Citizen scientists count bumble bees to save them


Leif Richardson, a California Bumble Bee Atlas organizer, shows volunteers a partially anesthetized, rare Crotch’s Bumble Bee, caught during a recent training for the survey at the Los Angeles County Arboretum. Photo by Susan Valot.

If you see someone with a net staring into a flowering bush this summer, there’s a good chance they’re counting bumble bees. About 500 volunteers are spending time in parks, reserves and backyards looking for bumble bees.

It’s part of the California Bumble Bee Atlas, a survey to figure out what kind of bumble bees are congregating where. Native bees, including bumble bees, not only pollinate flowers, but also most crops in California, keeping a major engine of the state’s economy buzzing.

And this year, it seems a bit harder to find bumble bees than usual. 

“We know that there is a problem for bumble bees, that bumble bees are becoming rarer, that many species are in trouble,” says Leif Richardson with the Xerces Society, the conservation nonprofit that created the California Bumble Bee Atlas project, which started in 2022. “In North America, about a quarter of all species of bumble bees are at some risk of extinction. That’s a lot of animals.”

Richardson, who helps oversee the California project, says if the California Department of Fish and Wildlife or the federal government decides to list the bees as endangered later, the data they collect for the Atlas could be the reason why, helping officials evaluate whether critical habitat is needed and if so, where.

Roughly 25 bumble bee species call California home. Last year, the California Department of Fish and Wildlife put four bumble bee species on the candidate list to consider whether they need protection as endangered or threatened. 

Leif Richardson of the California Bumble Bee Atlas shows a group of volunteers the difference between a bumble bee, a carpenter bee and a honey bee. Photo by Susan Valot.

Richardson spent a recent Saturday at the Los Angeles Arboretum in Arcadia teaching about a dozen new volunteers what to look for and how to use an insect net to safely catch a bumble bee.  

Soon volunteer Diana Nightingale of the San Gabriel Valley discovers something in her net. She nervously tries to coax it into a vial, but the insect finds a hole and flies away in a matter of seconds. It’s trickier than it sounds. Still, Nightingale is excited to be here.

“Every time I see a bumble bee, I just fall in love … madly in love,” Nightingale says. “I used to run a California butterfly pavilion, and I kind of fell in love with insects.”

Volunteers catch the elusive bees, cool them to anesthetize them, and then photograph and document them, along with the flower they were caught on. That’s all then fed into an online database. The bees are released, unharmed.

“It’s an amazing resource, the fact that people donate this labor to us, to the project,” Richardson says. “We are able to gather thousands of records of bumble bees each summer.”

Richardson says climate change seems to be forcing bees to pull out of the hotter parts of their range and head upslope. Some higher elevation bees could simply run out of places to go. 

“We know the bumble bee distributions are changing, and we know that habitats are changing. We know that habitat conversion to development, for example, is a leading threat for bees. And we want to characterize all of that,” Richardson says. “We want to characterize where the bees occur now, where they don’t occur now, what the habitat quality is like and try to connect those things.”

The warming climate also complicates the relationship between bees and the plants they pollinate. Shifts in temperature could lead to plants flowering early, before the bumble bees emerge from hibernation. The plants could lose a pollinator and the bumble bees could lose food. And with this year’s cold and rains, the wildflowers have bloomed later, with the bees delayed, too.

Richardson speculates that the heavy snowpack in the mountains has led the bees to stay in hibernation longer.

“They could run out of stored resources, internal resources, and starve. So there is a concern there. They could be damaged by the flood waters or just all of this water. We don’t really know,” Richardson says. “But if they survive the winter, this is a very good spring to be a bumble bee. There are more flowers than ever.”

The native blooms in the Crescent Farm section of the Los Angeles County Arboretum are prime habitat for bumble bees. Photo by Susan Valot.

By the end of the morning search at the arboretum, the group has found just one bumble bee, a rare one called Crotch’s bumble bee, or Bombus Crotchii. It is provisionally protected by law as California considers whether to declare it endangered or threatened. This is one of the bees that spawned the 2022 California Supreme Court ruling that bees can be treated as fish under the state’s environmental laws.

“An interesting thing about this bee is we know almost nothing about where it nests, and we know zero about where it spends the winter. So you can see how this would be a problem for environmental review,” Richardson explains. “We want to protect this bee from development, but we don’t know where it goes for six to eight months of the year. … There’s never been a report of hibernation by this bee, and there has never been a report of nesting by this bee until we found three nests already this year.”

Richardson says they have funding for the California Bumble Bee Atlas through at least next year. Volunteers can sign up and take training online. Richardson hopes that someday, they can expand the Bumble Bee Atlas nationwide.