Data from: A breath of fresh air in the foraging theory: the importance of wind for food size selection in a central place forager

Empirical data about food size carried by central place foragers does not often fit with the optimum predicted by classical foraging theory. Traditionally, biotic constraints such as predation risk and competition have been proposed to explain this inconsistency, leaving aside the possible role of abiotic factors. Here we documented how wind affects the load size of a central-place forager (leaf-cutting ants) through a mathematical model including the whole foraging process. The model showed that as wind speed at ground level increased from 0 to 2 km/h, load size decreased from 91 to 30 mm2, a prediction that agreed with empirical data from windy zones, highlighting the relevance of considering abiotic factors to predict foraging behavior. Furthermore, wind reduced the range of load sizes that workers should select to maintain a similar rate of food intake and decreased the foraging rate by ~70% when wind speed increased 1 km/h. These results suggest that wind could negatively reduce the fitness of colonies and limit the geographic distribution of leaf-cutting ants. The developed model offers a complementary explanation why load size in central place foragers may not fit theoretical predictions and could serve as basis to study the effects of other abiotic factors that influence foraging.

关于中心地觅食者（central place foragers）所携带食物尺寸的经验数据，往往与经典觅食理论（classical foraging theory）所预测的最优值不符。传统上，学界常以捕食风险（predation risk）、竞争（competition）等生物约束（biotic constraints）来解释这一不一致性，却忽略了非生物因子（abiotic factors）可能发挥的作用。本研究通过涵盖完整觅食过程的数学模型（mathematical model），揭示了风对中心地觅食者——切叶蚁（leaf-cutting ants）的负载量的影响。模型结果显示，当地面风速从0 km/h升至2 km/h时，负载量从91 mm²降至30 mm²，这一预测与多风区域的经验数据相符，凸显了在预测觅食行为时纳入非生物因子的重要性。此外，当风速每提升1 km/h，工蚁为维持相近食物摄入率（food intake）所应选择的负载量范围会缩小，且觅食速率（foraging rate）下降约70%。上述结果表明，风可能会对蚁群的适合度（fitness）产生负面影响，并限制切叶蚁的地理分布（geographic distribution）范围。本研究构建的模型为解释‘中心地觅食者的食物负载量为何与理论预测不符’提供了补充视角，同时也可作为研究其他影响觅食行为的非生物因子的基础框架。