This season, the monarch colonies in the Reserva de la Biosfera Mariposa Monarca increased by 64%, marking the second consecutive year of recovery. At the heart of this return is the "Methuselah" generation—butterflies that live eight months rather than weeks, traveling four thousand kilometers from the north to settle in these specific Mexican peaks. In the colony of El Rosario, the largest recorded this year, the butterflies blanketed 1.62 hectares of forest, their bodies huddling together to conserve lipids in the thin, cold air.
Alicia Bárcena, overseeing the national conservation efforts, noted that the recovery was aided by a wetter summer in the north, providing the necessary nectar for the long journey. Yet the presence of these insects is not merely a matter of weather. It is the result of a deliberate choice made by the local communities who serve as the primary guardians of the land. Since 2008, illegal logging in the reserve’s core zone has been virtually eradicated, a feat of collective discipline that has preserved the microclimate these fragile travelers require to survive the winter.
The significance of these forests extends beyond the migration itself. María José Villanueva of WWF México emphasizes that the oyamel trees act as a vital sponge for the Sistema Cutzamala, the vast network providing drinking water to millions in the capital. The protection of the monarch is, by extension, the protection of a regional life-support system. While Pedro Álvarez Icaza credits the management of the biosphere for these results, he acknowledges that the butterflies remain vulnerable to the wider pressures of agricultural chemicals and changing climates outside the reserve’s borders.
As the final weekend of March approaches, the butterflies begin to stir, their internal sun compasses and antennae-clocks signaling the start of the flight back toward the north. They leave behind a forest that remains intact, held in trust by the people of the mountains who have chosen the long-term health of the trees over the immediate gains of the axe.