Right about now, you may be seeing spotted orange butterflies drifting overhead or amongst your garden’s flowers. Fall in Marin means the arrival of monarch butterflies, a favorite winter-to-springtime resident and vital pollinator.
Even basic biological facts about the monarchs can be incredible. Every year, the butterflies perform a massive migration hundreds or thousands of miles across the country. But no one butterfly will migrate twice. Actually, only every fourth or fifth generation of monarch will migrate — imagine walking the same 1,000-mile route that your great-great-grandparents did, with no roadmap. Add onto that a boggling lifespan: Monarchs that migrate live 6–9 months, while their descendants/ancestors that hatch during spring and summer spend just 2–6 weeks as full-fledged butterflies.
Monarch butterflies keep you guessing. But one fact is clear: Western monarch populations have declined severely in the past few decades, and even more acutely in the last few years. In response, conservation organizations and community members are stepping up to protect them.
Why are monarchs in Marin?
Western monarchs migrate to coastal California for “overwintering” sites, places where they can tough out the winter. Western monarch butterflies (distinguished from eastern monarch butterflies by their relative position to the Rocky Mountains) overwinter in places like Stinson Beach, Bolinas, Muir Beach and the Headlands, plus down the coastline all the way to Baja. By early spring, the butterflies fly inland to breed, including in spots like Corte Madera, Novato, Santa Rosa and the Oakland Hills, before dispersing around western states.
Monarchs used to be so abundant in California that early newspapers described tree branches breaking under the butterflies’ weight. An estimated 4.5 million western monarch butterflies migrated to California in the 1980s. Counts from last year put the population at 233,400, but not even four years ago, observers feared extinction for the western monarch.
In 2020, volunteers counted fewer than 2,000 overwintering monarchs across all of California. And that’s not a defect of lower pandemic-era participation: More overwintering sites were monitored during the 2020–2021 count than the year before.
Despite these dismal numbers, neither the monarch nor its admirers were going to admit defeat.
Community science
“It starts with that urge to protect something beautiful that’s a part of our lives,” said Mill Valley’s Mia Monroe. “And then it can take many forms, and some people want to help by collecting data.”
In 1997, Monroe and a handful of scientists co-founded the Western Monarch Count, a yearly monitoring effort that Monroe still coordinates, with the help of the Xerces Society for Invertebrate Conservation and about 400 volunteers across California. Volunteers survey monarchs’ overwintering habitats three times per year, collecting data that’s consulted by scientists, media outlets and policymakers.
When the Count recorded just 2,000 overwintering monarchs in 2020, concerned citizens sprung into action.
“No one waited to be told what to do,” said Monroe. “There was this huge flurry of energy.”
Folks across the county, the state and the country were double-checking the numbers, planting native flowers for butterfly and caterpillar food, reducing pesticides and telling everybody and their brother how to help the monarchs. This reaction, driven by concerned citizens, exemplifies a growing avenue for environmental conservation called community science.
Community science refers to regular people participating in scientific research, and this participation could be key to saving species threatened by a rapidly changing environment. Though community scientists may have different day jobs, they’re not novices. Volunteers for the Western Monarch Count, for instance, are trained in data collection and follow rigorous guidelines.
Another local community science organization, the Marin Monarch Working Group, has been finding actionable ways to improve monarch outcomes in Marin since its founding in 2019. Meeting monthly on Zoom, they get in the weeds — sometimes literally — to improve pollinator gardens, educate community members and advocate for the butterflies. The group successfully lobbied Marin County to ban nurseries from selling tropical milkweed, a nonnative plant that confuses well-meaning humans and harms monarchs, which exclusively lay eggs on native milkweeds.
Getting to the root, by planting
Like many other species, monarchs face challenges like habitat loss, poisoning by pesticides, vulnerability to climate change and other threats. But a unique hurdle for these butterflies is in the fate of a single plant: milkweed.
Milkweed is intertwined with the monarch’s life cycle. The butterflies lay their eggs on the plant, and growing larvae munch on its leaves before hanging from it as a chrysalis.
In Marin, milkweed planting efforts are rebuilding lost habitat in the inland regions that monarchs will visit after overwintering. Around Novato’s Mount Burdell Open Space Preserve, Marin County Parks has set up sites for new milkweed growth at Joske Grove and the San Carlos Drainage, and planting events draw volunteers during wet winters.
