Climate change winners and losers among North American bumble bees

Background/Question/Methods

Mounting evidence suggests that climate change, agricultural intensification, and disease are impacting bumble bee health and contributing to species' declines. Identifying how these factors impact insect communities at large spatial and temporal scales is difficult, partly because species may respond in different ways. Further, the necessary data must span large spatial and temporal scales, which usually means they comprise aggregated, presence-only records collected using numerous methods (e.g., diversity surveys, educational collections, standardized ecological surveys, haphazard collections). Here, we use occupancy models, which explicitly correct for biases in the species observation process, to quantify the effect of changes in temperature, precipitation, and floral resources on bumble bee site occupancy over the past 12 decades in North America.

Results/Conclusions

We find no evidence of genus-wide declines, but do find that occupancy is negatively correlated with temperature, but only weakly related to precipitation or floral resources. We also find that more species are likely to be climate change "losers" than "winners" and that this effect appears primarily associated with changing temperature. Importantly, all trends were highly species-specific, highlighting that genus or community-wide measures may not reflect diverse species-specific patterns that are critical in guiding allocation of conservation resources.