For Immediate Release, May 24, 2022
Scott Hoffman Black, Executive Director, the Xerces Society, (503) 449-3792, [email protected]
Portland, Ore.; Tuesday, May 24, 2022 -- The World Wildlife Fund Mexico has just released results of the annual survey of monarch butterflies overwintering in central Mexico. The butterflies occupied an estimated 2.835 hectares of forest during the winter of 2021–22. This represents an increase of approximately 35% compared to the previous winter (2020-21), when monarchs occupied 2.1 hectares.
The Mexico count follows the release of the Xerces Society's Western Monarch Thanksgiving Count that tallied 247,237 monarch butterflies observed across the West, an over 100-fold increase from the previous year’s total of less than 2,000 monarchs and the highest total since 2016.
While this year’s numbers from Mexico and the western U.S. are steps in the right direction, they still indicate a severe population decline in both the eastern and western population over recent decades, and with a long way to go to recover this species. Western monarchs have declined by more than 95% since the 1980s, while the eastern population has declined by over 70% in the last three decades.
In the 1990s, scientists estimated 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 north of Mexico City. Surveys in 1996 and 1997 estimated that over 18 hectares were occupied. Scientists estimate that at least 6 hectares are necessary to sustain the eastern population, meaning the current 2.8 hectares is still well below what is needed for recovery.
“This is great news and gives us some breathing room as we work to recover monarch numbers,” said Scott Hoffman Black, executive director of the Xerces Society for Invertebrate Conservation. “But there is still a long way to go to ensure that my grandchildren will be able to see monarchs every summer.”
Monarch butterflies (Danaus plexippus) of North America are renowned for their long-distance seasonal migration and spectacular winter gatherings in Mexico and California. Most monarchs east of the Rocky Mountains migrate to sites in the oyamel fir forests north of Mexico City to spend the winter. Many monarchs west of the continental divide overwinter along the California coast, but research has demonstrated that some western monarchs also go to Mexico to spend the winter.
Federal and state agencies and many nonprofit organizations are working to protect and restore habitat for monarch butterflies. The Xerces Society has been leading efforts to implement habitat projects in all landscapes including farms, roadsides, wildlands, and urban and suburban areas across the flyway and breeding areas for both the eastern and western populations.
Many unresolved challenges exist to fully recovering this species. Much of the monarch’s eastern habitat is now dominated by corn and soybeans that are genetically modified to allow large scale herbicide use that eliminates milkweed, the only plant monarch caterpillars are able to eat. Additionally, toxic insecticides are implicated in monarch decline, with research by the Xerces Society and University of Nevada at Reno documenting high levels of pesticide residue in milkweed collected from wildlands, farmlands, and in cities and towns. Logging at overwintering sites in Mexico also threatens monarchs, and destruction of overwintering sites for development is a factor along the California coast.
“All people can help monarchs by planting native milkweed and other native flowers and eliminating insecticide use,” said Hoffman Black. “If you can plant a home garden, if you can advocate for pollinator-friendly practices in your public parks, if you can restore monarch habitat on your farmland – then you can be part of the solution to save monarch butterflies from extinction.”
For More Information
Read more about Xerces’ Monarch Conservation Campaign, including efforts to conserve overwintering sites in California and restore breeding habitat in key regions of the United States at http://www.xerces.org/monarchs/.
To learn more about our work, please visit www.xerces.org.