The annual Monarch butterfly migration from Eastern Canada to Mexico’s central highlands is one of nature’s greatest spectacles! Each year, as many as 60 million to one billion Monarch butterflies make this journey that spans more than 2,500 miles. They spend their winter hibernation clustered in small areas of the Reserva de la Biosfera Mariposa Monarca (Monarch Butterfly Biosphere Reserve), a protected area and nature preserve that covers more than 200-square-miles. They migrate south in October and make their winter homes in the tops of the trees, high in the mountains of the reserve. Once within the confines of the reserve, they then spend the next five months clustering together and covering the tree trunks and branches in a blanket of orange and black. Each of these clusters consists of thousands of butterflies. This clustering together allows them to conserve heat and survive the cool night time temperatures common to this high-altitude region.
The Monarch butterflies reproduce during the months of February and March, just before they begin they return to the north. During this time of year, nights in the western central highlands of Mexico are still chilly, but the warmth of the daytime sun prompts the clusters to break apart and the butterflies begin their mating rituals. They are most active during the mating season and it’s one of the best times of the year to visit the Monarch Butterfly Biosphere Reserve.
The Monarch Butterfly Biosphere Reserve is sectioned off into separate areas, several of which are open to the public from November through March. The most popular of these are the butterfly sanctuaries at El Rosario, Sierra Chincua, Cerro Pellon and Piedra Herrada. But, it is El Rosario which is the largest, the best known and the most visited area of the reserve. The Monarch butterfly observation point at El Rosario is situated at an elevation of 10,000 feet above sea level and reached via a steep climb up the hillside. Here, the butterflies make their home in the branches of more than 1,500 evergreen and oak trees that tower an impressive 100 feet above the forest floor.
Sierra Chincua is another heavily visited areas of the reserve, though less than El Rosario and offers the least strenuous hike of any of the sanctuaries. Sierra Chincua is located just a few miles north east of the town of Angangueo. There’s not much to see along the trails, and it’s only when you near the hilltop observation point that the butterflies begin to appear fluttering around overhead, and clustered on trees and branches. Every so often a strong gust of wind blows through the tree tops causing the butterflies to simultaneously burst into flight. The sound of their flying is like that of rain falling in the forest.
According to scientists, butterfly populations are declining, and this is a cause for concern, but for now these magnificent creatures are continuing to make their annual southern migration from Canada to the forests of western central Mexico, to the great delight of visitors!