At-Risk Bumble Bees

While all pollinators are facing significant threats, some bumble bee species are the most at-risk of extinction. Better monitoring of all species will allow us to determine which populations are growing, which are shrinking, and which may already be gone. An analysis led by the Xerces Society, and coordinated with the IUCN North American Bumble Bee Specialist Group, indicates that more than one-quarter of North American bumble bees are facing some degree of extinction risk. Read the profiles below to learn about bumble bee species that are currently most at-risk in North America and their IUCN Red List status.

Note: This list is intended to represent North American species of concern, and is not intended to represent a survey of threatened species globally.

Rusty Patched Bumble Bee (Bombus affinis)

Geographic Range: Historically common and broadly distributed in the Upper Midwest and Eastern North America.

IUCN Status: Critically Endangered

U.S. Endangered Species Act Status: Endangered

Profile: Bombus affinis has recently experienced serious declines in relative abundance, persistence and distribution across its range. Despite increased awareness and survey efforts for B. affinis, numerous regional studies have reported local extirpations and declines in this species, and range-wide studies have found relative abundance declines up to 95%, and range losses of 70 to 87% in recent years. Learn More

Read the Xerces Society Profile of this species and the IUCN Red List profile for more information

Photo: © Clay Bolt

Franklin’s Bumble Bee (Bombus franklini)

Geographic Range: Bombus franklini occurs only in the USA. It is found only from southern Oregon to northern California between the Coast and Sierra-Cascade Ranges, in Douglas, Jackson and Josephine and Siskiyou and Trinity counties in Oregon and California respectively.

IUCN Status: Critically Endangered

Profile: The population is currently decreasing drastically. Areas known or suspected to be inhabited by this species were surveyed annually over nine years, some more than once.  During the first three years, bees were observed at seven new sites (where this bee had not been recorded before) but as time went on this number decreased. The continued abundance of other bumblebees at these sites suggest that the habitat has not become uninhabitable. Read More

View the Xerces Society Profile of this species and the IUCN Red List profile for more information

Photo: USFWS / Brendan White

Western Bumble Bee (Bombus occidentalis)

Geographic Range: Historically broadly distributed in western North America. Bombus occidentalis occurs along the Pacific coast and western interior of North America, from Arizona, New Mexico and California, north through the Pacific Northwest and into Alaska. Eastward, the distribution stretches to the northwestern Great Plains and southern Saskatchewan.

IUCN Status: Vulnerable

Profile: Formerly common throughout much of its range, populations from central California to southern British Columbia and west of the Sierra-Cascade Ranges have declined sharply since the late 1990s. There have been significant range losses in these regions, particularly from lower elevation sites in California, western Oregon and western Washington. Read More

View the Xerces Society Profile of this species and the IUCN Red List profile for more information

Photo: © Diane Wilson

Yellow Banded Bumble Bee (Bombus terricola)

Geographic Range: Historically this species held a large range from Newfoundland and the northeastern U.S., south along higher elevations of the Appalachians, west through North Dakota and the Canadian Great Plains, across much of Saskatchewan and Alberta, west into British Columbia.

IUCN Status: Vulnerable

Profile: Numerous studies indicate that this species has declined, both regionally and locally, especially in the southern portion of its range.  A recent long-term study in the Northeastern United States examining historical changes in bees found that, although this species did not exhibit the rapid and drastic population declines seen in B. ashtoni, B. pensylvanicus, and B. affinis, it did exhibit significant declines in relative abundance across its northeastern U.S. range. In another study comparing current and historical distributions of eight bumble bee species in the United States using museum records and nationwide survey data, it was found that relative abundances of B. terricola had sharply declined in recent years, from 10% relative abundance to less than 1%, in comparison with codistributed speciesRead More

View the Xerces Society Profile of this species and the IUCN Red List profile for more information

Photo: The Xerces Society / Sarah Foltz Jordan

Obscure Bumble Bee (Bombus caliginosus)

Geographic Range: This species occurs along the Pacific Coast, from southern California to southern British Columbia, with scattered records from the east side of California’s Central Valley

IUCN Status: Vulnerable

Profile: Analyses suggest very high population decline range-wide, including range size reductions, persistence reductions, and relative abundance declines.  The level of population decline is difficult to ascertain, with more surveys  needed within this species’ historic range. This is because the species co-occurs with Bombus vosnesenskii (a very common bee that is difficult to discern from B. caliginosus in the field) which may lead many collectors/observers to mis-identify this species. Read More

Photo: projectnoah.org

Crotch Bumble Bee (Bombus crotchii)

Geographic Range: This species occurs primarily in California, including the Mediterranean region, Pacific Coast, Western Desert, Great Valley, and adjacent foothills through most of southwestern California. It has also been documented in southwest Nevada, near the California border.

