D3218: Modeling habitat suitability for the endangered rusty patched bumble bee (Bombus affinis): Insights for conservation and management

The rusty patched bumble bee (Bombus affinis) faces significant conservation challenges as an endangered species, particularly given the lack knowledge on its primary habitat. To estimate the current distribution and predict environmentally suitable habitats, we developed and tested a Presence-only model based on >1,000 Bombus affinis individuals identified throughout the mid-west (concentrated in Illinois and Iowa). The habitat distribution and detection probabilities were used to develop, and validated by, a spatially random field survey, which incorporated representative ecologic habitat variables and deliberate survey effort requirements across its range. By surveying multiple locations within across the bees’ potential range, we assessed the efficacy of our model in capturing seasonal variations and landscape influences on detection probability. A cross-correlation was performed to assess the variables and respective thresholds with the new field data. The final model indicates habitat preference is restricted to specific geographic regions across the study area. Our findings also highlight the importance of accounting for predictive factors such as proximity to forest edge, distance from water, and habitat quality in bumble bee monitoring efforts. Our models provide valuable insights for the conservation and management of B. affinis and other bumble bee species of concern