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.
That migration is now in crisis. In the winter of 2018, and again in 2019, the western monarch overwintering population has reached the lowest level ever recorded—less than 1% of historic populations, and a dizzying 86% drop from the year prior. 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.