Data from: Risso' s dolphins plan foraging dives

Humans remember the past and use that information to plan future actions. Lab experiments that test memory for the location of food show that animals have a similar capability to act in anticipation of future needs, but less work has been done on animals foraging in the wild. We hypothesized that planning abilities are critical and common in breath-hold divers who adjust each dive to forage on prey varying in quality, location, and predictability within constraints of limited oxygen availability. We equipped Risso &' s dolphins with sound-and-motion-recording tags to reveal where they focus their attention through their externally observable echolocation and how they fine-tune search strategies in response to expected and observed prey distribution. The dolphins &' information was integrated with synoptic prey data obtained from echosounders on an underwater vehicle. At the start of the dives, whales adjusted their echolocation inspection ranges in ways that suggest planning to forage at a particular depth. Once entering a productive prey layer, dolphins reduced their search range comparable to the scale of patches within the layer, suggesting that they were using echolocation to select prey within the patch. On ascent, their search range increased, indicating that they decided to stop foraging within that layer and started searching for prey in shallower layers. Information about prey, learned throughout the dive, was used to plan foraging in the next dive. Our results demonstrated that planning for future dives was modulated by spatial memory derived from multi-modal prey sampling (echoic, visual, and capture) during earlier dives.

人类能够铭记过往经历，并依托这些信息规划未来行动。旨在测试动物食物位置记忆的实验室实验表明，动物具备类似的、为预判未来需求而采取行动的能力，但针对野生动物野外觅食行为的相关研究仍较为匮乏。我们提出假说：规划能力在屏气潜水动物中至关重要且普遍存在——这类动物需在氧气储量有限的约束条件下，调整每次潜水的行为，以捕食质量、位置和可预测性各不相同的猎物。我们为里氏海豚（Risso's dolphins）部署了声动记录标签（sound-and-motion-recording tags），通过其可被外部观测到的回声定位（echolocation）行为，解析其注意力聚焦的位置，并探究它们如何根据预期及实测的猎物分布情况，微调搜索策略。我们将海豚的相关数据与从水下航行器（underwater vehicle）搭载的回声测深仪（echosounders）获取的同步猎物观测数据进行整合。在潜水伊始，这些鲸类会调整其回声定位的探测范围，其调整模式暗示它们已规划好在特定深度开展觅食活动。一旦进入高产猎物层，海豚会将搜索范围缩小至与该层内猎物斑块尺度相当的水平，这表明它们正通过回声定位在斑块内筛选猎物。在上浮过程中，它们的搜索范围再度扩大，这意味着它们已决定终止该层内的觅食活动，并开始在更浅的水层中搜寻猎物。整个潜水过程中获取的猎物相关信息，会被用于规划下一次潜水的觅食行为。我们的研究结果表明，对未来潜水的规划，会受到此前潜水过程中通过多模态猎物采样（multi-modal prey sampling，含回声、视觉及捕获三种方式）所获得的空间记忆的调控。