Rusty Patched Bumble Bee Critical Habitat

Rusty patched bumble bee range map.

USFWS listed the rusty patched bumble bee (Bombus affinis) as Endangered in 2017 due to a marked decrease in the range and size of populations across the Eastern U.S.  

As one of the first insect species to be listed under the Endangered Species Act, it offers an interesting case study for the way USFWS may approach other insects proposed for listing, including the Monarch butterfly, and numerous other bumble bee species.

From Xerces Society Listing Petition, 2016.

The listing petition states that "the rusty patched bumble bee probably needs floral resources to be located in relative close proximity to its nest sites, as studies of other bumble bee species indicate that they routinely forage within less than one kilometer from their nests ... although in some cases nearly two kilometers ... [It] is likely dependent upon woodland spring ephemeral flowers, since this bumble bee emerges early in the year and is associated with woodland habitats.....Rusty patched bumble bee queens are one of the earliest species to emerge, with observations as early as March and April."

Interestingly, rather than designate critical habitat based on the habitat needs of the species, USFWS chose to designate "High Potential" zones (e.g. critical habitat) as 1 mile buffers, and "Low Potential" zones as 4 mile buffers, around known (since 2006) sightings of the rusty patched bumble bee:

USFWS Map showing "High Potential" and "Low Potential" zones.  

Detail showing example 2x2 mile rusty patched bumble bee "High Priority" habitat in DeKalb, IL from USFWS map.  The buffered area seems to be based on a sighting at Prairie Park, and includes residential and industrial developments.  The only habitat in the area is within Prairie Park.  

USFWS has issued the guidance on whether consultation is required.  For vegetation management activities within the High Potential zones, the guidance provides the following test questions:

• Is there habitat for nesting, foraging, and/or overwintering for the rusty patched bumble bee in the action area or will the proposed action restore habitat for the species in the action area? 

• Will the action cause effects to vegetation in rusty patched bumble bee habitat in the High Potential Zone during the nesting period? Effects could occur as a result of mowing, cutting, grazing, prescribed fire, tree removal, spot-application of herbicide, tree clearing, and/or other activities. 

Based on this case example, it seems likely that USFWS will take a similar approach when listing other bumble bee species.  Specifically, it seems likely USFWS will only designate habitat immediately surrounding recently documented sightings, as opposed to using a general habitat model across the species' range.  Then, Section 7 consultation will be required for any activities that disturb habitat during the nesting period (i.e. growing season).

This seems to be the assumption underlying this Story Map, which shows small polygons of habitat as buffers around representative observations.  Note that the actual locations in this map are not accurate because the underlying observation data has been randomized to protect populations of rare species. 

This map of rusty patched bumble bee habitat around DeKalb, IL schematically shows the kind of habitat USFWS designated (i.e. buffered polygons around point observations) but does not show the accurate locations of the habitat because the data used for the map (GBIF) is randomized within 0.2 by 0.2 latitude/longitude rectangles.