CA Monarch Butterfly Population Drops 99%, Can Milkweed Save It?

SAN FRANCISCO, CA — Scientists believe that California's monarch butterfly population declined 99 percent from the 1980s to 2020 — an all-time low, according to the Xerces Society for Invertebrate Conservation.

To help restore habitats for these decadent butterflies, conservation group, River Partners, has partnered with the California Department of Fish and Wildlife to plant 595 acres of milkweed and other nectar-rich plants along the state's rivers and streams from Sacramento to San Diego.

"The collapse of the migratory monarch population has been steep and rapid," CDFW officials wrote on their website. "An effective response requires participation from the public and land managers across the state to help kick-start recovery efforts."

These plants provide important breeding hotspots for these orange-and-black butterflies, where they commonly lay their eggs. Caterpillars also feed on milkweed.

Each winter, these butterflies head south from the Pacific Northwest to California. But this year, researchers said an annual winter count recorded less than 2,000 monarch butterflies.

And fewer than 2,000 individual butterflies seek shelter in California's coastal groves, CDFW said.

"There couldn’t be a more critical time to be doing this," said restoration biologist Francis Ulep of River Partners.

Many essential milkweed habitats have reportedly been destroyed as housing development expanded in the Golden State for the past several decades. The use of pesticides and herbicides has also wreaked further havoc on these vital plants.

Climate change has also contributed to the massive decline in monarchs, according to CDFW.

Between the CDFW, the U.S. Fish and Wildlife Service, the Xerces Society and the California Department of Parks and Recreation — priority regions are being developed with multiple initiatives in motion to kickstart the resurgence of monarchs.

California residents who want to help lend a hand in restoring these iconic beauties can do the following:

• Include native flowering plants in your home garden.
• Plant native milkweed.
• Ensure the plants you purchase from nurseries are pesticide-free.
• Limit pesticide use.
• Become a community scientist by volunteering to collect data on monarchs and milkweed. Information for the period of February through April is especially needed.

"With so few monarchs left in California to jump-start this year’s breeding season, they need all help they can get. Efforts to improve monarch habitat in California this spring is more important than ever," a report from the Xerces Society says.

All monarch butterfly sightings can be reported to the Western Monarch Milkweed Mapper.

The Associated Press contributed to this report.