For Immediate Release
Media Contacts:
Ray Moranz, Pollinator Conservation Specialist, Xerces Society for Invertebrate Conservation, 405-334-6684, [email protected]
Scott Black, Executive Director, Xerces Society for Invertebrate Conservation, 503-449-3792, [email protected]
MEXICO CITY; March 17, 2026 – The amount of overwintering habitat occupied by monarch butterflies in central Mexico increased 64% from last year, according to the annual census released today by World Wildlife Fund-Mexico and partners. The butterflies were found covering an area of 7.24 acres, which means the eastern monarch population that migrates between Canada and Mexico each year showed an improvement from last winter’s area of 4.42 acres. The annual survey measures the area of forest in which monarch butterflies hibernate each winter, providing a reliable indicator of the eastern monarch’s population status.
“While an increase is great news, the numbers in Mexico are still well below historic norms,” said Scott Black, director of the Xerces Society for Invertebrate Conservation. “With the western monarch population that overwinters in California seeing the third worst year on record, we urgently need better protections for this beloved butterfly.”
In late November, the Xerces Society’s Western Monarch Count counted 12,260 monarchs overwintering in tree groves in coastal California, the third lowest number ever recorded and well below the millions of butterflies observed in the 1980s that scientists consider a stable population. Scientists emphasize that while annual fluctuations in monarch numbers draw attention, the real concern is long-term decline of monarchs and other butterflies driven by habitat loss, pesticides, and climate change.
The delicate butterflies are renowned for their extraordinary migration each year, completed over four generations between Mexico and Canada for the eastern monarch population, and between California and the western U.S. interior for the distinct western population.
Thanks to new ultralight transmitters, scientists are now able to tag and track the butterflies along their migratory routes, opening up new opportunities to understand their conservation needs.
The Xerces Society and partners deployed approximately 470 monarchs in the eastern and central U.S. with Blu+ transmitters in fall 2025. Out of this cohort of tagged monarchs that made it to the overwintering colonies in Mexico and spent the winter there, female monarch XSTI009 (where the X stands for Xerces) appears to be the first to make it back to the United States. She crossed the Rio Grande into Texas on Saturday afternoon, March 14, 2026. Incredibly, by 6PM the following day, she had flown to the eastern edge of metro Houston, a distance of 320 miles in just one day.
“With monarch butterfly populations this low, they’re at a much greater risk of extinction if they encounter catastrophic weather events like extreme drought in the Midwest or blizzards at the Mexican overwintering colonies,” says Dr. Ray Moranz, a pollinator conservation specialist with the Xerces Society. “We know what they need to recover – more pesticide-free, native milkweeds and nectar flowers along their migratory route, and protected overwintering sites. We need everyone across the U.S., Mexico and southern Canada to create that habitat in yards, communities and rural lands – and quickly, before it is too late.”
What you can do to help monarch butterflies
- Discover milkweed and nectar plants native to your region and plant a pollinator garden.
- Reduce your reliance on pesticides and make change in your community, nursery, home, farm, and other places in your community.
- Participate in the tri-national International Monarch Monitoring Blitz this summer. Report monarchs any time of year, in any country to iNaturalist or another monarch community science program.
- Find additional ways to help the eastern and western monarch populations, including protecting overwintering sites in California and restoring breeding habitat in key regions of the United States.
- Support the Xerces Society, a science-driven nonprofit working on solutions for monarchs and other butterflies.
View the eastern monarch overwintering reports
For more information regarding the reports, contact: Eduardo Rendón-Salinas, Director del Programa Ecosistemas Terrestres, WWF México, [email protected], +52 (715) 1535055 y 1535466.
Area of Forest Occupied by Monarch Butterfly during the Winter 2025 2026
2025 Monitoreo Mariposa Monarca en México 2025-2026