Data from: Ecological context and the probability of mistakes underlie speed choice

1.Movement is fundamental to the ecology of animals, and an animal's choice of movement speed determines the duration, energetic costs, and probability of success of any given activity. It is often assumed that animals should use maximum speeds when escaping from predators, but an increasing number of studies find animals rarely move as fast as they can in nature because faster speeds come with a greater chance of mistakes. Mathematical modelling suggests that, when escaping predators, prey animals should optimise speeds to simultaneously outrun their pursuer and minimise their probability of slipping. This can be particularly important when running along narrow structures like branches. When foraging, however, animals should avoid moving at high speeds, which are often energetically costly and decrease the ability to detect food or predators.

2.In this study, we examined how trade-offs between speed and probability of slipping influenced the speed choice of wild antechinus (Antechinus mysticus) during escaping and foraging behaviours. We also examined how this trade-off affected foraging behaviour.

3.Antechinus ran significantly faster when escaping (1.207 ± 0.033 ms-1) than foraging (0.145 ± 0.002 ms-1), and slipped 37% more often during escapes. However, foraging antechinus still slipped frequently on narrow branches, despite running an order of magnitude more slowly than they did on wide branches. Furthermore, antechinus slipped at lower speeds when foraging than they did when escaping, suggesting that avoiding mistakes is less highly prioritized when foraging.

4.Antechinus visited the feeding station accessed by a wide branch more frequently (and ate more while there) compared with feeding stations accessed by narrow branches, even when those branches were 33% or 67% shorter. This suggests that foraging decisions may be based on potential limitations to speed and the probability of slipping over distance to cover.

5.Though activities such as running can be fundamental to animals’ fitness, a general framework to understand how animals select speeds in nature is still being developed. We test the assumption that animals choose running speeds to minimise their motor mistakes, and demonstrate the cost of mistakes is likely to be different across ecological and behavioural contexts.

1. 运动是动物生态学的核心基础，动物的运动速度选择直接决定了特定行为的持续时长、能量消耗与活动成功概率。学界普遍认为，动物在躲避天敌时会以最大速度行进，但越来越多的研究发现，自然界中动物极少达到自身极限速度，因为更高的速度伴随更高的失误概率。数学模型研究表明，在躲避天敌时，猎物应优化行进速度，以同时实现逃离追击者并降低滑倒概率的双重目标，这一点在沿树枝等狭窄结构行进时尤为关键。而在觅食过程中，动物则应避免高速移动——高速行进往往消耗大量能量，同时降低其发现食物与天敌的能力。
2. 本研究旨在探究速度与滑倒概率间的权衡如何影响野生袋鼩（Antechinus mysticus）在躲避天敌与觅食行为中的速度选择，并分析该权衡对其觅食行为的调控作用。
3. 实验结果显示，袋鼩在躲避天敌时的行进速度（1.207 ± 0.033 米/秒）显著高于觅食时的速度（0.145 ± 0.002 米/秒），且躲避过程中的滑倒概率比觅食时高出37%。不过，尽管觅食时的行进速度比在宽树枝上慢一个数量级，袋鼩在狭窄树枝上觅食时仍频繁滑倒。此外，袋鼩在觅食时的滑倒发生速度低于躲避天敌时，这表明在觅食场景中，避免失误的优先级相对更低。
4. 相较于通过狭窄树枝连通的取食站，袋鼩更频繁地造访宽树枝连通的取食站，且在该处的进食量也更高——即便后者的树枝长度比前者短33%或67%。这表明袋鼩的觅食决策或基于行进速度的潜在限制，以及在途经所需覆盖路径时的滑倒概率。
5. 尽管奔跑等行为对动物的生存适应度至关重要，但目前学界仍在构建用以阐释自然界中动物如何选择行进速度的通用理论框架。本研究验证了"动物选择行进速度以最小化运动失误"这一假设，并证明失误代价在不同生态与行为场景中存在显著差异。