Monarch butterflies (Danaus plexippus) are perhaps the most well-known and beloved butterflies in North America. A ubiquitous sight in gardens, prairies, and natural areas from coast to coast, their arrival in northern states and Canadian provinces is viewed by many as a welcome sign of the change in seasons from spring to summer. Renowned for their long-distance seasonal migration and spectacular winter gatherings in Mexico and California, the monarch butterfly population has recently declined to dangerously low levels.
In the 1990s, hundreds of millions of monarchs made the epic flight each fall from the northern plains of the U.S. and Canada to sites in the oyamel fir forests in central Mexico, and more than millions of monarchs overwintered in forested groves on the California coast. Now, researchers and community scientists estimate that only a fraction of the population remains—a decline of approximately 80% has been seen in central Mexico and a decline of 99% has been seen in coastal California.
The Xerces Society, government agencies, partner organizations, and communities are working across the U.S. to protect and restore habitat for monarch butterflies across a broad array of landscapes, provide workshops and educational resources on monarch conservation, and conduct research—including facilitating community science projects like the Western Monarch Thanksgiving Count and the Western Monarch Milkweed Mapper.
A significant focus of our monarch conservation efforts focuses on western monarchs, which breed west of the Rocky Mountains and generally overwinter in coastal California. Western monarchs are less well-studied—yet they are at a greater risk of extinction as their eastern counterparts.
A set of rapid-response conservation actions that, if applied immediately, can help the western monarch population bounce back from its extremely low 2018–19 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.