Professor Thorp (1933-2019), a 30-year member of the Department of Entomology and Nematology and a worldwide authority on bees, was a tireless advocate of bumble bee conservation. During his retirement, he co-authored Bumble Bees of North America: An Identification Guide (Princeton University, 2014) and California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday, 2014).
And every summer from 2002 to 2018, Thorp volunteered his time and expertise to teach at The Bee Course, an annual workshop sponsored by the American Museum of Natural History and held at the Southwestern Research Station, Portal, Ariz.
Thorp also served as the regional co-chair of the Wild Bee Specialist Group of the International Union for Conservation of Nature (IUCN) and sounded the alarm about bumble bee declines, including Franklin's bumble bee, Bombus franklini, found only in its narrow distribution range of southern Oregon and northern California. Thorp last saw it near Mt. Ashland in 2006 and it is is now feared extinct or at the brink of extinction. The bee inhabits--or did--a 13,300-square-mile area confined to five counties--Siskiyou and Trinity counties in California; and Jackson, Douglas and Josephine counties in Oregon.
Enter the California Bumble Bee Atlas (CBBA), a collaboration of the California Department of Fish and Wildlife (CDFW), Sacramento, and the Xerces Society for Invertebrate Conservation, headquartered in Portland, Ore. Launched in March 2022, the Atlas is a "collaborative community science effort to track and conserve the state's native bumble bee species," according to Dylan Winkler, bumble bee scientific aide for the CDFW's Wildlife Diversity Program.
Back in September 2021, the U.S. Fish and Wildlife Service announced that the American bumble bee, "whose populations have plummeted by nearly 90 percent, may warrant Endangered Species Act protection." The announcement kicked off a one-year status assessment of the species. (See news story)
If you're interested in bumble bee conservation, take note. Winkler will lead a "Bumble Bee Walk" from 10 a.m. to noon on Saturday, May 28 in the UC Davis Arboretum and Public Garden. The goal is to teach interested participants how to survey bumble bees. You can pre-register at https://arcg.is/0PDyO4. Organizers plan to cap attendance at 20 people. Details about this Atlas event and several more scheduled in June:
- Saturday, May 28: UC Davis Arboretum, Davis, CA (Yolo County), parking at Putah Creek Lodge Parking Lot, Garrod Drive, Davis, CA 95616. Tour of the native plant gardens and the forest along Putah Creek from 10 a.m. to noon.
- Saturday, June 4: The Gardens at Lake Merritt, 666 Bellevue Avenue, Oakland, CA (Alameda County). Tour of the gardens from 9 a.m. to 11 a.m.
- Sunday, June 5: College of Marin at Kentfield (Marin County), parking at covered Lots 6/7 off College Ave, Kentfield, CA 94904. Details: Meet at bridge over Corte Madera Creek. Tour of the campus native plants from 10 a.m. to noon.
- Saturday, June 18: Soil Born Farms, Rancho Cordova, CA (Sacramento County), parking at Soil Born Farms: American River Ranch, 2140 Chase Drive, Rancho Cordova, CA 95670. As part of National Pollinator Week, the group will tour the gardens from 10 a.m. to noon. Closed-toed shoes required.
Of the 50 species of bumble bees found in North America, an estimated 25 inhabit California. Overall, a quarter is at risk, according to the Atlas website. The decline is attributed to "loss or fragmentation of habitat, pesticide exposure, climate change, overgrazing, competition with honey bees, low genetic diversity, and perhaps most significant of all, the introduction and distribution of pathogens through commercial honey bee and bumble bee colonies used for crop pollination. All of these factors likely interact, increasing pollinator vulnerability. To support bumble bees, it is critical to protect existing habitat while creating and maintaining new habitat."
Winkler says "we will be using butterfly nets to catch bees, then move them to small vials, and chill them in coolers with ice, so we can take ID'able photographs of them before releasing." The full protocol is at https://www.cabumblebeeatlas.org/point-surveys.html
What bumble bees might you see May 28 in the Arboretum? Bombus vosnesenskii, the yellow-faced bumble bee, and B. melanopygus, the black-tailed bumble bee. "There is a record of B. crotchii at the arboretum from last year around the same date, which is rare and would be amazing to see!" Winkler said.
The project is funded by the U.S. Fish and Wildlife Service through the Wildlife and Sport Fish Restoration Fund. Funding is also provided by the Bureau of Land Management and several private foundations. Read more about the project and the list of coordinators here.
Picture this during National Pollinator Week: five monarch caterpillars and assorted honey bees sharing tropical milkweed.
It was love at first bite. Or love at first sip.
The 'cats kept munching and the bees kept foraging. Neither species seemed interested in the other.
But the adult monarchs definitely showed more interest in the tropical milkweed (Asclepias curassavica), a non-native, than the other two species, both natives, that we planted: the narrow leaf (A. fascicularis) and showy milkweed (A. speciosa).
