Audrey Fusco can’t help getting excited at the sight of one monarch butterfly these days. In the spring sun in Bolinas, one poses briefly on the spire of a tall purple flower, wings aglow in the dappled light. “It does bring a sense of hope,” Fusco, a restoration ecologist with the Turtle Island Restoration Network, says. But it’s one of the only monarchs she’s seen today; in past years, more than a thousand monarchs visited. “Our baselines have all shifted now,” she says.

Scientists are all searching for hope for monarchs these days. The latest California count found 9,119 individuals—a 99 percent decline since the Xerces Society started monitoring in 1997 and found 1,235,490 butterflies. The U.S. Fish and Wildlife Service is now reviewing public comments on its December 2024 proposal to list monarch butterflies as threatened. Most scientists agree this has been a long time coming for a butterfly on the brink. 

This year, the context has changed dramatically: the Trump administration may threaten the chances of a once seemingly inevitable listing, as well as the Endangered Species Act’s very ability to protect species habitat. “My guess is that [the monarch listing]’s not going to fly,” says butterfly expert Stu Weiss, chief scientist at the environmental consultancy Creekside Science. But the proposal alone has intensified a fiery debate over how to protect monarch butterflies in the Bay Area. 

Of the 62 overwintering sites it identifies across California as “critical habitat,” 16 groves are in Alameda, Monterey, Santa Cruz, and Marin counties—including the grove in Bolinas where Fusco has been working. The designation prohibits federal agencies from doing anything that degrades the groves. 

Each grove is somewhere monarchs have congregated in thousands over the past decades. Every Bay Area grove also includes eucalyptus trees—the non-native species vilified across California for, among other issues, its tendency to catch fire. “It would be way more convenient for all of us if they used native trees,” says Emma Pelton, a conservation biologist at the Xerces Society. 

The Australian immigrants are not the easiest neighbors. Common eucalyptus species can shed tons of oily branches and bark every year, building ready kindling (though exactly how flammable they are is much debated). Each major fire, Pelton says, prompts a wave of inquiries to the Xerces Society, a nonprofit dedicated to protecting invertebrates. “[Landowners] love the monarchs, but they’re scared of eucalyptus trees, and eucalyptus trees’ reputation,” says Charis van der Heide, a biological consultant in southern California. Van der Heide has seen two monarch sites cut down already. In the wake of the Los Angeles fires, she expects her work protecting monarch habitat to get more complex. In the Bay Area, despite local protests, the federal Bureau of Land Management cleared twelve eucalyptus trees known as monarch roosts in the new Cotoni-Coast Dairies National Monument, citing “immediate risk of wildfire.”

Bolinas knows these tensions well. The Woodward Fire in 2020 burned within a hundred meters of the town, and made the risk of fire clear to this community of 1,176 people. Within six months, a group of citizens had organized a group, Wildfire Safe Bolinas (later the Bolinas Eucalyptus Project), to advocate for eucalyptus trees’ removal. They feared the next fire could engulf local eucalyptus stands, bringing flames into the heart of town. Even if groves escaped fire, eucalyptus trees lining the unincorporated community’s roads could drop branches and barricade escape routes. They put together plans to remove a grove that lines one of the two roads going in and out of the town.

Butterflies roosting on eucalyptus in Bolinas. All the Bay Area groves proposed as “critical habitat” contain these non-native trees. (Elizabeth Weber)

But Bolinas has also been a famed monarch hotspot for more than a century. Longtime Bolinas residents describe flocks so large they filled the sky, butterflies lifting off in masses so dense you could hear the collective beating of wings. When early frosts chilled the air, thousands of monarchs would tumble onto the road. Residents would fill enormous buckets and keep the butterflies at home until the air warmed up.

A quarter-century ago, the monarchs started to vanish across California. Tens of thousands became thousands; thousands became hundreds. In many places, hundreds became no monarchs at all. Mia Monroe, a former National Park Service ranger, counts around 20 places in Bolinas that once supported thousands of monarchs. She says about three still see butterflies. Some groves have been cleared. Others have suffered from lack of maintenance. 

Groups disagree about how much monarchs need the grove targeted by the Bolinas Eucalyptus Project, which Fish and Wildlife has not listed as critical habitat: Pelton described it as “one of the most important overwintering sites in the Bolinas area” in a 2023 email. The Bolinas Eucalyptus Project has referred to the site as “highly questionable monarch habitat.” 

