布的食物资源，则需采用非布朗运动策略，例如莱维行走（Lévy walk）。因此，当食物分布因季节波动发生改变时，动物的搜寻策略也应随之发生相应调整。
本研究针对来自非洲与墨西哥的6种猴科动物开展了相关检验，其中3种为食果动物（frugivore）、3种为食叶动物（folivore）。我们提出如下假说：由于果实的分布斑块性更强，食果动物的运动模式应更接近莱维行走；而食叶动物的食物资源分布相对均匀，其运动模式则应符合布朗运动特征。
6个物种中，至少3种、至多5种符合其主要食性对应的运动模式预测结果。对于食叶的黑吼猴（Alouatta pigra）、熊状疣猴（Colobus vellerosus）以及红疣猴（Procolobus rufomitratus），其运动模式符合布朗运动特征，或无法排除布朗运动的可能性。如预期所示，2种食果动物——蜘蛛猴（Ateles geoffroyi yucatanensis）与灰颊白眉猴（Lophocebus albigena）——呈现出莱维行走模式，但食果的黑长尾猴（Chlorocebus pygerythrus）却表现出布朗运动模式。
此外，本研究还检验了食物资源空间可获得性的季节变化是否会驱动动物运动模式随环境发生调整。在针对季节变化开展检验的5个物种中，有4个物种的搜寻策略在雨季与旱季之间发生了显著调整。
本研究结果支持以下核心观点：食物的空间分布格局决定了动物的搜寻策略，且动物的运动模式具有灵活性，可精准反映环境的动态变化。