Animal-pollinated plants depend on sequential pollinator visits to conspecifics for successful reproduction. Therefore, in co-flowering plant communities, the proportion of visits to a focal plant species in individual pollinator foraging bouts determines reproductive outcomes for that species. We investigated the factors determining bee visits to the plant Astragalus scaphoides within foraging bouts in a natural multispecies community in the northern Rocky Mountains. We found that both conspecific and heterospecific floral density influenced the proportion of visits to A. scaphoides during foraging bouts, but these effects of floral density differed among two abundant bee groups. Our field observations reject the null expectation that bees visit plant species in direct proportion to their relative floral densities. Bombus consistently visited A. scaphoides more than expected, while solitary bees of the genera Anthophora and Eucera exhibited a nonlinear response to floral density.
All Science Journal Classification (ASJC) codes
- Nature and Landscape Conservation
- floral density
- floral preference
- resource switching
- solitary bees