Threading the needle: Spatial constraints sharpen visual sensitivity in honeybees

Navigating dense clutter requires honeybees to execute rapid visuomotor comparisons to identify the best route. How they resolve perceptual inputs to make a passage choice from multiple options is an open question. We studied this in a free flying paradigm where bees were challenged to choose between a taller and shorter aperture with varying height difference. We monitored choice across four height difference ratios at three spatial scales. Bees chose the taller aperture in all tests, but the precision of these choices depended heavily on the absolute size of the gap. For each size scale of aperture pairs, psychometric modelling revealed that when making a choice bees generally evaluate the relative height difference, conforming to Weber's law. However, bees' choices were non-uniformly sensitive across aperture size scales. Bees had greater sensitivity at the smallest spatial scale, where the likelihood of collision danger is larger. This deviation in behaviour due to absolute aperture size suggests a dynamic risk-cost trade-off. Bees appear to prioritise costly, high-acuity inspections only when imposed by critical physical constraints of the environment, relaxing this vigilance at safer, larger scales to conserve energy.