Every autumn, millions of monarch butterflies fly up to 4,500 kilometers from Canada and the United States to the mountain forests of Michoacán and the State of Mexico. They spend the winter there, clustered tightly on fir trees, until spring pulls them north again.
New data from WWF-Mexico and Mexico’s national conservation authority Conanp show that in the 2025/2026 season, butterfly colonies covered 2.93 hectares of forest. The previous year, it was 1.79 hectares. That is an increase of 64 percent and the largest area since 2018.
The decline of monarch butterflies over recent decades has been dramatic: more than 80 percent since the 1990s. This season’s rise is a sign that conservation measures are working. But it is not a reason to relax. The population remains far below levels considered stable.
In the Biosphere Reserve, local communities have been working for years to stop illegal logging, reforest hillsides and build sustainable tourism. WWF-Mexico supports tree nurseries that restore the forest while providing income for families in the region. A second report shows that forest degradation in the core zone of the reserve has also declined significantly.
Nine colonies were counted this season: three in Michoacán, six in the State of Mexico. Five of them lie within the reserve, four outside it.
The road is long. But the butterflies fly it, and the people on the ground keep the forest ready.
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