The monarch is one of the best-known and most beloved butterflies in North America, occurring throughout a broad range of habitats across the U.S. and into southern Canada and central Mexico. Two populations migrate to overwintering sites each fall: monarchs east of the Rocky Mountains migrate primarily to high-elevation forests in central Mexico, while most monarchs west of the Rockies migrate to hundreds of smaller, wooded groves along the California coast. Yet, this once-common butterfly now faces an uncertain future, with annual monitoring of overwintering monarchs in central Mexico and along the California coast revealing significant population declines. In the 1990s, estimates of up to one billion monarchs made the epic flight each fall to Mexico, and more than one million monarchs overwintered in forested groves along the California coast. Now, researchers and community scientists estimate that only a fraction of the population remains. At the central Mexico overwintering sites, scientists have documented a decline of more than 80%, while in coastal California researchers have documented a decline of over 99.9% since the 1980s.
In the eastern U.S., researchers have identified loss of milkweed as one of the most significant factor contributing to the observed declines of monarchs; it is thought that loss and degradation of monarch breeding sites in the West has triggered similar declines. Other threats include climate change, pesticides such as neonicotinoids, loss and degradation of overwintering sites, parasites and disease. To better understand what threats monarchs and milkweeds face and where habitat has been lost, we must understand where are they exist in the western landscape. Enter the Western Monarch Milkweed Mapper! Data from the Mapper has informed a Habitat Suitability Model, which along with a recent isotopic study suggesting that the natal origin of overwintering monarchs in California come from across the West, have highlighted large key breeding areas; however, more data is needed in order to improve conservation and restoration work on the ground.
Conservation at Work
The Xerces Society and our partners are working to protect and manage the habitats that support all life stages of the monarch’s life cycle. We work at local, state, national, and international levels to promote monarch conservation efforts. In the West, this includes holding workshops for land managers, training biologists and volunteers to conduct surveys for milkweed breeding habitat, developing community science programs and tools to better address conservation issues specific to western monarchs, and restoring habitat with farmers, ranchers, and other land managers. Learn more on our Monarch page.
Western Monarch Call to Action
This Western Monarch Call to Action, led by the Xerces Society for Invertebrate Conservation, aims to provide a set of rapid-response conservation actions that, if applied immediately, can help the western monarch population bounce back from its critically low overwintering size. We recognize and support longer-term recovery efforts in place for western monarchs such as the Western Association of Fish & Wildlife Agencies (WAFWA) plan and Monarch Joint Venture (MJV) implementation plan. The goal of this call to action, however, 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.
The five key steps to recovering the western monarch population in the short term are:
1. Protect and manage California overwintering sites
2. Restore breeding and migratory habitat in California
3. Protect monarchs and their habitat from pesticides
4. Protect, manage, and restore summer breeding and fall migration monarch habitat outside of California
5. Answer key research questions about how to best aid western monarch recovery
Read our overarching recommendations—which apply to everyone from land managers to individuals:
Click here to download the Call to Action as a PDF. You can also jump to actions that individuals can take to support western monarchs.
How Can I Help?
Are you interested in supporting monarch conservation? There are a number of ways you can contribute, too!
- Take photos of monarchs and milkweeds in your area and submit your sightings to the Western Monarch Milkweed Mapper.
- Identify existing monarch habitat (which may include milkweed host plants, nectar plants, water sources, or roosting trees) and protect it!
- In areas where milkweed and nectar plants have been lost, consider creating or restoring habitat. Monarchs need nectar-rich flowers as adults and milkweeds for their young. Find monarch nectar plant lists and milkweed seeds for your region.
- Join the Bring Back the Pollinators Campaign and sign the Pollinator Protection Pledge!
- Support local and organic agriculture. Many insecticides and herbicides can be harmful to monarchs and milkweeds.
- Spread the word! Let your friends and family know you are contributing to monarch conservation and encourage them to participate too!
- Want to contribute to more community science projects? Check out some of the other projects occurring all over the country.