Southern Californians Urged to Report Monarch Butterfly Sightings

Southern California residents were encouraged Wednesday to report sightings of western monarch butterflies as part of an effort to help scientists track the species’ sharply declining population during California Biodiversity Day activities.

The California State Parks Foundation is asking residents to photograph monarch butterflies or caterpillars and upload the observations using the free iNaturalist app. California Biodiversity Day will be observed from Saturday through Sept. 13.

Information collected through the observations will help scientists determine where western monarchs are at different times of the year and contribute to the upcoming 30th annual Western Monarch Count.

Millions of western monarchs once returned to coastal California each year, but their population has fallen dramatically in recent decades because of factors including climate change, habitat loss, pesticides and disease, according to the foundation.

The most recent Western Monarch Count found a peak population of 12,260 butterflies, the third-lowest overwintering population recorded since tracking began in 1997.

Overwintering is the period when monarchs spend the winter in protected groves, where they conserve energy before mating and migrating north in the spring.

“The western monarch butterfly is among the most beloved species in our state,” Randy Widera, director of programs for the California State Parks Foundation, said in the announcement. “Californians can play a critical role in preserving our western monarch butterfly population by advocating for the protection of butterfly habitats and helping scientists track butterfly locations.”

Southern California state parks containing western monarch overwintering groves include Point Mugu and Leo Carrillo state parks, Doheny State Beach, San Clemente State Park and Torrey Pines State Natural Reserve.

State parks have hosted at least 20% of the western monarch population at overwintering sites during the 26 years analyzed by the foundation, and in some years the figure has exceeded 50%.