June 4, 2025The news wasn’t expected to be particularly positive, but few thought it would be this dire.
This January, the Xerces Society published its 28th annual Western Monarch Count, reporting a peak of 9,119 overwintering butterflies along the California coast. This is the second-lowest recorded overwintering population since tracking began nearly 30 years ago and aligns with the U.S. Fish and Wildlife Service’s December 2024 proposal to list monarchs as threatened under the U.S. Endangered Species Act.
Down from 335,479 butterflies in 2023 and 233,394 last year, this crash in the monarch population is alarming.
“People depend on pollinators, they’re really important animals,” said Angela Laws, Endangered Species Conservation Biologist with the Xerces Society, an international nonprofit committed to protecting the natural world through the conservation of invertebrates and their habitats. “So much of our food is reliant on pollinators. Beyond that, pollinators are essential to so many natural ecosystems that we enjoy recreating in, support biodiversity, and provide us with important services like carbon sequestration.”
In helping to do its part, River Partners set an audacious goal to plant 15 million milkweed plants across California by 2030 to support Western monarchs and other pollinators. And because milkweed is the only plant that monarch’s lay their eggs on and the resulting caterpillars feed on, to help achieve this goal, River Partners will plant milkweed in virtually every future restoration project throughout California.
Additionally, River Partners is planting thousands of other pollinator-friendly plants at restoration sites statewide to support a wide range of pollinators.
According to the Xerces Society’s Priority Action Zones in California for Recovering Western Monarchs, the 450-mile-long Central Valley is a critical breeding zone. And, because monarchs follow rivers and the native vegetation and food they grow along their migration from the California coast to the Rocky Mountains, restoring Valley riverways is essential for monarch recovery. And within this area, the San Joaquin Valley is where we are focused on most of our monarch recovery work.
As part of the largest coordinated monarch recovery program in the West, thanks to a generous grant from California Department of Fish and Wildlife (CDFW), we planted over 30,000 milkweed plants, as well as thousands of other pollinator-friendly vegetation, across eight priority locations and nearly 600 acres statewide (see map). Multiple years of monitoring shows signs of hope, as monarchs and other imperiled pollinators are coming back to historic habitat they haven’t visited in decades.
River Partners Associate Director of Restoration Science Michael Rogner said the urgency of 2030 reflects the peril the monarch butterfly is in.
“The overwintering counts have been all over the board, but mostly terrible,” Rogner said. “We don’t have time to figure out every little thing about how to restore habitat for the species, we just have to get it done, so we’re going to learn by doing, doing it a little differently every year, and getting better.”
When it comes to planting milkweed and other vegetation that makes up pollinator habitat, it’s not just planned and current restoration that are valuable—the Western monarch also needs our help in places that have already been conserved.
“It’s critical that monarch conservation happens everywhere, but it’s essential that we leverage conserved lands that are not being blanketed with pesticides as sites for these projects,” Rogner said. “Every parcel of a state park, state wildlife area, and national wildlife refuge is a monarch restoration project waiting to happen, and we need to be working more with our Tribal partners who have stewarded these habitats for generations.”
Partnerships with the Xerces Society and the California Department of Fish and Wildlife also help with this extraordinary lift boosting California’s climate resilience, adapting to weather whiplash and dramatic swings between drought and flooding, and reducing pesticide use to bring the Western monarch butterfly back from the brink.
“The Xerces Society are the experts, they spend their lives thinking about this stuff, so why do we want to spend all of our time trying to relearn what they already know when we can just go to them?” Rogner said. “And then when we have results, we can go back and ask them to help us interpret what this means.”
“CDFW supports the creation of monarch habitat, such as planting milkweed and diverse nectar plant species throughout the state as a mechanism to help bolster the species’ declining population,” CDFW’s Pollinator Coordinator Hillary Sardiñas said. “It will take the coordinated effort of conservation agencies and organizations across California to fully act on a task this daunting. The Western monarch and other pollinators are depending on us.”
