Threading the needle: spatial constraints sharpen visual sensitivity in honeybees

Navigating dense clutter requires honeybees to make rapid visual decisions to identify the best route. How they resolve perceptual inputs to choose a passage from multiple options is an open question. We challenged freely flying bees to choose between taller and shorter apertures across four height-difference ratios at three spatial scales. Bees chose the taller aperture in all tests, but precision depended on absolute aperture size. 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, the bees' choices were not uniformly sensitive across aperture size scales. Bees displayed greater sensitivity at the smallest spatial scale, where the likelihood of collisions is larger. This deviation in behaviour with absolute aperture size suggests a dynamic risk-cost trade-off. Bees appear to prioritize costly, high-acuity inspections only when confronted with critical physical constraints in the environment, and relax this vigilance at larger, safer scales to conserve energy.