California State Parks Foundation is encouraging Californians to report sightings of western monarch butterflies during California Biodiversity Day, Sept. 5–13, to help scientists track the declining species.
The nonprofit said data collected through public observations will help researchers understand where monarchs are throughout the year and support the upcoming 30th annual Western Monarch Count.
Western monarch populations have fallen dramatically in recent decades due to climate change, habitat loss, pesticides and disease. According to the most recent Western Monarch Count, the peak overwintering population was 12,260 butterflies, the third-lowest total recorded since monitoring began in 1997. A federal Species Status Assessment predicts a more than 95% chance of extinction for western monarchs by 2080.
"The western monarch butterfly is among the most beloved species in our state," Randy Widera, director of programs for California State Parks Foundation, said in a statement. "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.”
Residents can participate by downloading the free iNaturalist app, photographing a monarch butterfly or caterpillar, and uploading the observation.
According to the California State Parks Foundation, state parks provide critical habitat for western monarchs. An analysis of 26 years of population data found California state parks have hosted at least 20% of overwintering monarchs, with some years exceeding 50%.
During the 2024-25 overwintering season, Lighthouse Field State Beach, Natural Bridges State Beach and Pismo State Beach were among the top overwintering sites for western monarch butterflies, the foundation said.
