Pacific Southwest RegionCalifornia, Nevada and Klamath Basin
Plight of the bumblebees
The buzz on these important pollinators
Franklin’s bumblebee, Bombus franklini, on a California poppy has the narrowest range of any bumblebee in the U.S. and possibly the world. Experts hold out hope that this rare species will be found in the wild again. Photo courtesy of Pete Schroeder
By Susan Sawyer
June 25, 2021
When the subject of bees comes up, thoughts often range from finding the closest epi-pen to visions of sweet golden nectar slowly dripping from a bear or beehive-shaped bottle.
Two bumblebee species – a yellow-faced (Bombus vosnesenskii) on left and Franklin’s on right – share a lupine at Mt. Ashland, Oregon. Bumblebees use a buzz technique to gather pollen by vibrating their wing muscles inside the flower. Credit: Brendan White/USFWS
There are over 3,600 bee species native to the U.S. and Canada, yet none of them produce honey and many do not sting. They do, however, play crucial roles in local, wild ecosystems as pollinators, helping native plants and wildlife flourish. This diverse list includes wood-dwelling carpenter bees, nocturnal sweat bees, colony-commandeering cuckoo bees and 49 known species of bumblebees in the U.S.
While non-native honeybees got a lot of press in the last decade because of “colony collapse syndrome,” they are not the only pollinators in trouble. In fact, native bumblebees have been facing alarming declines across the country. The U.S. Fish and Wildlife Service recognizes the urgent need for pollinator conservation and is developing and reinforcing conservation partnerships across the country to improve habitat and health for bumblebees and all pollinators.
In Yreka, California, Anne Loggins, a biologist with the Service’s Yreka Fish and Wildlife Office, noted that threats to bumblebee survival, such as loss of floral resources, are as diverse as the species themselves.
“Agricultural monocultures, flowers that only bloom for a few weeks, have replaced meadows full of native plants producing nectar and pollen throughout the growing season,” said Loggins. “Human activities have also reduced the availability of bee nesting and overwintering habitats and their connectivity to foraging locations.”
Threats to bumblebees include loss of habitat such as this lush meadow where bright native flowers bloom in summer. The Yreka office participates in annual bee surveys in these habitats to gather data on declining pollinator species. Credit: Jeff Everett/USFWS
In addition, neonicotinoid pesticides, when widely used, are particularly harmful to bees.
“The chemicals are absorbed into the plant and ingested by the bees through the pollen and nectar they collect,” said Loggins. “While not instantly fatal, the neurotoxins impair the bees’ navigational system and foraging efficiency, ultimately decreasing the number of new queens produced the next year.”
Other threats to bumblebees include competition with non-native bees, climate change, parasites, wildfire and disease. Together, these drive bumblebee populations down, with potentially severe impacts to native ecosystems and the agriculture industry.
The buzz on bumblebees
A newly emerged white-shouldered bumblebee queen (Bombus appositus) takes a moment after being released during a field survey in Jackson County, Oregon. Over 25 species of bumblebees occur within the Klamath Basin, many found in high mountain meadows. Credit: Anne Loggins/USFWS
Bumblebees are perhaps the most charismatic of all bee species: they’re fuzzy, colorful and non-aggressive. And they’re one of the few insects to inspire a frenetic symphonic interlude composed by Rimsky-Korsakov in 1900 that was “intended to musically evoke the seemingly chaotic and rapidly changing flying pattern of a bumblebee.”
Their musical talents being questionable, bumblebees do employ a unique sound technique known as “buzz pollination” from which they get their name. This enables them to efficiently pollinate crops such as tomatoes, clover, cranberries and blueberries. The bee enters a flower and vibrates its wing muscles - or buzzes - causing pollen grains to fall onto the bee. Buzz pollination is nearly 800 times more efficient than pollination by honeybees and is the only way some plants will let loose their precious pollen.
Unlike honeybees that rely on stored honey to sustain colonies in winter, bumblebees only live one season. Each spring, a bumblebee queen emerges from her overwintering burrow or nest site, and in the ultimate single-mom act, deposits, incubates and feeds several hundred female worker bees. These workers then help care for new generations of queens and males to mate with them. After mating, the new queens burrow underground for the winter and the original queen and colony dies.
