Many of us in California have never seen the Western bumble bee (Bombus occidentalis)
Many of us never will.
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis, worries about the declining population and fears it may go the way of Franklin's bumble bee, which he hasn't seen since 2006.
That's why he and his colleagues were so excited to find a male Bombus occidentalis on Mt. Shasta, above 5,000 feet, on Aug. 15. It was foraging on buckwheat (Eriogonum sp.).
Thorp was there with several local U.S. Forest Service employees: wildlife biologist Debbie Derby, who actually netted the bee; and biological technicians Susan Thomas, Kendra Bainbridge and Lauran Yerkes.
"Just as we were celebrating the find, we were joined by two other USFS personnel: Carolyn Napper, district ranger, and Johnny Dame, Panther Campground host," Thorp recalled. "So there were lots of witnesses to the rare find."
A rare find, indeed.
The Western bumble bee, a close relative of Franklin's bumble bee (Bombus franklini), "disappeared from the western part of its range at the same time as Franklin's bumble bee declined," said Thorp, who keeps an eye out for both species on his trips to southern Oregon and northern California.
The habitat of the Franklin's bumble bee, which many fear is extinct, is a 13,300-square-mile area of Siskiyou and Trinity counties in California, and Jackson, Douglas and Josephine counties in Oregon.
"The Western bumble bee occurred throughout the range of Franklin’s, but apparently declined from central California to southern British Columbia west of the Sierra Cascade Range at the same time as the decline of Franklin's bumble bee, " Thorp said.
However, the Western bumble bee "seems to have persisted through most of the rest of its range from Alaska through areas east of the Sierra-Cascade to the Rocky Mountains and south to Arizona and New Mexico," Thorp pointed out. "We have no good idea what the population trends have been within this large area, since no one has been closely monitoring its populations there."
We're glad to see the increased interest in bumble bees. And especially glad to see that this week the Xerces Society for Invertebrate Conservation announced the publication of Bumble Bees of the Western United States, co-authored by Jonathan Koch, James Strange and Paul Williams. You can order it online.
Bombus occidentalis and Bombus franklini are among the Bombus species represented.
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis, is on a mission.
He and fellow members of the Xerces Society for Invertebrate Conservation are trying to save Franklin's bumble bee from extinction.
So the news that came out today about this critically imperiled bumble bee was both good and bad.
It's good that the U.S. Fish and Wildlife Service (USFWS) today announced that the petition submitted by Thorp and the Xerces Society in June 2010 to list Franklin’s bumble bee under the National Endangered Species Act has moved to the next step in the process, the 12-month review period. This may lead to an “endangered species” listing and provide protective status.
That's good. But it's bad in that Franklin's bumble bee hasn't been seen since 2006.
It's possible that it may already be extinct but Thorp holds out hope. He's been monitoring the declining population since 1998.
Franklin’s bumble bee, Bombus franklini (Frison), occupies only a narrow range of southern Oregon and northern California. Its range, a 13,300-square-mile area confined to Siskiyou and Trinity counties in California; and Jackson, Douglas and Josephine counties in Oregon, is thought to be the smallest of any other bumble bee in North America and the world.
Thorp, who maintains an office at the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis, sighted 94 of the species in 1998, but only 20 in 1999. The numbers soon began declining drastically (except for 2002):
2000: Nine sightings
2007 through 2011: None.
This year Thorp surveyed the bumble bee's historical sites on five separate trips encompassing several days each: two in June and one each in July, August and September.
Zip. Zilch. Nada.
Franklin's bumble bee, mostly black, has distinctive yellow markings on the front of its thorax and top of its head. It has a solid black abdomen "with just a touch of white at the tip, and an inverted U-shaped design between its wing bases," Thorp said.
Take a close look at his photo of Franklin's bumble bee on a California poppy, the state flower. Let's hope it's not one of the last photos of this unique bumble bee.
Robbin Thorp thinks he'll find it again.
“My experience with the Western bumble bee (B. occidentalis) indicates that populations can remain ‘under the radar’ for long periods of time when their numbers are low,” he said.
Read more about this bumble bee and Thorp's mission on the UC Davis Department of Entomology website.
If you want to see pinned specimens, visit the Bohart Museum of Entomology, 1124 Academic Surge on California Drive, UC Davis campus.
That's because it's rarely seen.
Its narrow distribution range covers parts of southern Oregon (Jackson, Douglas and Josephine counties) and northern California (Siskiyou and Trinity counties). That's 190 miles north-south and 70 miles east-west.
"Franklin’s bumble bee has the smallest range of distribution of any of our 60 species of North American bumble bees, and perhaps of the 250 bumble bees in the world,” said noted bumble bee expert and native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis.
Thorp, who has been closely monitoring the Bombus franklini population since 1998, counted 100 that first year. In 2003, he found only three. And since 2006, only one.