IUCN Status: Endangered

Profile: Analysis suggests sharp declines in both relative abundance and persistence over the last ten years. This species was historically common in the Central Valley of California, but now appears to be absent from most of it, especially in the center of its historic range. Current range size relative to historic range: 74.67%.  Read More

Photo: bugguide.net

Yellow Bumble Bee (Bombus fervidus)

Geographic Range: This is a widespread species across much of the mid-latitudes of the continent, from the Canadian Maritimes and eastern United States, west through the Great Plains and southern Canada to the Pacific Coast and Western Desert.

IUCN Status: Vulnerable

Profile: A number of studies have demonstrated abundance and persistence declines in this species. Consistent with these studies, our analysis shows decline in relative abundance over the time period examined, as well as long term steady decline. If this species’ relative abundance continues to decline at the same rate, we project that the species will go extinct in the next 70 to 80 years. Read More

Photo: © Diane Wilson

Southern Plains Bumble Bee (Bombus fraternus)

Geographic Range: Bombus fraternus is found in the Eastern Temperate Forest region on the coastal plain of the southeastern United States from central Florida north to New Jersey, Ohio west throughout the United States Great Plains.

IUCN Status: Endangered

Profile: This North American species has exhibited declines in relative abundance across its range over the past decade. This species’ long-term downward trend in relative abundance is significant; if the same rate of decline continues, this species could potentially go extinct within 80-90 years. Read More

Photo: The Xerces Society / Jennifer Hopwood

Morrison Bumble Bee (Bombus morrisoni)

Geographic Range: This species occurs throughout the west from California east of the Sierra-Cascade Ranges to southern British Columbia; east to New Mexico, Texas, and north to western South Dakota. In addition, this species has been sporadically found west of the Sierra-Cascade crest in Oregon and California.

IUCN Status: Vulnerable

Profile: This western North American species has declined in relative abundance by 82.57% over the past ten years, and persistence declines have also been high (>70%). More research is needed to evaluate the status of this species throughout its range, especially eastern Oregon and Washington, and western Nevada. Overall, this species is uncommon, and appears to be declining in parts of its range. Read More

Photo: bugguide.net

American Bumble Bee (Bombus pennsylvanicus)

Geographic Range: Bombus pensylvanicus is widespread in the eastern U.S. and Great Plains regions, throughout the central U.S. and extreme southern Canada.  Though absent from much of the Mountain West, it is found in the Desert West and adjacent areas of California and Oregon.

IUCN Status: Vulnerable

Profile: Historically, Bombus pensylvanicus was among the broadest ranging bumblebees in North America. However, numerous studies indicate that this species has recently declined, both locally and regionally, especially in the northern parts of its range. Read More

Photo: The Xerces Society / Jennifer Hopwood

Variable Cuckoo Bumble Bee (Bombus variabilis)

Geographic Range: This species is found in the Eastern Temperate Forest and Great Plains region of the midwestern U.S., with scattered occurrences on the southeastern coastal plain, southern Texas, and southern Arizona, across Central America, Guatemala, and Mexico.

IUCN Status: Critically Endangered

Profile: This species is considered one of the rarest of all North American bumble bee species, having been collected only a few times in the past twenty years, and not at all in the last decade. Relative abundance has been consistently downward since the 1920s, reaching zero in the recent decade. Read More

Photo: discoverlife.org

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Working with experts in the IUCN Bumblebee Specialist Group, the Xerces Society has completed research to better understand the extinction risk of all North American bumble bees and has found that more than one-quarter of North America’s bumble bee fauna are at risk of extinction. Learn more about bumble bee species at risk in the US and Canada.

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