Overview
- The 29th annual Western Monarch Count tallied about 12,260 butterflies across 249–250 coastal overwintering sites during late November to early December 2025.
- This is the third-lowest total since tracking began in 1997, following lows of 9,119 in 2024 and a record 1,901 in 2020.
- Natural Bridges State Beach in Santa Cruz recorded the season’s highest site total with roughly 2,500 monarchs, while other well-known groves reported far smaller clusters.
- Long-term research estimates roughly a 10% annual decline since the 1980s, with scientists citing habitat loss, pesticide exposure, and climate change as primary drivers.
- Xerces and partners deployed about 100 ultralight radio tags in Santa Cruz to study overwintering movement as they press for protection of groves, highlight the loss of more than 60 documented sites, and urge Californians to avoid pesticides, plant native habitat, and support local conservation.