They laid eggs only on the tropical milkweed, and so far, have produced five caterpillars.
The score to date:
Tropical milkweed: 5 caterpillars
Narrow leaf milkweed: 0
Showy milkweed: 0
Reminder: Folks planting the tropical milkweed in temperate zones (like here in Vacaville,Calif.) must remove or cut back the tropical milkweed by winter. "A protozoan parasite of monarch butterflies, Ophryocystis elektroscirrha or OE for short, can travel with monarchs visiting the plants and become deposited on leaves," explains the Xerces Society for Invertebrate Conservation.
Yes, indeed. But meanwhile, we're witnessing untold sharing on the wildly popular tropical milkweed by not only monarch caterpillars but honey bees, syrphid flies, bumble bees, carpenter bees, leafcutter bees and sweat bees.
We gardeners and photographers are also drawn to the spectacular red, orange and yellow flowers that add both beauty and color to a cherished pollinator patch in the midst of the COVID-19 pandemic...and National Pollinator Week.
If you've ever wanted to converse with butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology, about "butterflies and the apocalypse" and sip a beer (or another beverage) at the bar at the same time, here's your chance.
The Davis Science Café has booked "A Conversation with Arthur Shapiro: Butterflies as Heralds of the Apocalypse" at 5:30 p.m., Wednesday, April 10 in the G Street Wunderbar, located at 228 G St., Davis. The event, hosted by professor Jared Shaw, professor and interim department chair of the UC Davis Department of Chemistry, is free and open to the public (but the refreshments are not).
Shapiro has monitored butterfly population trends on a transect across central California since 1972. The 10 sites stretch from the Sacramento River Delta through the Sacramento Valley and Sierra Nevada mountains to the high desert of the Western Great Basin. The largest and oldest database in North America, it was recently cited by British conservation biologist Chris Thomas in a worldwide study of insect biomass.
What's going on with the butterflies?
The overwintering western population of the monarch butterfly on the central California coast declined 86 percent last winter, the Xerces Society for Invertebrate Conservation indicates on its website. "Working at a conservation nonprofit means that we often come across bad news, but the results from this winter's Western Monarch Thanksgiving Count left us shocked: an all-time record low of 28,429 monarchs at 213 sites. This number is an 86% drop from the previous count done at Thanksgiving 2017, when 192,668 monarchs were counted at 263 sites (comparing only the sites monitored in both years)—and a dizzying 99.4% decline from the numbers present in the 1980s (Schultz et al. 2017). In short, only one of every 160 monarchs present in the 1980s exists today."
At the 2018 Butterfly Summit at Annie's Annuals and Perennials in Richmond, Shapiro told the crowd that "The vast majority of the butterflies we monitor are emerging earlier in the year now than they were in the 1970s."
His research shows that not only are butterflies coming out earlier, but "we also find trends in population and species richness."
Shapiro, a member of the UC Davis faculty since 1971 and author of the book, Field Guide to Butterflies of the San Francisco Bay Area and Sacramento Valley Regions, said that "in a nutshell, at low elevations, butterfly faunas have been declining slowly until 1999. In 1999, 17 species had an abrupt fall in abundance, spontaneously. On its face, this was a non-random event. The decline was then rapid from 1999 to the onset of the recent drought and then things went up again."
Science Café, initially supported by the National Science Foundation, is currently supported by the Department of Chemistry and Division of Mathematical and Physical Sciences and promoted by Capital Science Communicators.
Science Café sessions are hosted the second Wednesday of each month. Topics so far this year? Plant ecologist Mark Schwartz of the UC Davis Department Environmental Sciences and Policy held forth at the March session on "Does California Have a Wildfire Problem? Can It Be Fixed?" The February session featured Professor Roland Faller of the UC Davis Department of Chemical Engineering on "Using Computers to Understand Materials: From Proteins to Semiconductors" while Professor Denis Marcellin-Little of the UC Davis School of Veterinary Medicine's Surgical and Radiological Sciences discussed "Don't Try That at Home; High-End 3D Printing in Orthopedic Surgery" at the January session.
So it's butterflies and the apocalypse on April 10. Ask your questions, sip an adult beverage (or another beverage) and enjoy the evening!/span>
You're in luck.
The Xerces Society for Invertebrate Conservation is planning a free field trip on "Cover Cropping for Beneficial Insects" from 9 to 11:30 a.m., Wednesday, March 28 at the Muller Ranch LLC, located at 15810 County Road 95, Woodland. The event is open to the public, but reservations should be made: email Jessa Kay Cruz, Xerces Society's senior pollinator and ag biodiversity specialist at firstname.lastname@example.org.
Among those speaking is Yolo County Farm Advisor Rachael Long, an expert on hedgerows and cover crops. See her UC Agriculture and Natural Resources (UC ANR) publication on "Establishing Hedgerows on Farms in California."