Four years and several scientific analyses later, the eucalyptuses remain standing. They keep dropping branches. The road has shut down for 300 hours over the last two years, says ecologist David Ainley, a member of the Bolinas Eucalyptus Project. In January 2023, falling branches injured a young couple driving. Xerces Society volunteers had counted 432 monarchs there a few months earlier. 

It would help to understand why monarchs appear so drawn to eucalyptus. “I wouldn’t actually say that they like eucalyptus,” Peter Ibsen, an ecologist with the United States Geological Survey, says. “I would say eucalyptus are there.” When given the option, monarchs still prefer native trees. But they rarely have that option: eucalpytus—planted en masse by Gold Rush Australians along the West Coast, intended to provide timber and oil, and ultimately providing neither—now dominates California’s shoreline. 

What monarchs did before eucalyptus is “a million-dollar question,” says Sarah Gomes, a scientist with the Monarch Joint Venture, a national partnership that upholds the United States’ commitments to monarch conservation. Monarchs most likely landed on native trees like Monterey pine, Monterey cypress, or Douglas fir, but it’s hard to say (and Weiss says cypress and fir likely offered marginal habitat at best). Butterflies do not fossilize well. Colonization and genocide decimated Indigenous communities whose oral histories and traditional knowledge might have shed light on past butterfly behavior or the landscapes they lived in. The first European record of monarch overwintering dates back to the 1860s, in Monterey pines. 

So conservationists are working with what they know for sure. “Monarchs made their choice for eucalyptus,” says Weiss, who creates “designer habitat” for monarchs that includes eucalypts. “I’m more than happy to work with it.” 

Workers cut a gap in a dense eucalyptus forest at Point Pinole Regional Shoreline for “designer” monarch habitat. (Stu Weiss, Ph.D.)

Butterflies are loyal not just to eucalyptus groves, but to specific trees and even specific branches. Such spots offer “a core sheltering area for the species to ride out the difficulties of the winter season,” says Melissa Burns, the Western monarch coordinator at Fish and Wildlife. During that time, “they’re incredibly vulnerable.” The insects’ winter rest time helps them conserve energy and bulk up on nectar to prepare for the spring’s migration and reproductive orgy. 

What butterflies look for, likely, isn’t the eucalyptus itself but the “Goldilocks zone” of weather around the trees, says Ibsen, whose team spent two winters stalking monarchs at Monterey groves. The scientists arrived before dawn, kitted out with thermal cameras and binoculars, and watched how butterflies moved as the sun rose. Certain branches stood out—places where thin leaves shaded the area just enough to keep it cool, but not so cool that the cold-blooded insects never felt the sun; places where surrounding trees blocked the wind just right. The eucalyptusness of the eucalyptus trees had nothing to do with it. Sometimes, by random chance, the trees grew in the right patterns. 

“This is not some ancient co-evolved relationship,” Weiss says. “You can open up the site, and the wind will get in, and the monarchs won’t use them anymore.” As eucalyptus groves mature, the canopy becomes denser and less suitable for monarchs, unless people intervene.  “These eucalyptus stands need to be managed one way or another,” he says. 

People are still figuring out how to do that. “Different people are going to take different tacks,” says Pelton, who has convened a group of some 120 landowners across California to work on the problem. The monarch’s proposed listing brought fresh urgency to their work, as did the L.A. wildfires, which destroyed the second-largest overwintering site in L.A. County

Audrey Fusco, along with Ole Schell of the West Marin Monarch Sanctuary and other volunteers and staff with Turtle Island Restoration Network, are trying one strategy at the Bolinas grove where she spotted the monarch butterfly (a different grove from the site targeted by the Bolinas Eucalyptus Project). By planting native nectar plants like goldenrods, asters, and lilacs, and growing a windbreak of native trees around the remaining eucalyptus, they hope to improve this site for monarchs. 

Right: Ole Schell points to a eucalyptus grove at an overwintering site in Bolinas; natives like ceanothus (top left) feed the butterflies. (Elizabeth Weber)

Legally, a new “critical habitat” designation won’t change much here. This grove lies on private land, where the landowner has committed to restoring the area for monarchs. While the critical habitat designation highlights biologically important areas, Fish and Wildlife has no say over private land, unless landowners have federal money or are working with federal agencies in some other way. 

Burns says the agency remains on track to decide on the listing by December 2025. If the federal listing materializes—and if the Endangered Species Act continues to protect species habitat—it would put additional pressure on local governments to consider monarchs when approving building plans. “It’s not going to stop every tree from getting cut, but I think it could stop wholesale destruction,” says Pelton. 

