Within-species variation in pollinator behavior is widely observed, but itscauses have been minimally investigated. Pollinator sex is associated with large differ-ences in behavior that may lead to predictable differences in flower foraging, but thisexpectation has not been explicitly tested. We investigate sex-associated differences innectar-foraging behavior of the hawkmothHyles lineata, using pollen on the proboscisas a proxy for flower visitation. We tested two predictions emerging from the literature:(1) the sexes differ in the flower species they visit, (2) females are more specialized inflower choice. We also examined potential drivers underlying these predictions by per-forming field and laboratory experiments to test whether males (3) switch among flowerspecies more frequently, or (4) fly farther and therefore encounter more species than fe-males. Consistent with prediction (1), pollen load composition differed between the sexes,indicative of visitation differences. Contrary to prediction (2), females consistently car-ried more species-rich pollen loads than males. (3) Both sexes switched between flowerspecies at similar rates, suggesting that differences in floral fidelity are unlikely to explainwhy females are less specialized than males. (4) Males flew longer distances than females;coupled with larger between-site differences in pollen composition for females, this resultsuggests that sex differences in mobility influence foraging, and that females may foragemore frequently and in smaller areas than males. Together, our results demonstrate thatsex-associated foraging differences can be large and consistent over time, and highlightthe importance of sex as a driver of variation in pollinator behavior.

Data collection details in the associated article