Franklin's bumble bee may already be extinct, but he hopes not. Thorp and The Xerces Society for Invertebrate Conservation, headquartered in Portland, Ore., petitioned the U.S. Fish and Wildlife Service on June 23 to place it on the endangered species list.
A decision may be reached within 90 days.
“The decline of Franklin’s bumble bee is a signal that something is wrong in its environment,” said Thorp. “This is the canary-in-the-coal-mine measure.”
He hypothesizes that the key reason for its disappearance may be an exotic disease that spread from commercial bumble bee colonies to wild bumble bee populations.
“People often ask the value of Franklin’s bumble bee," said Thorp, a member of the California Academy of Sciences and The Xerces Society. "In terms of a direct contribution to the grand scale of human economies, perhaps not much, but no one has measured its contribution in those terms. However, in the grand scheme of our planet and its environmental values, I would say it is priceless.”“Loss of a species, especially a pollinator, diminishes our global environment. Bumble bees provide an important ecological service--pollination. This service is critical to reproduction of a huge diversity of plants that in turn provide shelter, food (seeds, fruits) to diverse wildlife. The potential cascade of effects from the removal of even one localized pollinator may affect us directly and indirectly.”
Is it too late to provide protection for a species that may already be extinct?
No, it's not.
“Other species, especially plants and insects, thought to be extinct have reappeared after years of not being seen,” the UC Davis scientist said. “When populations of species are in decline, they may reach such low levels that they are not detected for several years in a row, despite intensive surveys--flying under the radar so to speak. It is my hope that this is the case with Franklin’s bumble bee.”“One positive sign,” Thorp said, “comes from increasing finds the past two years of a related species, the Western bumble bee, which exhibited similar declines at the same time and places."
On his most recent trip, July 21-24, to the narrow distribution range, he didn't find Franklin's bumble bee but he did find the related Western bumble bee at two sites, one individual at each site.
That's a good sign. Perhaps B. franklini will eventually show up as well. Thorp is planning another trip in mid-August and another in early September.
Meanwhile, if the critically imperiled Franklin's bumble is granted protective status, a snowball effect could occur.
This could “stimulate research into the probable causes of its decline,” Thorp said. “This may not only lead to its recovery, but also help us better understand environmental threats to pollinators and how to prevent them in future. This petition also serves as a wake-up call to the importance of pollinators and the need to provide protections from the various threats to the health of their populations.”
More about the mission to Save Franklin's bumble bee
Watch Robbin Thorp's webcast about Franklin's bumble bee
Let's have a show of hands.
How many of you have seen Franklin's bumble bee in the wild?
Never HEARD of it, you say?
Well, you probably will never SEE it, either. Bumble bee experts think it may be extinct.
Franklin's bumble bee is native to southern Oregon and northern California, but in recent years, it's been a "no show."
"Franklin's bumble bee has the most restricted distribution range of any bumble bee in North America, and possibly the world," said UC Davis researcher Robbin Thorp, a noted authority on bumble bees. Its range is about 190 miles north to south and 70 miles east to west in a narrow stretch between southern Oregon and northern California, between the coast and the Sierra-Cascade ranges.
Its known distribution: Jackson, Douglas and Josephine counties in Oregon, and Siskiyou and Trinity counties in California. It lives at elevations ranging from 540 feet in the north to 6800 feet in the south.
Thorp launched his scientific surveys for Franklin's bumble bee in 1998. He documented about 100 of them that year. They were, he said, fairly common.
Since 2004, however, he's seen the unique bumble bee only once. And that was a solitary worker in August 2006 at Mt. Ashland, Ore.
The black-faced bumble bee (Bombus franklini) is distinguished by a black inverted U-shape on its yellow thorax. See Thorp's photo below. Note also the yellow markings atop its head.
Franklin's bumble bee frequents (or shall we say, "used to" frequent) California poppies, lupines, vetch, wild roses, blackberries, clover, sweet peas, horsemint and mountain penny royal during its flight season, from mid-May through September. It collects (or shall we say "used to" collect) pollen primarily from lupines and poppes and gathers nectar mainly from mints.
Thorp just returned from the region in mid-May and found nothing. He journeys to the region three to five times a year, spending several days looking for the bumble bee on each trip.
It's not there.
Thorp is concerned, as we all should be, that humankind is disturbing, destroying and altering the habitat where the native pollinators exist.
He'll be speaking on the plight of the bumble bee from 12:10 to 1 p.m., Wednesday, May 27 at 122 Briggs Hall, UC Davis. His talk will be Webcast. You can view it by signing in here at that time. Later, it will be archived on this page.
Bumble bees, Thorp said, are important to our ecosystem. Wildlife, including birds, elk, deer and bears, depend on pollination of fruits, nuts and berries for their survival.
Other species of bumble bees are commercially reared to pollinate greenhouse tomatoes, peppers and strawberries. They pollinate about 15 percent of our food crops, valued at $3 billion, Thorp estimated.
Goodbye, Franklin's Bumble Bee? Hello, distinction?