Skip to main content
Monarchs cluster on pine branches, which are backed by blue sky. The butterflies with folded wings are more drab in color, appearing to be dead leaves at first glance. The butterflies with their wings spread display a vibrant orange hue.
(Photo: Xerces Society / Candace Fallon)

Since the 1980s, the Xerces Society has worked to protect monarch butterflies—including the western population of monarchs that overwinters in forested groves along the California coast. We help facilitate the Western Monarch Thanksgiving and New Year’s Counts, community science projects in which volunteers track the size of the monarch population at overwintering sites annually. The Western Monarch Thanksgiving Count has been running for over 20 years, and has not only provided a large dataset, but also helped the Xerces Society to sound the alarm in early 2019 when the western monarch overwintering population reached an all-time low of less than 1% of historic levels. In response to this situation, we developed the Western Monarch Call to Action, which includes provisions regarding the management of overwintering sites.

We have also used information derived from community science efforts, along with field surveys, to prioritize the top 50 overwintering sites most in need of protection and active restoration in our State of the Overwintering Sites, and have developed habitat management guidance for overwintering sites in California and site-specific management plans. With conservation partners, we are also on the ground, working to restore some of California’s most important monarch overwintering sites.