Additionally, our nonprofit native seed venture, Heritage Growers, is providing milkweed seeds and plants for agencies, organizations, and restoration efforts throughout California—an estimated 25 million milkweed seeds this year alone. Heritage Growers was instrumental in the historic restoration of native habitat along the Klamath River. After the largest dam removal project in this country’s history, Heritage Growers provided millions of native seeds and tens of thousands of native plants to spur the return of native grasses, plants, and trees that will complete the river habitat’s rebirth.
“When we work together, we can get a lot more done,” said Laws. “One of our valued partnerships is with Heritage Growers, which is one of the suppliers of plants that we distribute every year through our habitat kit program.”
It’s a hefty task before us, and River Partners is committed to doing what it can throughout California to ensure this beloved butterfly has a thriving future.
“It’s a species people love, and it inspires,” Laws said. “People are passionate about monarchs in a way they aren’t about many other insects.”
Here’s what River Partners’ restoration scientists and biologists are doing this year across the state to help the Western monarch and other important pollinators, where milkweed and other nectar-rich plants are being placed in the ground.
Northern California
At our 150-acre Rancho Breisgau site, located about five miles east of Cottonwood at the confluence of Battle Creek and the Sacramento River, we planted 1,200 plugs of milkweed over a total of 130 acres. This included narrowleaf milkweed and woolly pod milkweed (the latter of which is a new species for River Partners projects). Both milkweed species were grown out by Heritage Growers and paid for by the Xerces Society.
That’s in addition to 100 showy milkweed rhizomes we planted here last fall. All the milkweed for this project was donated by the Xerces Society and is incorporated into a project spanning 25,000 plants over 150 acres.
It’s not just milkweed here, though. Other pollinator plantings this spring incorporated California rose, clematis, western goldenrod, mugwort, California blackberry, and coyote brush, which are also important habitat, food source, and cover for rabbits, foxes, raccoons, and a host of small rodents. Additionally, tree species were added at lower densities to provide structure and to prioritize flowering shrubs and forbs for the pollinators. Species selected for this project have variable flowering windows and will provide floral resources for pollinators year-round.
San Joaquin Valley
This spring, River Partners seeded pollinator zones at the 935-acre Panorama Vista Preserve, which straddles both sides of the Kern River in Bakersfield, which we’ve been restoring since 2009, enhancing previously restored riparian forest areas with pollinator-friendly flowering plants. In 12 plots over about 2.5 acres at this southern San Joaquin Valley site, we seeded narrow milkweed, California poppy, lacy phacelia, yarrow, bladderpod, common buttonbush, and vinegarweed to target a diversity of pollinators, from native bees and moths to butterflies, including the imperiled Western monarch.
We’re also working with the Xerces Society and Heritage Growers to provide milkweed to directly sow into the ground at restoration projects. To reach 15 million milkweed, we need to mass-produce it from seed and not rely merely on potted stock and rhizomes.
Southern California
River Partners planted rush milkweed at our Finney-Ramer Unit restoration project, located southeast of the Salton Sea in the Imperial Valley, this spring. This species was new to our plant palette in 2023 and attracted monarch butterflies within a year. Because of this region’s intensely hot and dry summers, River Partners will pause planting during the hot summer months and then resume in the fall, when we plan to place more than 3,300 plants in a 14-acre field at our 1,500-acre Finney-Ramer restoration near the Salton Sea.
To support the recovery of pollinators, we will plant native milkweed and other nectar-rich plants like desert willow, salt heliotrope, desert lavender, blue palo verde, and salt marsh fleabane. With flowering periods throughout the year, we hope these plants attract a variety of bees, moths, and butterflies that rely on diverse native habitats.
Found among pollinator habitat at a pair of our Southern California restoration sites were a couple of key pollinator species! Last month, The Nature Conservancy (TNC) identified an endangered Crotch’s bumble bee at Capinero Creek, which lies just east of the historic Tulare Lake on the southern end of the Sierra outside of Bakersfield. As a project partner for this 157-acre restoration project, TNC staff observed the bumble bee while out monitoring the site with a local group. And pygmy blue butterflies were found at our Finney-Ramer Unit project in the Imperial Valley, proving once again that wildlife, including pollinators, tell us our restoration is working.
