Protecting these species is not only the right thing to do; it will also help to maintain the healthy ecosystems that make California such a remarkable and productive state.
Aiming to secure protections for imperiled pollinators, the Xerces Society, working with Defenders of Wildlife and the Center for Food Safety, has submitted a petition for the listing of four species of native bumble bees under the California Endangered Species Act. An endangered listing would protect these species from activities that could cause them to go extinct, and would allow for additional conservation measures.
The western bumble bee (Bombus occidentalis occidentalis), Franklin’s bumble bee (Bombus franklini), Crotch’s bumble bee (Bombus crotchii), and the Suckley cuckoo bumble bee (Bombus suckleyi) all are at risk of extinction. The International Union for Conservation of Nature (IUCN) Bumblebee Specialist Group, a global network of bumble bee researchers dedicated to the conservation of bumble bees, evaluated each of these species on the IUCN Red List of Threatened Species and found them to be:
- Critically Endangered (Suckley cuckoo bumble bee and Franklin’s bumble bee).
- Endangered (Crotch’s bumble bee).
- Vulnerable (western bumble bee).
It is important to note that this petition concerns a specific subspecies of the western bumble bee, Bombus occidentalis occidentalis, which has not yet been formally listed by the IUCN. However, recent analysis of changes in range and relative abundance of B. occidentalis occidentalis by Rich Hatfield, the Xerces Society’s senior endangered species conservation biologist, suggests that this subspecies would meet the criteria of Endangered on the IUCN Red List.
These four species are primarily threatened by habitat loss, diseases, and pesticides. Although their combined historic ranges span most of the state of California, they currently exist in only a few areas. In the case of the western bumble bee subspecies B. occidentalis occidentalis, these losses have been rapid and recent. Until the late 1990s, the western bumble bee was one of the most common bumble bees within its range. In the twenty years since then, its relative abundance has declined by 84 percent. The Suckley cuckoo bumble bee relies upon the western bumble bee to complete its life cycle, and so as the western bumble bee has declined, so has this species. The Suckley cuckoo bumble bee has seen an 80 percent decline in relative abundance.
Crotch’s bumble bee persists in only 20 percent of its historic range, and has declined by 98 percent in relative abundance. This bee historically occurred from the northern Central Valley to Baja California, Mexico, but now is found primarily in southern coastal habitats and areas near Sacramento.
Most alarmingly, Franklin’s bumble bee is in imminent danger of extinction, and has not been seen in the wild since 2006. It has the unfortunate distinction of having the most limited geographic distribution of any bumble bee in North America and possibly the world. Historically, Franklin’s bumble bee occurred in an area that is only about 60 miles wide, located in the Siskiyou mountains of northern California and southern Oregon.
Protecting these species is not only the right thing to do; it will also help to maintain the healthy ecosystems that make California such a remarkable and productive state. After all, California accounts for more than 13 percent of the nation’s total agricultural output, and native bees – including bumble bees – play a key role in supporting the production of many of California’s specialty crops like tomatoes, peppers, melon, squash, cotton, and almonds. Native ecosystems, from the flower fields of the Carrizo plain to the montane meadows of the Sierra Nevada, also rely upon these charismatic pollinators. Conserving a diversity of native pollinators within the state is paramount to maintaining the state’s natural heritage, a value consistent with California’s new Biodiversity Initiative, which calls for fallowed agricultural land to be transformed into habitat for bees, creating a “pollinator highway” across the state.
“Native pollinators, including bumble bees, provide ecosystem services estimated at more than nine billion dollars annually in the U.S.,” said Sarina Jepsen, director of the Xerces Society’s endangered species program and petition coauthor. “By acting on this petition, California has an opportunity to demonstrate how an individual state can lead the nation in protecting a diverse suite of pollinators, benefiting both agriculture and natural areas.”
Indeed, a listing under California’s Endangered Species Act would not only protect these four bumble bee species from extinction, but also preserve their vital contributions to agriculture and ecosystems. An increased investment in pollinator habitat, along with protection from insecticides and pathogens, will be instrumental in preventing the extinction of these important bumble bee species. We hope that the state of California will support the listing of these four bumble bee species—and with it, the state’s economic and environmental future.