Monarch Butterfly Sanctuaries in Mexico
The Monarchs arrive at their Mexico wintering grounds in masses in the final days of October. Their arrival coincides with el Dia de los Muertos, or the Day of the Dead, a Mexican traditional holiday that honors the deceased. The indigenous people of Mexico believe the butterflies are the returning souls of children and warriors.
Monarch butterflies cannot survive a long cold winter. They spend the summer months in the United States and Canada and the winter in roosting spots. The monarch’s migration is driven by seasonal changes. Day length and temperature changes influence the movement of the Monarch. Every year hundreds of millions of monarch butterflies undertake a great journey of up to 3000 miles in their annual migration from Canada and the United States to the central Mexico’s Oyamel fir forest for the winter.
The Monarch Butterfly Biosphere Reserve was recognized by UNESCO as a World Heritage site in 2008. There are a few areas that are open to the public. Visiting the monarch butterfly reserves offers the visitor a chance to witness a wonder of nature. Being surrounded by thousands of fluttering butterflies and seeing them carpeting the forest floor and weighing down the branches of the trees is truly a remarkable experience.
The Monarch butterfly reserves in Mexico are open daily from mid-November through March. El Rosario Santuario de la Mariposa Monarca and Sierra Chincua Reserve Sierra Chincua Santuario de la Mariposa Monarca can be visited as a long day trip from Morelia.
There are many unanswered questions about this amazing migration phenomenon. How are they able to travel so far? How do they find the overwintering sites each year? Fat, stored in the abdomen, is a critical element of their survival for the winter. This fat not only fuels their flight of one to three thousand miles, but must last until the next spring when they begin the flight back north. As they migrate southwards, Monarchs stop to nectar, and they actually gain weight during the trip! Some researchers think that Monarchs conserve their “fuel” in flight by gliding on air currents as they travel south. Somehow they know their way, even though the butterflies returning to Mexico or California each fall are the great-great-grandchildren of the butterflies that left the previous spring. No one knows exactly how their homing system works
In March, the same butterflies that made the journey south will begin the return trip. The migrants fly to the southern U.S., where they mate and lay eggs. Their descendants will continue the migration north. In the northernmost part of the Monarch’s range, it may be the great grandchildren of the migrants that finish the trip.