The California Bumble Bee Atlas 2026 is a statewide volunteer effort to map California's 25 native bumble bee species. The Atlas, modeled on the Pacific Northwest Bumble Bee Atlas run by the Xerces Society, divides California into a grid of survey cells and asks trained volunteers to walk standardized transects, photograph every Bombus they find, and submit data that can inform conservation decisions.
This guide walks Sacramento residents through how the Atlas works, what a survey involves, and how to sign up.
Key takeaway: The California Bumble Bee Atlas relies on trained volunteers, and Sacramento residents can take part. Register through the Xerces Society, or reach out to us about volunteering.
TL;DR: California Bumble Bee Atlas 2026 in 5 Bullets
- Statewide volunteer survey of all 25 California bumble bee species, modeled on the Pacific Northwest Bumble Bee Atlas (2018-2023) run by Xerces Society, USDA Forest Service, and Idaho Fish & Game.
- Training starts with an online course hosted by the Xerces Society.
- Each survey takes 45 to 90 minutes, twice per assigned cell per season (May-September).
- Data flows into the Xerces Society Bombus database, the California Department of Fish and Wildlife conservation system, and (for confirmed sightings) Bumble Bee Watch.
- No experience required.
What the California Bumble Bee Atlas Actually Is
A "bumble bee atlas" is a structured statewide survey that combines volunteers, professional coordination, and a standardized protocol so the resulting data can be used in conservation decisions — not a pile of casual photos. The model was proven by the Pacific Northwest Bumble Bee Atlas (2018-2023), coordinated by the Xerces Society with USDA Forest Service and Idaho, Washington, and Oregon agencies. It trained more than 600 volunteers, surveyed every 50-kilometer grid cell in the three-state region, and produced range maps cited in federal Endangered Species Act listings.
California is now running the same playbook, scaled to the largest Bombus fauna in the western United States — about 25 species. At least four are in documented decline. Two (the western bumble bee, Bombus occidentalis, and Crotch's bumble bee, Bombus crotchii) are formal candidates for California Endangered Species Act listing.
The Atlas is coordinated by the Xerces Society with California Department of Fish and Wildlife. Volunteers register through the Xerces portal, complete training, and are assigned a grid cell to survey twice during the May-September flight season.
Bumble Bees to Learn Before You Survey
These six species are worth learning to recognize before you survey.
- Crotch's bumble bee (Bombus crotchii) — Black face and head, yellow on the front thorax and second abdominal segment. CESA candidate. Any 2026 Sacramento sighting is meaningful.
- Western bumble bee (Bombus occidentalis) — Black-and-yellow with a white tail tip. Once common, now extremely rare in the Central Valley. CESA candidate.
- Morrison's bumble bee (Bombus morrisoni) — Yellow head, yellow thorax, all-yellow abdomen. Historically widespread, now patchy. Foothill grasslands east of Sacramento.
- Yellow-faced bumble bee (Bombus vosnesenskii) — Bright yellow face, narrow yellow bands. Still common; trend data needed. See our yellow-faced bumble bee guide.
- California bumble bee (Bombus californicus) — Black with yellow on the rear thorax and fourth abdominal segment. Under-recorded.
- Black-tailed bumble bee (Bombus melanopygus) — Sacramento form usually has a red-orange abdominal band. Earliest-emerging Bombus in the region.
The Atlas only catalogues Bombus, but our broader citizen-science guide on documenting Sacramento bees through iNaturalist and Bumble Bee Watch covers what to do with the honey bees, carpenter bees, and smaller natives you photograph along the way.
How a Survey Actually Works
A standardized Atlas survey is deliberately simple — the design philosophy is "anyone with two hours and a phone can collect research-grade data." Each volunteer is assigned a 50-kilometer grid cell with one or more survey patches.
- Pick a survey patch (meadow, garden, hedgerow, or wetland edge in current bloom) inside your assigned grid cell.
- Walk a 45-to-90-minute transect on a warm sunny morning between 9 a.m. and 4 p.m. Record start/end time, weather, and dominant blooms.
- Photograph every bumble bee — three angles minimum: top, side, face. Net-and-release into a clear vial is allowed and produces dramatically more reliable IDs than free-flight shots.
- Record each observation in the Atlas mobile form (or paper backup): GPS, time, host plant, photo numbers, best species guess.
- Submit at the end of the day. Photos auto-upload to the Xerces database; trained reviewers confirm species in 1-3 weeks.
Each cell is surveyed twice — early season (May-June, queen activity) and late season (July-September, worker abundance).
Training
Online course
The Xerces Society hosts the official Atlas training online. It covers Bombus biology, target species, the survey protocol, photography technique, and the data form. One evening, or two short sittings. Completion is required before you receive a grid cell assignment.
First survey
You receive your grid cell and schedule a survey window.
Pro tip: practice the "net into vial, photograph through vial, release" sequence on honey bees in your yard before your first real survey. The mechanical motion is the part that takes reps. By the time a Crotch's lands on your buckwheat, you want the vial reflex to be automatic.
What Your Survey Data Actually Produces
- Range maps. Every confirmed observation is plotted on the public Atlas map and the Xerces Bombus database, used to plan habitat protection and identify population strongholds.
- Conservation decisions. Atlas data can inform how California evaluates species such as Crotch's, western, and Morrison's bumble bees.
- Restoration targeting. Recent occurrence data helps show where habitat work could matter most.
Common Beginner Questions
Will I get stung?
Almost certainly not. Bumble bees are remarkably docile when foraging and tolerate a phone or vial at close range as long as you move slowly. A vialed bumble bee released within 30 to 60 seconds is unstressed.
I have kids — can they help?
Yes. Kids can come along and use the iNaturalist Seek app while the adult runs the formal survey. Our bee education for kids in Sacramento guide covers age-appropriate ways to involve children in pollinator science.
What if I cannot commit to a full grid cell?
If a full cell is too much, reach out to us about volunteering. Our broader volunteer bee conservation guide covers other ways to get involved.
When is the survey season?
Atlas surveys run during the May through September flight season. Check the California Bumble Bee Atlas portal for current dates and training.
How to Sign Up
- Through The Bee Conservatory. Reach out through our volunteer page to ask about volunteering.
- Through the Xerces Society. Register at the California Bumble Bee Atlas portal and request a Sacramento County cell.
A Saturday That Counts
The California Bumble Bee Atlas is a volunteer opportunity where a few mornings of survey add to the data used to track which bumble bees need protection. The bumble bees, for what it is worth, are already out there: black-and-yellow blurs on California buckwheat, waiting for someone with a phone and three free hours to notice them.
Ready to join the California Bumble Bee Atlas? Register through the Xerces Society portal, or reach out to us about volunteering.