This project is no small feat. After the monarch population crisis of winter 2020–2021, a now-defunct community science program called the Marin Milkweed Monitors combed Marin County’s public lands for milkweed growth. With this volunteer-collected data and research into historical growth by parks employees, Mount Burdell was determined to be the most auspicious site for planting. Golden Gate Parks Conservancy secured a grant from the Wildlife Conservation Board, and a partnership with Marin County Parks got folks to work planting milkweed and nectar plants. Another group of dedicated volunteers, the Marin Master Gardeners, potted the plants.
“It’s such a clear directive from a restoration standpoint,” said Aja Mathews, nursery specialist with Marin County Parks, who oversees the milkweed project on Mount Burdell. “We know the problem, we know some concrete steps to take.”
On the flip side of milkweed habitat restoration, overwintering sites also need attention. During winter, monarchs gather in roosting trees along the California coast. These tend to be eucalyptus trees, but also Monterey pines and Monterey cypresses. Clearing out debris from the understory and planting nectar plants nearby are two ways to improve the habitat and monarch outcomes.
What can you do?
If you want to get involved, monarch conservation can start in your backyard. Gardens with nectar-rich plants provide crucial food for monarchs. Mathews recommends native nectar plants like California fuchsia, goldenrod, native sages, monkeyflowers and buckwheats. Avoid pesticides.
Want to plant milkweed? First, think carefully about where you live. It’s not recommended to plant milkweed within two miles of the coast or at overwintering sites, as it interferes with overwintering and can cause monarchs to breed prematurely. But if you live in inland Marin, more than two miles from the coast (near the bay is okay), then planting native milkweed can create more sites for the butterflies to lay their eggs. Ask your local nursery about narrowleaf milkweed, Marin’s native species, and don’t panic when it turns brown in the fall, when native milkweed goes dormant. Steer clear of tropical milkweed, which disrupts breeding and exposes monarchs to a deadly parasite.
Aspiring community scientists can get involved in the Western Monarch Count or, make a difference in your neighborhood with the Marin Monarch Working Group. Stay in the loop about habitat restoration opportunities with Marin County Parks by subscribing to the One Tam newsletter at onetam.org/volunteer. And next time you see a monarch in your garden, or a patch of native milkweed on a hike, consider snapping a picture and uploading it to the app iNaturalist, a social network where users contribute observations of living things. Scientists are actively using iNaturalist contributions in research about monarchs.
The future looks optimistic for western monarchs, but they’re not out of the woods yet. One big storm or heavy wildfire smoke could wipe them out. The ranks of community scientists, researchers and conservation organizations give the insects a fighting chance.
Overwintering Site, Restored
“It’s poetic in itself,” said Ole Schell about watching the monarchs rebound on his family’s ranch in Bolinas. “It takes your breath away to see an explosion of monarch butterflies.”
Schell’s family ranch was a historic overwintering site for western monarchs. In childhood, Schell saw thousands of monarchs line trees on the property, but in adulthood the number dwindled to zero.
Research led him to Mia Monroe and the Xerces Society for Invertebrate Conservation. Xerces offered guidance — “after gauging my seriousness,” Schell said. The property has a water source and an ideal eucalyptus grove where butterflies could cluster, shielded from the wind by its bowl shape and warmed by sunlight, as it faces south. Xerces said he could fit 1,200 native nectar plants on the ranch as a food source.
He got to work in 2021. A partnership with the nonprofit Guardian Grange connected combat veterans to the project to execute the land management — a labor that helps them reintegrate into society and process trauma. Hundreds upon hundreds of plants went up, along with a tall deer fence.
Immediately, there was an increase in pollinators. The bees came first. Then, in the winter, monarchs started flying in.
With monarchs back overwintering on the property, the next goal is getting clusters of 500 to 1,000 butterflies at a time. The sanctuary keeps expanding, and Schell established a nonprofit called West Marin Monarchs, which organizes art shows, panels discussions, community planting days and school field trips to the ranch. The board of directors includes notable local and state leaders, like Chef Alice Waters and the chair of the California Energy Commission, David Hochschild.
Learn more: westmarinmonarchs.org
Western Monarch Quick Facts
Lifespan: 2–6 weeks, or 6–9 months for migrating monarchs
In Marin: October–February
Overwintering regions: Coastal California and Baja
Overwintering sites in Marin: Stinson Beach, Bolinas, Muir Beach, Marin Headlands
Spring/summer breeding regions: Washington, Oregon, Idaho, Nevada, Arizona, California
Feed on: milkweed as caterpillars, nectar plants as adults
Estimated population: 233,400*
Historical population height: 4.5 million in 1980s
* Western monarch count estimates are all sourced from the Western Monarch Count. Learn more at westernmonarchcount.org
