Western Monarch Butterflies Record a Worrisome Decline in California

The Xerces Society, a conservation group dedicated to invertebrate protection, announced disheartening news for insect enthusiasts and conservationists: the 28th annual Western Monarch Butterfly Count has revealed the second lowest number of overwintering monarchs ever recorded since the count began in 1997.

This year, a mere 9,119 butterflies were spotted in California, a sharp decline from the past three years, when more than 200,000 overwintering western monarchs were observed each year. It is only slightly above the all-time low of less than 2,000 monarchs in 2020, and well below the millions of butterflies observed in the 1980s that scientists consider a stable population level.

“The population’s size is extremely concerning,” said Emma Pelton, an endangered species biologist with the Xerces Society for Invertebrate Conservation. “We know small populations are especially vulnerable to environmental fluctuations, and we think that’s what happened this year. The record high late summer temperatures and drought in the West likely contributed to the significant drop-off we saw in the third and fourth breeding generations.”

Every autumn, typically around October, Western Monarch butterflies commence their migration to Central Coast regions like the renowned groves at Natural Bridges State Park, clustering densely in trees for the winter months.

“A lot of people care about monarchs. Voluntary efforts like pollinator gardens and restoring habitat are probably a reason they aren’t in worse shape,” said Isis Howard, coordinator of the Western Monarch Count with the Xerces Society. “However, these actions are not enough. To help monarchs recover, we need to work at a larger scale and address widespread issues like pesticide contamination and climate change that are beyond what voluntary efforts have been able to achieve.”

In a move that underscores the critical status of the Western Monarch, the U.S. Fish and Wildlife Service proposed listing the butterfly as a threatened species under Section 4(d) of the Endangered Species Act in December 2024. The public has until March 12 this year to submit comments on the proposed listing, a move that could herald new federal protections for the iconic insect.

Randy Widera, Director of Programs for California State Parks Foundation, expressed the organization’s distress over the count’s findings. The Foundation has been instrumental in conserving monarch groves within state parks and advocates for the butterfly’s threatened status, highlighting the species’ emblematic presence in California’s natural heritage.

This year’s largest monarch clusters were in Santa Cruz County, with three of the top four sites within California State Parks-managed areas. These spaces, such as Lighthouse Field State Beach and Point Lobos State Natural Reserve, continue to play a vital role in supporting the overwintering monarchs.

Conversely, an unsettling decline has been observed at the Goleta Monarch Butterfly Grove at Ellwood Mesa. George Thomson, Goleta’s Parks and Open Spaces Manager, didn’t mince words in describing the winter’s count at Ellwood Mesa as “abysmal.” The adopted symbol of the City of Goleta, a stylized Western Monarch Butterfly, underscores the local connection to this threatened species.

According to the latest federal Species Status Assessment, there’s a sobering prediction that the Western Monarch butterfly faces a greater than 95 percent risk of extinction by the year 2080, if substantial conservation measures are not implemented. As the situation for monarchs becomes increasingly precarious, the collective response from wildlife agencies, conservation groups, and the public will be critical in shaping the future of this cherished butterfly in California and beyond.