Assessing the stability and distribution of a newly discovered endangered bumble bee population in Northeastern Illinois

Many species of bumble bees (Bombus spp.) have been declining in abundance across North America. In the Midwest declines, including that of B. affinis, recently listed as a federally endangered species, are attributed to several factors including habitat loss. Native tallgrass prairies could be ideal areas for Bombus spp. communities to sustain populations, due to native floral resources. However, few studies have been done to determine this. Our objective was to determine the stability and consistency of B. affinis populations at Midewin National Tallgrass Prairie and to investigate whether Goose Lake Prairie, a nearby prairie remnant, provides a stable habitat that may be sources for B. affinis and other Bombus species of conservation concern in the region. We used nets to survey twelve 100m transects throughout both sites, representing three different habitat types; remnant prairie, restored prairie, and cattle pasture/other. B. affinis was not found at either habitat type, despite records of their presence from a previous year, however we did find several other species of conservation concern at very low numbers. We also found that the remnant prairie had greater species abundance and richness of Bombus species with two very common species, B. griseocollis and B. impatiens, being very common. With our findings we were able to determine that there are indeed habitat preferences among Bombus species, although we were unable to detect a habitat preference for species of conservation concern