Data from: Seasonal food scarcity prompts long-distance foraging by a wild social bee

Foraging is an essential process for mobile animals and its optimization serves as a foundational theory in ecology and evolution; however, drivers of foraging are rarely investigated across landscapes and seasons. Using a common bumble bee species from the Western US (Bombus vosnesenskii), we ask if seasonal decreases in food resources prompt changes in foraging behavior and space use. We employ a unique integration of population genetic tools and spatially-explicit foraging models to estimate foraging distances and rates of patch visitation for wild bumble bee colonies across three study regions and two seasons. By mapping the locations of 669 wild-caught individual foragers, we find substantial variation in colony-level foraging distances, often exhibiting a 60-fold difference within a study region. Our analysis of visitation rates indicates that foragers display a preference for high-cover destination patches and forage significantly further for these patches, but only in the summer, when landscape-level resources are low. Overall, these results indicate that an increasing proportion of long-distance foraging bouts take place in the summer. As pollinators, the foraging dynamics of wild bees are of urgent concern given the potential impacts of global change on their movement and services. The behavioral shift towards long-distance foraging with seasonal declines in food resources suggests a novel phenologically-directed approach to landscape-level pollinator conservation and increased evaluation of late-season floral resources.