Pismo Beach saw fewer monarch butterflies this winter as experts warn population ‘in crisis’
The Pismo Beach Monarch Butterfly Grove in southern San Luis Obispo County hosted the second-highest number of overwintering monarch butterflies in California — but the imperiled species continues to struggle to survive.
On Tuesday, the Xerces Society for Invertebrate Conservation released its final tally of how many western monarch butterflies were counted by volunteers and staff across 400 sites in the state.
The nonprofit found that, overall, the butterfly’s overwintering population continued to be just 5% of what it was in the 1980s. Additionally, fewer of the monarch butterflies were counted in overwintering sites in 2023 than 2022, according to Xerces Society’s data.
“Western monarchs are in crisis,” said Isis Howard, an endangered species conservation biologist for the Xerces Society.
Western monarch butterflies migrate to groves of trees, typically eucalyptus or Monterey pine, to conserve energy during the winter months before dispersing to breed. California’s Central Coast seems to be particularly attractive for the migrating insects because of the mild climate and availability of groves, according to the Xerces Society.
In total, 233,394 overwintering monarch butterflies were counted at 256 sites in California. The Xerces Society conducted its annual count from Nov. 11 through Dec. 3.
The most butterflies were counted at a Santa Barbara County site owned by The Nature Conservancy, with 33,080 observed.
The Pismo Beach Monarch Butterfly Grove hosted 16,038 butterflies, making it the second-highest concentration of the insects in the state. Coming in at third was the Morro Bay Golf Course which had 10,029 monarch butterflies, according to the Xerces Society’s tally.
Overwintering population remains far lower than historical counts
The most recent figures are still above the catastrophic lows seen in 2018, 2019 and 2020, when fewer than 7,000 were counted in the state — but nowhere near the millions seen before the turn of the century.
More than 100,000 fewer monarch butterflies were counted during the 2023 overwintering tally than the 2022 count, according to the Xerces Society’s data. In 2021, 13,852 more monarch butterflies were counted in overwintering sites compared to how many were observed in 2023, the Xerces Society’s data show.
San Luis Obispo County’s overwintering monarch butterfly numbers saw similar downward trends.
In 2021, the Pismo Beach grove saw nearly 21,000 overwintering butterflies. That jumped to 24,128 butterflies counted in 2022 and then down to 16,044 butterflies in 2023, according to the Xerces Society’s data.
At the Morro Bay Golf Course, 8,464 monarch butterflies were counted in 2021 while 10,605 were counted in 2022. The population then decreased to 10,029 overwintering monarch butterflies counted in 2023, the Xerces Society’s data show.
Scientists and researchers remain concerned that the western monarch butterfly could topple toward extinction.
“We’ve bounced back (from historical lows), but we’re still not all the way back,” said Emma Pelton, senior endangered species conservation biologist with the Xerces Society. “All this bouncing around, were still bouncing around on really low numbers.”
It’s hard to tell what exact factors contributed to the steep decline in overwintering western monarch butterflies this year.
The 2023 counts may have been lower than 2022 because of devastating winter storms in January and March that could have wiped out some of the insect’s breeding population, as well as damaged the overwintering groves, according to Pelton.
“Last year’s winter storms meant we entered the spring breeding season with fewer butterflies and saw lower numbers this summer, so it is not surprising that the overwintering population is down,” Pelton said. “It’s difficult to predict how conditions during any single year will influence the population, but we do know that western monarch numbers need to be much higher before we consider this a recovery.”
Monarch butterflies are also threatened by habitat destruction, climate change factors such as extreme storm events, drought and heatwaves; pesticides and predation, according to the Xerces Society.
“There is still very little meaningful protection for migratory monarch butterflies and their overwintering habitat,” Pelton said. “Hopefully, the U.S. Fish and Wildlife Service’s upcoming listing decision under the federal Endangered Species Act will provide protection to the important places that monarchs rely on each winter.”
How you can help monarch butterflies
Everyone can take action to protect western monarchs and other wildlife. Here are some actions from the Xerces Socity to get started:
- View the Western Monarch Call to Action to learn more about priority zones and actions.
- Plant native milkweed and nectar plants in your garden and community spaces. (Milkweed should not be planted in overwintering zones.)
- Reduce or avoid herbicide and insecticide use, especially systemic insecticides.
- Share your knowledge and passion for monarch conservation with friends and family.
- Volunteer for a community science effort or local conservation cause.
- Take the Pollinator Protection Pledge to commit to working every day to protect pollinators and their habitats.
