On a warm August morning, Brissa Garcia inspected a bee hotel, a large wooden box mounted in a wetland near the Klamath River in Northern California. As the fragrance of mint rose from the soggy ground, a few bees buzzed around circular openings on the front of the box.
“Sometimes you can see them carrying in leaves, grass hairs,” said Garcia, a wildlife biologist with RES, the company charged with restoring three former reservoirs along the Klamath River in Northern California and Southern Oregon. “They could use plant hairs, mud, pollen for nesting material.”
RES and the Yurok Tribe have been planting billions of seeds and thousands of trees, shrubs, and flowering plants in the reservoir footprints. One goal is to support pollinators, which rely on nectar and pollen for food. Now, wild bees are helping the restoration team tweak their palette of native plants.
As bees hovered around her, Garcia carefully opened the box and pulled out a long clear tube, filled with crushed leaves, bands of bright yellow pollen, and at least one tiny bee egg.
“What we're monitoring for are solitary bees and cavity nesting bees,” said Jenny Wallgren, regulatory manager for the Lower Klamath Project at RES. “They don't make hives, but they do nest in little single cavities that we can replicate using these tubes.”
RES has partnered with a Belgium-based company called BeeOdiversity to install six of these “BeeOtels” in the former reservoirs, which were drained in 2024. This one was in a spring-fed area called Long Gulch, near the former Iron Gate dam. The green swath stood out against the surrounding landscape, which had dried to a golden brown.
During the field season, Garcia checks the hotels every week and sends some of the tubes to a lab for DNA analysis. The pollen helps the team answer several questions.
“What pollinator species do we have on the site and how is that changing year to year?” Wallgren said. “And then what is the difference in what plant species they're visiting? What are they making their nests out of? What are they feeding on?”
RES can compare the information the bees are bringing in with weather data and plant monitoring data. Over time, the pollen data could help paint a more nuanced picture of what’s happening on the ground, Wallgren said.
Recruiting pollinators
BeeOdiversity started with a Belgian scientist who figured out a methodology for analyzing bee pollen collected by honeybees, which live socially in hives.
“Bees collect millions of environmental samples every day,” said David Strelneck, North American coordinator at BeeOdiversity. “So when we are analyzing the site across several miles, for example, you're getting incredibly detailed data.”
One of the company’s first projects in North America was at Lakeside Farms on the east side of Klamath Lake, where wetlands have been restored. Strelneck said pollen analysis from the honeybee hives has helped track the project’s success.
“The first three and a half years, the number of different plant species at Lakeside Farms on a two-square-mile site increased 93%,” Strelneck said. “The farm owners now have hard data on that.”
Pollen analysis can also reveal contaminants. At Lakeside Farms, managers were spraying an herbicide to control an invasive plant called yellow flag iris.
“Because of the bee data, they changed the way they apply the pesticide,” Strelneck said. “And we saw a huge drop in the incidence of the [chemical] in the bee results a year later.”
More recently, BeeOdiversity began deploying BeeOtels to collect data from wild solitary bees, which have much smaller ranges than honeybees. Some of the first were installed in the summer of 2025, on land RES is restoring.
OSU Extension resources support restoration
Habitat loss is the biggest threat to native bees, said Lincoln Best, taxonomist for the Oregon Bee Atlas at OSU Extension Service.
“If you convert an area of the High Desert into hay production, you're converting the ecosystem into a different land use, which isn't biodiverse,” Best said.
Habitat restoration offers an opportunity to help pollinators by including the flowering plants they need most, and OSU Extension Service has developed several resources to make sure this chance isn’t missed.
The program has recruited hundreds of citizen scientists to fan out across Oregon to search for native bees and document the plants they visit. Last year alone, volunteers documented 34,000 bees on 4,600 plants.
Their data feeds Melittoflora, a website where anyone can explore the relationships between Oregon’s hundreds of native bees and the plants they have visited.
“One of my foundational hopes for our program was to inform restoration using our massive and growing data set,” Best said.
Restorationists can look up the plants they intend to use and learn which bees are known to visit them. They can also look up what bees are documented in an area and select plants especially for them.
The Klamath region is home to a diversity of native wild bees, including specialists that rely on a single flower species. The presence of these bees can help validate the success of restoration projects, Best said. “Once you get the really rare things in there, you know you already have the more common and widespread things.”
Supporting pollinators through the summer
In August, some flowers were still blooming in the wetland at Long Gulch. Garcia pointed out one called beggarticks with orange-yellow flowers and sticky, barbed seeds.
“You just have to look at it, and it sticks to you,” Garcia said.
To decide what to plant, RES has drawn on staff botanists, local agency and tribal partners, historical records and plant observation databases. The goal is a mix of plants that grow in the area and that support a variety of pollinators.
The BeeOtels are just one tool RES uses to inform restoration, Wallgren said. They capture data from certain cavity-nesting species, leaving out the many native bees that nest underground.
Even so, the pollen data has already provided some important insights.
“We learned that toward the end of [last] season, when everything else is drying up, our native bees were largely visiting star thistle, which is highly invasive and one of our high priority targets to remove,” said Wallgren. “We need to replace that instead of just removing it….if we want to keep our pollinators happy.”
RES crews have continued planting this fall. By spring, many of these plants will be abuzz with wild bees busily collecting pollen for their young — and data for land managers.
