Every fall dozens of monarch butterfly enthusiasts deploy to groves on the California coast to tally the orange-and-black insects who spend the winter clustered on tree limbs. In 2024 there were more volunteers than ever, but dreadfully few of the colorful butterflies to count.
On Dec. 9 a monarch lover named Saunie Holloway posted numbers from her annual pilgrimage to the Pismo Beach grove on the Western Monarch Advocates Facebook page. This grove is usually a favorite: More than 16,000 butterflies had adorned the eucalyptus trees there in 2023.
In 2024 volunteers counted fewer than 200.
“I just stood in the grove and wept,” Holloway wrote.
On Jan. 30 the Xerces Society for Invertebrate Conservation announced the official peak season numbers for Western monarchs: just 9,119 butterflies in 257 overwintering sites. It’s the lowest count since 2020, and the second-lowest since 1997.
The distressingly low numbers coincided with the U.S. Fish and Wildlife Service’s Dec. 12 proposal to list the monarch as threatened under the federal Endangered Species Act.
The population west of the Rocky Mountains is in especially dire straits. Western monarchs, already a fraction of the size of the eastern population, has shrunk to just 1% of its historic abundance. If nothing changes, the Service estimates, western monarchs face a 99% chance of going extinct in the next 50 years.
As numbers have plummeted, advocates have doubled down to save their western butterflies. This loose network of conservationists, educators, and citizen scientists — as dispersed as the butterflies themselves — have used technology and social media to connect and effectively share their messages. Both awareness and acres of pollinator habitat planted have expanded.
These efforts have been critical, says Isis Howard, an endangered species conservation biologist at Xerces Society.
But to help monarchs recover, she says, “We need to work at a larger scale and address widespread issues … beyond what voluntary efforts have been able to achieve.”
Complex Behavior, Complex Challenges
Most western monarchs overwinter at some 400 sites on the California and Baja coasts. They leave their coastal groves in late winter and early spring, dispersing into California, Oregon, Washington, Idaho, and beyond, breeding along the way. It takes several generations to make these yearly journeys; the butterflies who return to coastal groves are not the same individuals as the ones who left the year before.
The reasons for western monarchs’ decline are complex. Pesticides, habitat loss, and climate change are the most oft-cited factors. With numbers so low, other factors — predators, disease, and extreme weather events, for example — loom larger.
This January, volunteers with the Western Monarch Count made a horrific discovery near the Pacific Grove Monarch Sanctuary: dozens of monarchs scattered across a lawn, spasming as they died. Testing revealed their bodies contained an average of seven different pesticides.
The Fish and Wildlife Service has called for information and input on pesticide use as part of its public comment period on the animals’ proposed Endangered Species Act listing, which runs through March 12.
Climate change is also affecting monarchs across their range. In January the Palisades Fire destroyed monarch habitat in lower Topanga Canyon in Los Angeles. More severe winter storms also threaten overwintering butterflies. Howard of Xerces Society says extreme heat likely affected the third and fourth generation of monarchs last year.
Tom Landis, a retired U.S. Forest Service nursery specialist, says climate change isn’t just making it harder for monarchs to thrive; it’s also changing their behavior.
Landis lives in southern Oregon, where he teaches workshops to help people plant critical “stepping stone” habitat for migrating monarchs — milkweed and nectar plant waystations within densely developed areas. He says he’s honed in on a bottleneck that may be preventing monarchs from making it to his region in the first place.
To successfully breed, monarchs who leave their overwintering sites in California must lay their eggs on milkweed — the exclusive diet of their caterpillars. “I don’t think they’re finding it,” says Landis. This is because the butterflies are leaving earlier than they used to.
Native milkweeds die back in winter and put out fresh new leaves in spring, too late for these early season migrants. Landis thinks we can — and should — help accommodate the butterflies.
Two California species emerge before all the others. Planting these in key places could help that first generation of monarchs as fly inland, Landis explains.
“We need to get them out on sites along the coast range and the interior valley so that when monarchs come out, they have some place to lay their eggs.”
Xerces Society has named planting pesticide-free early season native milkweed and nectar plants in the “early breeding zone” in California a top priority for recovering Western monarchs. Landis has been traveling to California to collect seeds, and with the help of a master gardener in Yuba City he’s developed techniques for successfully growing them in pots. Now California nurseries and master gardeners are helping him propagate them. The Forest Service has provided some funding to cover basic expenses.
