What is the historical range of the Suckley’s cuckoo bumble bee?

The Suckley’s cuckoo bumble bee had a broad historical distribution across North America, stretching from the Yukon down to Arizona and as far east as Newfoundland. The species has been collected in various habitat types from 2 to 3,200 meters (6 to 10,500 feet) in elevation and has been documented in the following states: Arizona, California, Colorado, Idaho, Minnesota, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, Wyoming. 

When was the last confirmed sighting?

The last confirmed sighting of Suckley’s cuckoo bumble bee in the United States was 2016 in Oregon, although it is still found in some portions of its range in Canada, and there are many examples where other species have been rediscovered (e.g., Fender’s Blue Butterfly, recently reclassified to Threatened).

What’s causing the decline and why is this significant? 

Suckley’s cuckoo bumble bee a pollinator itself and is also an obligate social parasite that depends on social bumble bee hosts for survival and raising its young. The viability (e.g., ability to maintain populations in the wild over a biologically meaningful timeframe) of Suckley’s cuckoo bumble bee is therefore highly dependent on its host bumble bee species, many of which have also declined historically and are expected to continue to do so in the near-term. Suckley’s cuckoo bumble bee has declined due to the decline of its host species, pathogens, pesticides, habitat fragmentation and conversion, and climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change . 

What are some other bee species currently facing extinction? 

There have been multiple studies published since the mid-2010s showing that pollinator and bee populations in general are in decline. Franklin’s bumble bee, rusty patched bumble bee, and seven Hawaiian bee species are all currently listed as endangered. The statuses of the American bumble bee, western bumble bee, and southern plains bumble bee and others are currently under review to determine if they require the protections of the Endangered Species Act.

Citations:

Janousek et al 2023 Recent and future declines of a historically widespread pollinator linked to climate, land cover, and pesticides | PNAS

Cameron et al 2010Patterns of widespread decline in North American bumble bees | PNAS

Goulson et al 2015 Bee declines driven by combined stress from parasites, pesticides, and lack of flowers | Science

What does this announcement mean? 

Based on the best available science and commercial data, the Service is proposing to list Suckley’s cuckoo bumble bee as endangered under the Endangered Species Act. However, the Service has determined that designation of critical habitat is prudent but not determinable at this time due to lack of current data sufficient to perform required analyses.

What lead up to this announcement? 

The Service was petitioned April 23, 2020, by the Center for Biological Diversity to list Suckley’s cuckoo bumble bee as an endangered species and to designate critical habitat. On May 11, 2021, the Service announced in the Federal Register (86 FR 25833) that the petition presented substantial information indicating that this species may be warranted for listing and announced the initiation of a status review for the species. On April 22, 2022, the Center for Biological Diversity filed a complaint stating that the Service failed to meet the statutory deadline. On September 27, 2022, the Service agreed to submit a finding to the Federal Register by December 10, 2024. 

Why should people care about a parasitic bee like Suckley’s?

Suckley’s cuckoo bumble bee is an important indicator species for the health of pollinators and native floral communities. In addition, this bee’s parasitic nature is very unique among bees, with social parasites making up less than 1% of all bee species. They are different from brood parasites, which only attack the brood of their host, because social parasites rely on the entire colony. Female cuckoo bumble bees invade host bumble bee nests where they will often eliminate the host queen, destroy host eggs, and eject host larvae from the nest. Worker bees from the host species feed and provision the young of the parasite.

How can you help pollinators, including Suckley’s cuckoo bumble bee and its hosts? 

Protecting native bees helps ensure native plants, gardens, and crops will continue to have an adequate supply of pollinators. You can help by limiting the use of pesticides, promoting native floral communities, and provide shelter they need to survive the winter by putting the rake away and “leaving the leaves.”