Project-specific bumble bee habitat quality assessment

The listing of Bombus affinis Cresson 1863 (Rusty Patched Bumble Bee; RPBB) in 2017 under the Endangered Species Act (ESA) created a regulatory need for assessment methods, in order to limit take of this species by construction and development. As the first social insect listed under the ESA, the listing of RPBB has required new methods for biological assessment. This species has a complex life cycle requiring a mosaic of different habitat types, with each life cycle stage facing unique challenges and threats. I have established a method for separately assessing habitats critical to each vulnerable life history stage, using a combination of aerial photography, GIS maps and target-specific ground survey efforts. This method identifies factors that may potentially limit bumble bee colony success in each stage and provides project planners with facts about physical structures or plant communities that may have elevated importance to bumble bees during certain seasonal windows. Previous efforts to assess bumble bee habitat considered landscape features thought to be linked to bumble bee colony success. This effort extends these methods to estimate project specific impacts of construction and development projects, necessary for Section 7 Consultation with the United States Fish and Wildlife Service (USFWS) under the ESA. •Systematic spatial assessment of landscape features linked to critical periods in the life history trajectory of a bumble bee colony across a season•Construction and development project proponents can approach USFWS consultation with quantitative estimates of the area of a project area classified by habitat types and qualities•Factors limiting bumble bee recovery may be inferred from the distribution and abundance of the constituent elements of quality bumble bee habitat.