Monarch butterfly count plummets in SLO County. ‘Feels like a punch to the heart’
Fewer-than-usual monarch butterflies migrated through San Luis Obispo County this winter, according to data from the conservation-focused nonprofit the Xerces Society.
“It feels like a punch to the heart,” Xerces Society conservation biologist Isis Howard said. “It’s scary because you don’t want to lose that phenomenon.”
Western monarch butterflies migrate from Arizona, Nevada, Oregon, Washington, Idaho, Utah and inland California to coastal California to stay warm and conserve energy during the winter.
The Pismo State Beach Butterfly Grove only hosted 556 monarchs at the peak of the 2024 season — a steep decline from the 16,044 butterflies counted in 2023, according to Xerces Society data.
The all-time lowest population size was reported in 2020 in Pismo Beach, when only 199 butterflies were counted at the overwintering site.
Pismo Beach’s butterfly count matches migration data from the rest of the West Coast.
Only 9,119 butterflies were counted at West Coast overwintering sites during the 28th annual Western Monarch Count in 2024. That’s significantly lower than 2023, when volunteers counted 233,394 butterflies at the 257 overwintering sites.
2020 was the worst year for the rest of California, too, when only 1,901 butterflies were counted across all overwintering sites, according to the Xerces Society.
In light of the disappointing numbers, Howard encouraged people to spread the word about the challenges monarch butterflies face and advocate for the protection of their habitat.
“It’s purely remarkable how a tiny creature that weighs less than a paperclip can travel across skies for hundreds and thousands of miles and survive that,” Howard said. “We can all resonate with challenges and obstacles coming up, and it’s surprising but also hopeful to see a tiny little creature like this demonstrate such strength and resilience.”
Why is the butterfly population declining?
Though the number of monarch butterflies migrating through California has fluctuated over the past decade, one trend is clear — the Western Monarch butterfly population has declined by more than 95% since the 1980s, Howard said.
With such a drastic population loss, the remaining butterflies are heavily impacted by the weather, she said.
Drought and heat struck California during late summer and early fall, creating difficult conditions for the monarchs to survive in.
In fact, California set new heat records every July during the past 10 years. Meanwhile, much of the western breeding areas for the monarchs face some level of drought, which reduced the amount of milkweed and nectar plants available to the butterflies, Howard said.
“This highlights some of the impacts of climate change during the last decade,” she said.
Outside of the weather, habitat loss and a decline in milkweed and nectar plants has reduced the butterfly population, Howard said. Meanwhile, pesticides dealt a blow to butterflies, too.
During a difficult year for the migrating insects, the federal government proposed listing monarch butterflies as threatened under the Endangered Species Act. The proposal includes designating 4,395 acres of critical habitat for the western migratory population in seven California counties — including the Pismo State Beach Monarch Butterfly Grove.
Howard said this designation is critical for protecting monarch butterflies, as it will create a legal mechanism for preserving overwintering sites.
“This is what we’ve been looking for,” she said.
The U.S. Fish and Wildlife Service is accepting comments online until March 12 about the designation.
“I really encourage people to engage in this process,” she said. “In a perfect world, we get everyone on board for monarch conservation.”
How to support monarch butterflies
There’s good news: Everyone can do something to support the monarch butterfly population, Howard said.
If you have a garden, Howard recommended planting native milkweed or nectar plants that bloom during the fall, winter and early spring.
“That’s when these monarchs are migrating hundreds of thousands of miles,” she said. “They need nectar.”
If you live near an overwintering site like the Pismo Beach Butterfly Grove, however, avoid planting milkweed and instead opt for native nectar plants, she said.
If you don’t have a green thumb or access to a yard, Howard said you can take photos of butterflies and milkweed and post them to databases like iNaturalist to support scientific research or advocate for the conservation of local butterfly habitat.
She also encouraged people to volunteer with the Xerces Society to collect data about monarchs and spread the word about challenges the insects face.
“A lot of people don’t know about the plight of monarch butterflies,” she said.
If you’re feeling creative, you could even give potted nectar plants or seed packets to friends and family as gifts during the holiday season, she said.
“Everyone can find some sort of way to participate,” Howard said.
