A hierarchical approach for finding undiscovered populations of an endangered bumble bee

Scientific Reports
By: , and 

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Abstract

Understanding the distributions of rare species is necessary to guide monitoring and inform species recovery efforts. The rusty patched bumble bee (RPBB; Bombus affinis, Cresson) is an endangered species with an extant, known distribution centered around urban areas of the Midwestern United States. We tested a novel approach for finding undocumented RPBBs outside of urban centers and estimated the species occurrence at two scales that are relevant to management. We confirmed presence of RPBBs at 54% of the sampled 100 km2 grid cells where the species was previously undocumented, expanding the species’ known distribution by 5700 km2. After accounting for imperfect detection, our occupancy model estimated the number of occupied grid cells was 67 of 105 sampled grids, suggesting our methods were effective for finding undiscovered RPBB sites. Occupancy within 100 km2 grids was positively related to the number of occupied neighboring units but was not related to the area of developed land within 100km2 grid cells or smaller subunits (i.e. 3.14 ha patches or roadside transects). We highlight the utility of our approach for guiding future survey efforts by identifying an additional 145 grid cells where the occupancy status of RPBB is unknown but we predict a relatively high likelihood of RPBB occurrence. Our approach can be extended to find undiscovered RPBB sites in other areas and applied to other bee species where occurrence information is lacking outside of their core distribution.

Suggested Citation

Otto, C., Schrage, A.C., Lothspeich, A., Bailey, L., Smith, T., Planman, R., Cardin, J., Ellis, K.S., Dennis, B., and Grundel, R., 2026, A hierarchical approach for finding undiscovered populations of an endangered bumble bee: Scientific Reports, v. 16, 13759, 12 p., https://doi.org/10.1038/s41598-026-46861-8.

Study Area

Publication type Article
Publication Subtype Journal Article
Title A hierarchical approach for finding undiscovered populations of an endangered bumble bee
Series title Scientific Reports
DOI 10.1038/s41598-026-46861-8
Volume 16
Publication Date April 29, 2026
Year Published 2026
Language English
Publisher Nature
Contributing office(s) Great Lakes Science Center, Northern Prairie Wildlife Research Center
Description 13759, 12 p.
Country United States
State Illinois, Iowa. Minnesota, Wisconsin
Additional publication details