every year, at the beginning of November, one of the most impressive natural spectacles in the world takes place in Michoacán, Mexico. Hundreds of millions of migrating monarch butterflies settle in the forested massifs of the country’s Monarch Butterfly Biosphere Reserve, roughly 100 kilometers west of Mexico City. Having flown south for eight months, beginning their journey in the northern United States or southern Canada, they hibernate here for the winter before mating in the spring.
After flying for more than 4,000 kilometers, the butterflies land in the oyamel fir trees of the Ejido el Rosario region, where for weeks they congregate, protecting themselves from the wind and the cold