Monarch butterfly population increases by 64%
Reports also show a decrease in forest loss within their winter habitat
© WWF-US / McDonald Mirabile
On the eve of spring, the eastern migratory monarch butterfly shows promising signs of recovery. Two new reports, both released by WWF-Mexico and its partners, estimate a 64% increase in species population and a significant decrease in forest degradation within their critical winter habitat, respectively.
Every year, a WWF-led survey measures the area of forest where monarchs establish their colonies to hibernate each winter, providing a scientifically robust indicator of their population status. This year, scientists found monarchs occupied 7.24 acres of forest compared to 4.42 acres the previous winter—indicating a 64% increase of monarchs during this period—according to Forest Area Occupied by Monarch Butterflies Colonies in Mexico During the 2025-2026 Hibernation Season.
© WWF-US / McDonald Mirabile
A second report measures and examines changes in the monarch’s critical winter habitat. Findings show that 6.30 acres of forest were degraded between February 2024 to February 2025—nearly three acres less than the degradation measured the previous year. Most of the recorded forest loss was due to illegal logging (4.58 acres), followed by forest fires (1.43 acres) and drought (.28 acres), according to Forest Degradation at the Core Zone of the Monarch Butterfly Reserve (2024-2025).
The eastern migratory monarch butterfly population has dramatically dropped in recent decades. Just 30 years ago, monarchs covered nearly 45 acres of forest in the winter. While population numbers fluctuate from year to year, there continues to be a long-term downward trend. Threats to migratory monarchs include not just forest degradation in Mexico, but the impacts of extreme weather in Canada, the US, and Mexico and the loss of breeding habitats in the US due to the use of herbicides and insecticides.
Today’s reports show that, despite challenges, conservation efforts are making a difference. WWF is working with the Mexican government, local communities, and other partners to promote strong forest management and sustainable tourism within Mexico’s Monarch Butterfly Reserve. WWF also supports tree nurseries that help restore the forest in the Reserve and provide economic livelihoods for communities living in the region. In the US, WWF is dedicated to reducing neonic pesticides, one of the leading drivers of monarch decline and restoring formerly plowed grasslands back to pollinator habitat in the Great Plains.
"Despite environmental challenges, today’s announcement shows promising signs of recovery for the migratory eastern monarch butterfly population,” says Maria Jose Villanueva, WWF-Mexico Director General. “These reports indicate conservation measures are going in the right direction. We also need to remain vigilant and not forget that this unique migration continues to face many challenges. WWF will continue to work together with local partners, the Mexican government, and especially with the local communities who are most critical to this success."
The monarch's remarkable migration and critical winter habitat
Every year eastern monarch butterflies travel up to 2,800 miles from Canada and the US to the forests they call their winter home, the Monarch Butterfly Biosphere Reserve in Mexico They cluster on Oyamel fir trees in one of nature’s most spectacular sights. Monarchs require a large and healthy forest mass to protect them from winter winds, rain, and nightly low temperatures
In addition to providing monarchs the right microclimate conditions for hibernation, the Reserve’s forests are one of the main freshwater contributors to the Cutzamala Hydrological System that provides water to more than 5 million people in Mexico City and its metropolitan area. These same forests boast incredible biodiversity, including 132 species of birds, 56 species of mammals, 432 species of vascular plants, and 211 species of fungi.
© McDonald Mirabelle / WWF-US
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