Bandwagon effects in a floral market: Early pollinator acquisition offsets colour disadvantages in less attractive flowers

Abstract Flowers with striking colours or scents are often considered to have an advantage in the competition for pollinators. However, if pollinators copy others to avoid exploration costs in changing environments, less attractive flowers may benefit from acquiring early visitors by drawing more subsequent visitors and offsetting their colour disadvantage. Previous studies provide partial support for this view, but mostly focus on pollinator behaviour at small spatial scales rather than on plant benefits in the field. To investigate whether flowers benefit from acquiring early visitors in attracting subsequent pollinator visits, we conducted a semi‐outdoor experiment in a large flight arena designed to replicate the significant information‐gathering costs encountered in field conditions. By simulating a typical scenario where bumblebees are motivated to shift from a flower species with declining resource quality to newly blooming ones, we assessed the impact of early arrivals—mimicked by dead bees placed on flowers—on subsequent pollinator attraction. When there were no early arrivals, bees showed a preference of approximately 90% for one of the two new flower colours presented. However, when early arrivals were placed in one of the patches, bees were strongly attracted to the occupied patch as well as to the one with their innately preferred colour. Notably, when their innate colour preferences and the presence of early arrivals conflicted, the two factors either cancelled each other out or the preference was even slightly stronger for early arrivals. In other words, floral attractiveness was the primary cue when no other bees were present, whereas the late arrivals gave equal weight to early visitors. This shift in bees' foraging decisions may partly reflect changes in how they sample new floral options. Our results suggest that less attractive flowers may have a similar or even higher fitness than those with attractive colouration by gaining a head start in pollinator acquisition. This effect would be especially pronounced if the presence of conspecifics triggers a snowball effect on the choices of subsequent foragers. The use of social information by pollinators may thus represent an overlooked selective force driving the evolution of early flowers, highlighting a more multifaceted and dynamic role of pollinators in this process. Read the free Plain Language Summary for this article on the Journal blog.