What is in this article?:
- Surveys for Franklin's bumble bee, conducted since 1998, clearly show declining population. Sightings decreased from 94 in 1998 to 20 in 1999 to 9 in 2000 to one in 2001. Sightings increased slightly to 20 in 2002, but dropped to three in 2003. Thorp saw none in 2004 and 2005; one in 2006; and none since.
It's good news for the critically imperiled Franklin's bumble bee, which Robbin Thorp of the University of California, Davis, has been tracking since 1998.
A petition spearheaded by Thorp and the Xerces Society for Invertebrate Conservation 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 the U.S. Fish and Wildlife Service (USFWS) listing it as "endangered" and providing protective status.
The bad news: Thorp hasn't seen Franklin's bumble bee since 2006.
"I am still hopeful that Franklin's bumble bee is still out there somewhere," said Thorp, emeritus professor of entomology. "Over the last 13 years I have watched the populations of this bumble bee decline precipitously. My hope is this species can recover before it is too late."
Thorp researches the declining population of Franklin's bumble bee, Bombus franklini (Frison), found only in 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's surveys, conducted since 1998, clearly show the declining population. Sightings decreased from 94 in 1998 to 20 in 1999 to 9 in 2000 to one in 2001. Sightings increased slightly to 20 in 2002, but dropped to three in 2003. Thorp saw none in 2004 and 2005; one in 2006; and none since.
"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. Thorp did not see the Western bumble bee between 2002-08, but now, although sightings are rare, they are "consistently encountered."
This year Thorp surveyed the bumble bee's historical sites in southern Oregon and northern California on five separate trips of several days each: two in June and one each in July, August and September. "Flowering and bumble bee phenology were pushed back about a month this year due to our cold wet spring," he said.
"I managed to see and photograph workers of B. occidentalis at two sites on my August trip. I had hoped to see males and even a Franklin's on my last visit in September but, alas, no luck.
"However, flowering was more like mid-August and lots of other species of worker bumble bees were still foraging," he noted. "Males and new queens were also on the wing. The new queens will mate and hibernate to emerge and produce new colonies next year. The old queens and the rest of this year's colony members will die out soon, as this season winds to a close."