Not since the 1990s had the buzz of the white-bottomed Western Bumble Bee (Bombus occidentalis) been heard in Washington State. But last week at a park in Brier, just northeast of Seattle, a group of bee enthusiasts and biologists from the University of Washington documented the first official, confirmed B. occidentalis sighting in two decades!
Will Peterman snapped this unmistakable photo of a Western Bumble Bee with its telltake white rump.
Among the bee hunters that afternoon was Lisa Hannon, an NSF Graduate Fellow with the School of Environmental and Forest Sciences who’s currently researching how landscape factors and farmer practices impact parasitoid wasp communities (important for integrated pest management). Hannon had received a call a couple weeks ago from Will Peterman, a writer, photographer and bee expert in Seattle, to join him in trying to spot a Western Bumble Bee.
Peterman was following up on a year-old possible sighting that a local homeowner had logged with the Xerces Society as part of a citizen science initiative. Hannon’s lab mate, Hillary Burgess, was working on her Master’s at the time, and she was involved in that initial sighting. As part of her thesis project, “Local and Landscape-Level Influences of Bee Abundance and Diversity in Residential Gardens,” Burgess worked with landowners across King and Snohomish counties to keep detailed visitation logs regarding the pollinators visiting their gardens. The homeowner who spotted the bees was collecting survey data for her.
Now it was time to see if the bees were still there.
“On the day I searched, we hit pay dirt after four hours of scouring blackberry brambles,” says Hannon. They took photos of two or three queen bees, and then a second group of UW students returned on Sunday and reconfirmed at least two queen bees. This discovery has stoked hopes among bee lovers and biologists that the species, which is a crucial pollinator for many plants, might be making a comeback in the area (the Seattle Times ran a story about the exciting finding on July 14, as did an NPR program in California on July 18).
Lisa Hannon doing field work in Costa Rica.
B. occidentalis was once one of the most common bumble bees found on the West Coast, says Hannon, with a range extending from Alaska down to California, and east to the Rocky Mountains. The Xerces Society—a nonprofit that protects wildlife through the conservation of invertebrates and their habitat—considers this native species imperiled due to scattered populations and steep declines, among other factors. Currently, remnant populations can be found in the northern or eastern-most areas of their historical range, but colonies from southern British Columbia to central California are almost nonexistent.
Also along for the bee-spotting adventure was Evan Sugden, an adjunct professor with the UW Department of Biology, as well as several UW graduate students and a couple undergrads who were taking Sugden’s summer bee-keeping course.
“Normally, I chase bees and wasps in high mountain Costa Rican coffee farms and cloud forests,” says Hannon, “so it was a real treat to be able to work close to home!”
Photos: Western Bumble Bee © Will Peterman; Lisa Hannon in Costa Rica © Lisa Hannon.