Here's the agenda for the field trip:
- 8:30 to 9 a.m.: Arrive and Sign-In
- 9 to 9:20 a.m.: Welcome and Introduction, Project Background
Jessa Kay Cruz, Senior Pollinator and Ag Biodiversity Specialist, The Xerces Society
- 9:20 to 9:40 a.m. Cover Cropping for Soil Health
Jeff Borum, Soil Health Coordinator
- 9:40 to 10 a.m. Cover Cropping for Beneficial Insects
Rachael Long, Farm Advisor, UC Cooperative Extension
- 10 to 10:30 a.m.: Insect Ecology, Plant Species Selection, Implementation and Management
Jessa Kay Cruz, Senior Pollinator and Ag Biodiversity Specialist, The Xerces Society
- 10:30 to 10:50 a.m.: A Farmer's Perspective: Why Do It and How Well Does it Work?
Colin Thomas Muller, Muller Ranch LLC
- 10:50 to 11:10 a.m.: Accessing Natural Resources Conservation Service (NRCS) Cost-Share Programs and Understanding the Planning Process
Fanny Ye, Soil Conservationist, NRCS, and Corey Shake, Point Blue / NRCS Partner Biologist
Continuing education credits are available.
On the field trip, you're likely to learn about pollinators, predators, pests and parasitoids as well as plants (cover crops). Keep your eyes out for such beneficial insects as lady beetles, aka ladybugs. These predators make short work of aphids, scales and other soft-bodied insects. Keep them close!
A Sept. 7 article in Reuters, headlined "Monarchs in Western United States Risk Extinction, Scientists Say," indicated that "Monarch butterflies west of the Rocky Mountains are teetering on the edge of extinction, with the number wintering in California down more than 90 percent from the 1980s, researchers said in a study published on Thursday."
Reuters' reporter Laura Zuckerman wrote that "The migratory monarchs of the western United States have a 63 percent chance of extinction in 20 years and an 84 percent chance in 50 years if current trends continue, according to the study."
The scientists, led by Washington State University conservation biologist Cheryl Schultz, published their work in the journal Biological Conservation. It was funded by the U.S. Fish and Wildlife Service, which is weighing the prospect of offering federal protection for monarch butterflies through the Endangered Species Act. The Xerces Society for Invertebrate Conservation is among those spearheading the effort.
Noted lepidopterist Arthur Shapiro, UC Davis distinguished professor of evolution and ecology who has studied butterflies, including the monarchs, for more than four decades, doubts that the western monarchs are teetering on the edge of extinction.
Shapiro, who maintains a website, Art's Butterfly World. says that yes, the western monarchs have been declining faster than the eastern monarchs, as per the Biological Conservation paper. However, during the drought, California populations appeared to rebound significantly, and it is not known whether the trend will persist, he says.
Their comprehensive and well-researched work, titled "Understanding a Migratory Species in a Changing World: Climatic Effects and Demographic Declines in the Western Monarch Revealed by Four Decades of Intensive Monitoring," was funded in part by the National Science Foundation. Their Oecologia abstract: "Migratory animals pose unique challenges for conservation biologists, and we have much to learn about how migratory species respond to drivers of global change. Research has cast doubt on the stability of the eastern monarch butterfly (Danaus plexippus) population in North America, but the western monarchs have not been as intensively examined. Using a Bayesia hierarchial model, sightings of western monarchs over approximately 40 years were investigated using summer flight records from ten sites along an elevational transect in Northern California."
"Multiple weather variable were examined, including local and regional temperature and precipitation. Population trends from the ten focal sites and a subset of western overwintering sites were compared to summer and overwintering data from the eastern migration. Records showed western overwintering grounds and western breeding grounds had negative trends over time, with declines concentrated early in the breeding season, which were potentially more severe than in the eastern population."
"Temporal variation in the western monarch also appears to be largely independent of (uncorrelated with) the dynamics in the east. For our focal sits, warmer temperatures had positive effect during spring. These climatic associations add to our understanding of biotic-abiotic interactions in a migratory butterfly, but shifting climatic conditions do not explain the overall, long-term, negative population trajectory observed in our data."
In acknowledgments, Shapiro and his colleagues thanked the Xerces Society for Invertebrate Conservation and the North American Butterfly Association for the monarch counts and making the data publicly available.
Meanwhile, since late August, the western monarchs (Arizona, California, Nevada, Oregon, Washington, Idaho and Utah) have been winging their way to their overwintering spots to forested groves along coastal California.
And then, around February, they will head inland to start the process again.
It's an amazing phenomenon.
As I write this, four monarchs are gathering some flight fuel, nectaring from two M's: milkweed and Mexican sunflower in our little pollinator garden in Vacaville, Calif., part of their migratory path to the coast. They flutter from flower to flower, seemingly unaware of the California scrub jay circling them and a photographer zeroing in on them. Or the rain about to fall.