Pollen richness and diversity
At the morphotype level, neither pollen richness, nor diversity varied between the two bee species, among periods, or sites (Table 3). At the family level, we observed a statistically significant interaction between the effects of period and bee species on pollen richness, and a statistically significant impact of both period and bee species on pollen diversity (Table 3). There is greater statistical power at the family relative to morphotype levels, due to the fewer number of families and greater sample size associated with each family. Bumble bees collected pollen from more plant families relative to honey bees in period one, while the opposite pattern was observed in period three (Fig. 3a). There were no statistically significant differences between bee species in periods two, four, or five (Fig. 3a). Overall, bumble bees collected pollen from (mean ± se) 4.26 ± 0.27 plant families, and 5.38 ± 0.35 plant morphotypes on a given day, while honey bees foraged for pollen on 3.39 ± 0.27 plant families, and 4.36 ± 0.33 plant morphotypes. Bumble bees collected more diverse pollen (mean ± se) (0.54 ± 0.03) relative to honey bees (0.33 ± 0.04) (Table 3). In addition, over both bee species, pollen diversity values were lower in period one compared to periods three, four, and five (Fig. 3b).