California’s Monarch Butterfly Numbers Continue to Plummet With One of the Lowest Tallies Ever

Western monarch butterflies have begun settling into their overwintering sites along the California coast, but early numbers show another troublingly low season. With the mid-season Western Monarch Count wrapping up this Sunday, scientists and volunteers have tallied about 8,000 monarchs—potentially the second- or third-lowest count ever recorded. Last year’s mid-season total reached 9,119.

Two sites in Santa Cruz County—Natural Bridges State Beach and Lighthouse Field State Beach—are once again the bright spots, each hosting over a thousand butterflies and open to public viewing. Elsewhere, numbers remain sparse: Pacific Grove Monarch Sanctuary has counted about 172 monarchs, Pismo State Beach is hosting 449, and Goleta Butterfly Grove has just 18.

Southern California and much of the Central Coast continue to see unusually low monarch activity.

Monarch populations naturally fluctuate, but this year’s low numbers likely stem from another warm, dry summer across the West combined with last year’s weak overwintering population. Meanwhile, early reports show eastern monarchs in Mexico are faring better this season—highlighting sharp regional differences in butterfly health.

Researchers from the Xerces Society and partner organizations are now tagging overwintering monarchs with ultralight BluMorpho radiotags to study their movement along the Central Coast. Anyone can track tagged butterflies in real time using the free Project Monarch App for iOS and Android.

Conservation groups emphasize that continued habitat restoration, data collection, and policy support are critical to helping western monarchs recover.