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A monarch clings to a stalk with tufty yellow flowers, in a grassy, arid landscape.
(Photo: Xerces Society / Stephanie McKnight)

Historically, western monarchs have made a spectacular annual migration to overwinter in forested groves along the coast of California. Each spring, the butterflies fan out across the West to lay their eggs on milkweed and drink nectar from flowers in Arizona, California, Nevada, Oregon, Washington, Idaho, and Utah.

However, the western migration is in trouble. In recent years, the number of monarchs making the annual journey to coastal California has declined by >90%. In response to this, the Xerces Society has spearheaded the Western Monarch Call to Action, working in partnership with universities, government agencies, other organizations, and communities to stabilize and recover this imperiled population.

These actions are building upon the Xerces Society's decades of western monarch conservation work. Western populations have been less well-studied than their eastern counterparts, and have unique conservation needs. To that end, the Xerces Society conducts annual surveys of overwintering populations; assesses the status of overwintering sites; provides guidance for the management of breeding, migratory, and overwintering habitat; advises on habitat establishment and restoration; and researches the distribution of monarchs and milkweed in the West.


Western Monarch Call to Action

A set of rapid-response conservation actions that, if applied immediately, can help the western monarch population bounce back from its extremely low overwintering size. The goal of this call to action is to identify actions that can be implemented in the short-term, to avoid a total collapse of the western monarch migration and set the stage for longer-term efforts to have time to start making a difference.

Learn More

Managing Monarch Habitat in the West

The Xerces Society works extensively in the western United States to identify important habitat and assist land managers in adopting management practices that protect and support monarch populations.

Protecting Overwintering Sites in California

Overwintering sites across California are diverse—ranging from natural areas and public parks to state and private lands—and each have unique conservation needs.

Western Monarch Thanksgiving & New Year's Counts

Thanks to the efforts of dedicated volunteers, we now have over 20 years of data on monarch populations that overwinter along the California coast. Learn more about this annual effort and how you can get involved.


Tracking Monarchs and Milkweed in the West

Help us gather data across the West to further scientific understanding of monarch and milkweed distribution.