Seeking the elusive Pacific bumble bee

Washington state has become the first US state to develop a statewide strategy to conserve bumble bees, focusing on eight state and federally recognized bumble bee species.

“We collectively saw (those species) as a shared priority and wanted to identify things we could do,” said Taylor Cotten, who manages conservation assessments for the state wildlife department and partnered with the Xerces Society and federal agencies to develop the strategy. 

About 1,200 community scientists worked for three years to map the bumble bees of Washington, Oregon and Idaho, starting in 2018, as part of a collaborative community science effort,  the Pacific Northwest Bumble Bee Atlas.

That data helped Washington state identify priority areas for conservation of the eight species. The document outlines regions of high priority for conservation — a horseshoe around the Columbia Plateau; the swath of lowlands from Portland to Puget Sound. It also outlines protective measures, like timing mowing and prescribed burns around nesting periods and planting the specific flowers that bees need.

Unlike honey bees, bumblebees don’t overwinter in hives or make honey. Instead, just the queens survive the cold months. In the spring, they emerge from often solitary nests and begin collecting pollen and reproducing. As the summer progresses, the queen stays in the colony, produces worker bees and grows the colony.

PNW Bumblebee Atlas project

Bumble bees are excellent pollinators of many crops. They are able to fly in cooler temperatures and lower light levels than many other bees, and they perform a behavior called “buzz pollination”, which some plants including tomatoes, peppers and cranberries require. The bee grabs the pollen producing structure of the flower in her jaws and vibrates her wing musculature causing vibrations that dislodge pollen that would have otherwise remained trapped in the flower’s anthers. 

Prior to 1998, the western bumble bee was common and widespread throughout the western US and western Canada. Of the 250 global species of bumble bees, nearly 30 are in the Pacific Northwest. But since 1998, there has been a drastic decline throughout some areas of its former range. While viable populations still exist in Alaska and east of the Cascades in the Canadian and US Rocky Mountains, the once common populations of central California, Oregon, Washington and southern British Columbia have largely disappeared. 

While factors leading to declines in bumble bee populations are not fully understood, contributing factors include habitat loss and fragmentation, impacts from pesticides, exposure to pathogens, competition from managed bees, and climate change. 

“The data that we had prior to this project, it’s basically just a bunch of collectors that have gone out and collected insects, killed them, and put them on pins,” said Rich Hatfield, the biologist who started the Atlas program at the nonprofit Xerces Society for Invertebrate Conservation. Dead specimens reveal few of the details that matter for conservation: What do they eat? Where do queens spend the winter? Why is this meadow full of voz and nevadensis, and yet the once-ubiquitous Western bumblebee — Bombus occidentalis — hasn’t been seen here in two decades? There aren’t enough scientists to capture the data, Hatfield said. Volunteers help fill the gaps.

As well as working on the Atlas in partnership with the US Forest Service, Bureau of Land Management, US Fish and Wildlife Service, and Washington Department of Fish and Wildlife, the Xerces Society has worked to increase pollinator habitat through the Xerces Society Habitat Kit Program – a partnership between Xerces, local residents, and native-plant nurseries.

PNW BumbleBee Atlas

The kits offer regionally appropriate plant materials grown to order by nurseries and supplied to community partners who provide the time, labour, and land. The habitat kits not only help people plant and nurture habitats that support pollinators, but they also remove financial barriers for groups and individuals who want to help.

Since 2019, California habitat kits enabled 115 projects, adding 106,000 plants that support pollinators. In the spring of 2021, Xerces distributed 46 kits in the Northeast—nearly 36,000 native plants—to agencies, conservation districts, nonprofit organizations, nature centers, community groups, Bee City USA and Bee Campus USA affiliates, and other organizations across nine states. In 2021 Xerces distributed 350 kits (11,500 plants) along the Santa Fe Pollinator Trail, a project developed with local agencies and nonprofits to create connected, climate-resilient pollinator habitat across the urban landscape. 

The US alone grows more than 100 crops that either need or benefit from pollinators, and the economic value of these native pollinators is estimated at $3 billion per year. 

Pollinators are responsible for one in three bites of food humans consume and provide billions of dollars in free pollination services.

“It’s really important for us as humans to study these species systems for animals that are the little guys that make the world go around,” said Ann Potter of the Washington Department of Fish and Wildlife, one of the entities in three states participating in the three-year Pacific Northwest Bumble Bee Atlas project.


To protect wild bumblebees, people have to find them first High Country News, Sep. 25, 2023

Washington State Becomes First To Adopt A Statewide Strategy To Protect Bumble BeesBee City USA, Feb. 23, 2023

Strategy to Protect State and Federally Recognized Bumble Bee Species of Conservation Concern. Washington State

Volunteers scatter to help Pacific NW bumblebee. Seattle Times, Jun.17, 2018