Fusco and Schell have already seen what destruction looks like, when PG&E removed eucalyptus trees at this Bolinas site. (Ainley notes that falling branches from eucalyptus trees here have cut power for a day along this road.) Schell tried and failed to stop the removal of what he says was a key windbreak for the monarchs. “They still chopped down the tree,” he says. 

If the listing doesn’t happen—or if it does, but the ESA stops protecting habitat? Much is unclear, though people have begun asking about what that might mean. Likely, once more, the burden of protecting monarchs would fall on community stewards like Schell and Fusco. California’s state regulations, through the Coastal Commission’s “environmentally sensitive habitat area” designations and California Department of Fish and Wildlife’s species priority lists, offer some legal protections.

Right now, a federal monarch protection-in-process is still better than no protection at all, sources say. The Solano County Water Agency revised its Habitat Conservation Plan to include monarch butterflies and began planting milkweed at its nursery, intending to one day grow suitable pit stops for the butterflies. Pelton says many groups have begun reaching out to Fish and Wildlife to get agreements in place. State agencies plan as if the butterfly is already officially threatened, acting for the future conservationists still wish for. 

Burns, at Fish and Wildlife, already helps people help monarchs—advising them on how to deal with eucalyptus trees, among other issues. She expects to keep doing that work regardless of what happens with the listing. “I think of [the Endangered Species Act] as the emergency room,” says Mara Koenig, the national pollination communication coordinator at Fish and Wildlife. “We want to keep things out of the emergency room.”

Some people’s jobs would be easier if native monarchs stuck to native trees. But no one has a way to turn back the clock and prevent eucalyptus from entering California—or replace all eucalyptus overwintering groves today with native cypress, firs, or pines. So monarch scientists figure they have to make eucalyptus work—knowing both its dangers, and that no overwintering grove lasts forever. Weiss’s “designer habitat” uses hemispheric and LiDAR photography to inform where to plant trees or even use buildings to create microhabitats sheltered from wind. With different wind protection, managers could remove the dry kindling most likely to spark a fire—while keeping the specific trees that monarchs are keying on. 

At an overwintering site in Albany, Weiss’s team used a new student housing building, along with plantings like cypress, to create a wind-sheltered spot for monarchs to roost. (Stu Weiss, Ph.D.)

Tim Hyland, the natural resources program manager for California State Parks in Santa Cruz County, manages an iconic eucalyptus-dominated monarch grove at Natural Bridges State Beach. The grove has seen six fires over the last thirty years. State Parks regularly cleans up the debris to make future burns manageable. Keeping these non-native trees around means a lot of work. “In my purist world, I would personally be inclined to turn [the grove] into a lovely gully full of willows,” he says. 

But Hyland has watched the masses of monarchs that gather there inspire crowds of visitors annually. Maybe that’s worth the work to protect the eucalyptus, he acknowledges. “When you do zoom out, it’s a pretty small patch of territory to give up for a pretty big win,” he says.

Indeed, across California—as Pelton points out—it is a very small number of eucalyptus groves that must be protected to give West Coast monarchs a chance at survival. “Of course there’s a balance to be struck,” she says. Part of what conservationists like her must articulate is that landowners and monarch conservationists aren’t necessarily on different sides. “If a site totally burns down, that does not benefit monarchs. It doesn’t benefit human communities,” says Pelton. 

What comes next—as federal protections hang in limbo, as fire season arrives once more—is the endless work of figuring out how to strike that balance. For Fusco, the monarchs have broadened her perspective on what conservation demands. “We need to have a bigger vision for how we treat non-native species,” she says. “We are dealing with such a changed world.” 

How to Help Monarchs

Everyone can help monarchs in the Bay Area, regardless of whether they have a garden, says Emma Pelton. Here are a few strategies she recommends:

• Report monarch sightings on iNaturalist. This data helps scientists like Pelton know where to focus their conservation efforts.
• Plant year-round, ideally native, nectar plants in your garden. The Xerces Society has a list of recommended plants. Monarchs in the Bay Area need places to feed all the time.
• Plant native milkweed—cautiously. Planting milkweed outside of its range could throw off monarch breeding cycles, says Pelton. Check CalScape to see if where you live is in the historic range of native milkweed species, like broadleaf milkweed. If you do, visit your neighborhood nursery for milkweed cuttings—it’s a finicky plant to grow from scratch! 
• Advocate for pesticide-free neighborhoods. Consider asking your city council or other neighborhood groups to avoid using pesticides, especially neonicotinoids.