The Monarch Butterfly is native to the North American tropics.
Milkweed plants provide an essential food source for their caterpillars. The milkweed allow the butterflies to assimilate and store it in the cells of its outer skin, which in turn provides the butterfly with a powerful defense ‘shield’ against predators and assists the insects in their 3,000 mile journey south, for winter, to the mountains west of Mexico City.
Monarch butterfly migration occurs through travel in colonies of about 20 million insects and will travel between 80-120 nautical miles per day, depending on the wind and weather conditions. The butterflies take advantage of warm-air currents, needing only to flap their wings when the air current diminishes a little or when they change their flight path. This technique uses their energy efficiently, and physically enables them to undertake the long journey.
By around mid-November each year, the Monarch butterflies will begin their travel to Mexico. They settle in the fir tree forests situated in the eastern part of Michoacan, also bordering the state of Mexico, in the forested mountains west of Mexico City. They cluster on the tree trunks and remain in the area for the winter. As the sun heats the day, some of the butterflies will flutter in the forests and return to the tree trunks when the air cools.
Not far from Valle de Bravo, you can visit sanctuaries independently or you can go as part of an organized Monarch butterfly tour. Most guided tours visit the El Rosario or Sierra Chincua reserves. The Mexican government has set up a number of protected sanctuaries within a biosphere reserve to ensure that the important habitats required by the Monarch Butterflies are protected and preserved, similarly on the level of protection some rare Mexican animals are receiving today, while still allowing visitors to witness these remarkable insects and enjoy some of Mexico’s most breath-taking landscapes. The Monarch Butterfly Biosphere Reserve covers an area of over 350 square miles and has been recognized by UNESCO as a World Heritage Site since 2008.