A beefy, fuzzy black and yellow bumble bee nectars on a cluster of spikey pink milkweed flowers.

Xerces Society Files ESA Petition To Protect Morrison Bumble Bee

By Saff Killingsworth

To secure protections for an imperiled pollinator, the Xerces Society has submitted a petition for the listing of Morrison bumble bee (Bombus morrisoni) as an endangered species under the federal Endangered Species Act. An endangered listing will protect this species from activities that could cause it to go extinct, and will allow for additional conservation measures to protect the species across its range.

Assessed as vulnerable in 2015 on the IUCN Red List of Threatened Species (a non-regulatory designation separate from the federal Endangered Species Act), recent analyses of Morrison bumble bee show that the species has continued to decline in the intervening years. In the last 10 years, its relative abundance has declined by 74%, and the bee persists in 66% less area than it did historically. 

Morrison bumble bee visiting showy milkweed flowers in Nevada
We hope the U.S. Fish and Wildlife Service will act to protect Morrison bumble bee. (Photo: Leif Richardson/Xerces Society.) 

Morrison bumble bee faces multiple threats, uneven protection in the western US

The species’ historic range includes much of the western US, and can be found in a variety of habitats including grasslands, sagebrush steppe, and woodland edges. It faces multiple ongoing threats across its range, including habitat loss and degradation, effects of climate change, and exposure to pesticides and diseases. An ESA listing would protect Morrison bumble bees by addressing the threats they are facing, and ensuring regulatory mechanisms – which are currently lacking – are in place to protect the species. Federal protection is especially important for Morrison bumble bee because it occurs in several states in which the wildlife agency lacks management authority over insects, and thus, these states are unable to address the conservation needs of this bee.

Securing this bee will not only protect its intrinsic value; it also likely plays an important role in the continued health of the diverse ecosystems that define the western US. Many native ecosystems, including the deserts of the Southwest and the grasslands and shrublands of the Great Basin and interior Pacific Northwest, rely upon this charismatic pollinator. Additionally, bumble bees play a key role in supporting the production of many crops like tomatoes, peppers, melon, squash, and cotton. Conserving a diversity of native pollinators within the US is paramount to maintaining the country’s natural heritage and food security.

An ESA listing would both help safeguard the crucial pollination role this species plays in agriculture and ecosystems, and preserve a component of the biodiversity that is vital to ecosystem stability. An increased investment in pollinator habitat, along with protection from insecticides and pathogens, will be instrumental in preventing the extinction of the Morrison bumble bee. 

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Saff Killingsworth

Saff joined Xerces in 2022 as an endangered species conservation biologist. She coordinates the Wild Bee Initiative, working with researchers and land managers to assess the status of wild bees in the western U.S. and address their conservation needs. She also works to advance conservation of butterflies and fireflies in Arizona.

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