According to the Xerces Society, at least four species of formerly common North American bumblebees have experienced catastrophic declines over the past decade – two of them are on the brink of extinction. The International Union for Conservation of Nature reports that 28% of bumblebees in the U.S., Canada and Mexico are listed in their Threatened Category.
“The Service is especially concerned about the continued survival of species such as the western, Suckley’s cuckoo and Franklin’s bumblebee,” said Loggins. “The Franklin’s hasn’t been seen in 15 years, which factored into its consideration for listing as endangered under the Endangered Species Act.”
Franklin’s bumblebee: To bee or not
Renown entomologist Dr. Robbin Thorp, pictured here on one of his last surveys for native bees in Southern Oregon. Thorp was the last person to observe this species in the wild in 2006 and was instrumental in proposing the species for protection as endangered under the ESA. Photo courtesy of Rich Hatfield
Franklin’s bumblebee (Bombus franklini), was last seen on August 9, 2006 by Dr. Robbin Thorp, emeritus professor of entomology at University of California, Davis. Thorp was surveying on Mt. Ashland in Southern Oregon when he observed a single worker bee on a wildflower. Three years prior, he spotted the same species in roughly the same area where it had once been common.
“August 9th,” Thorp recalled in a 2013 interview. “I’ve got that day indelibly emblazoned in my mind.”
The Franklin’s limited range gives it the dubious distinction of having the narrowest distribution of any bumblebee in North America and possibly the world: 190 miles from Southern Oregon to Northern California, and 70 miles from the West Coast east to the Sierra-Cascade Ranges.
Bumblebees like the Franklin's are classified as “generalist foragers,” meaning they aren’t picky where they get their pollen; any wildflower will do. Their colonies may be limited by the abundance of rodent burrows and undisturbed clumped grasslands used for nest sites.
Unfortunately, Thorp, who had been keeping tabs on the species since the late 1960s, passed away in 2019 without ever seeing another Franklin’s bumblebee in the wild. In 1998, the Service, U.S. Forest Service, and Bureau of Land Management supported an intensive monitoring project to determine whether the bee should be listed as an endangered species, in part because of its narrow range. The Service expects to make a final listing decision for the bee this year.
An illustration depicting the annual life cycle of a bumblebee. A queen emerges in the spring from her winter burrow, deposits hundreds of eggs that hatch into female workers who care for subsequent generations. They are most active in summer collecting pollen and nectar, then new queens mate in the fall and overwinter underground while the original queen and colony dies. Credit: Anne Loggins/USFWS
The Yreka office continues to participate in annual bumblebee surveys in hopes the elusive Franklin’s is found buzzing around and Thorp’s efforts to protect this species were not in vain.
The Service will also continue to collaborate with federal partners and scientists on bumblebee research and genetics projects and support the work of bumblebee mapping efforts by the Oregon Bee Atlas and the Pacific Northwest Bumble Bee Atlas.
“Protecting native bees ensures our native plants, gardens and crops will continue to have an adequate supply of pollinators,” said Loggins. “Through further research and action, we can recover these declining species and ensure they continue to serve as a crucial link between pollen and plants.”
Want to help bee conservation? Try these ideas:
- Build pollinator-friendly native plant gardens in your yard or community that provide nesting cover and flower resources all season long
- Use alternative non-toxic pest management strategies
- Ensure purchased plants and seeds are neonicotinoid-free
- Encourage others to learn about threats to pollinators and support native bee conservation
- Become a citizen scientist and help with pollinator surveys to learn more about local bee populations: Bumblebee Watch
- For more: fws.gov/pollinators
About the writer...
Susan Sawyer is the Klamath Basin public affairs officer, covering the Klamath Basin National Wildlife Refuge Complex, Klamath Falls and Yreka Fish and Wildlife Offices. She was raised in the California desert gaining a deep appreciation of the outdoors on family vacations to the Pacific coast, Sierras and Redwood forests.
She has worked in Arizona, Nevada, Montana, Idaho and now Oregon, where she spends her free time landscaping for wildlife, continuing to learn from and about nature and spoiling her animals.
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