Landis grew up in Wichita, Kansas, where monarchs were “annoyingly common.” He became enchanted with them after moving to the Pacific Northwest, where sightings are rarer, and co-founded Southern Oregon Monarch Advocates. He says isn’t surprised so many people are willing to help with his project.
“Everybody loves monarchs,” he says. “I call them charismatic microfauna.”
Calling All Citizen Scientists
Helping western monarchs will rely on filling in knowledge gaps about their movements and behavior — a difficult task with such a widely dispersed population. Xerces Society is supporting several efforts to better understand key characteristics, including fire risk, at overwintering groves. One project is experimenting with tiny GPS units that track butterflies as they migrate.
From the hundreds of volunteers with Western Monarch Count to backyard gardeners, citizen scientists have played a key role in helping unravel monarch mysteries over the past decade. David James, an associate professor at the Department of Entomology at Washington State University, has enlisted the help of citizen scientists to tag and track Western monarchs. Among other things his work has helped illuminate the migration routes of thousands of butterflies from Washington state.
The Fish and Wildlife Service wants people to help save monarchs, and its proposed listing is purposely flexible so people can actively engage in conservation. The listing may contain a “4(d) exception” — named after a section of the regulation that would otherwise prohibit handling, netting and small-scale captive rearing of monarchs.
Robert Coffan, who cofounded the organizations Southern Oregon Monarch Advocates and the larger Western Monarch Advocates, says he’s pleased the Service’s proposal doesn’t prohibit citizens from tagging butterflies. Affixing tiny wing tags on monarchs to help trace where they go has already yielded important insights about western monarch movements and behavior.
Coffan says hands-on citizen science can also light the passion of young conservationists by giving them the “monarch miracle.”
“To have them write the data down for the tag and let them know they are part in research for the whole country, they absolutely love it,” he says. “And if one of their tags is found, it’s absolute mayhem.”
Susie Vanderlip, a public speaker and monarch advocate who lives in Orange County, California, hopes the federal listing will prompt California to lift its restrictions on handling and tagging monarchs, which have been in place since 2021.
“Citizen scientists keep the focus on the value of monarch butterflies,” says Vanderlip, who has connected with monarch experts from around the country and exchanges information through her Facebook page. “Not just the value, but the iconic beauty and the spirituality that they represent to so many people.”
Vanderlip has accumulated anecdotal knowledge about Southern California monarchs, but she would like to see a study that tracks monarchs from her part of the state.
“Nobody’s tagged a bunch of monarchs in Southern California to see where they go. So we don’t know,” she says.
A Chain of Pearls
Loss of habitat is one of the primary reasons for the monarchs’ decline. A big factor is the dramatic increase in so-called “Roundup Ready crops,” bred to be resistant to the pesticide glyphosate. When Roundup is applied to herbicide-resistant corn and soy, it kills everything else that might compete with the crops, including milkweed and nectar plants.
Logging, urban sprawl and development have also displaced pollinator plants.
While replanting habitat — including both milkweed and the nectar plants that adult butterflies need — will likely not by itself save the monarch, it’s a critical piece of the puzzle and something nearly everyone can do.
“Having a chain of pearls of connected habitat in urban areas is really important,” says Coffan, adding that “waystations” along migratory routes can help ensure monarchs complete their migratory journeys to the coast. “Every single one of the monarchs in those [coastal] clusters came from somewhere else, either in California or from one of several other states.”
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In Portland, Oregon, where monarch sightings are relatively rare, Ida Galash is on a mission to expand pollinator habitat.
Galash fell in love with the showy butterflies in 2019. She began documenting caterpillars and adult butterflies that visited her garden and posting the sightings to her neighborhood NextDoor group. Eventually she launched a Facebook Group called Portland Monarchs. Still not satisfied, she began stocking seed libraries with free native seeds and information sheets.
“I can’t save the monarchs myself,” says Galash. “I try to take down barriers and make it easier for other people to create habitat.”
In recent years she’s given away more than 4,000 seed packets for native showy and narrowleaf milkweed and 30 kinds of native, nectar-producing flowers.
Her social media posts have dispersed seeds of their own.
In December a woman named Pam saw Galash’s post about the dismally low overwintering numbers.
“After a few days of wringing her hands, she decided she had to do something,” says Galash. Pam, who lives in Salem, Oregon, posted on her local Buy Nothing group, offering to help anyone who wanted to replace their lawn with pollinator habitat. Twenty people responded. Pam purchased seeds and 300 native plants and recruited people to help install the new gardens.
“She was right on it,” says Galash. “One person can really make a difference.”
