From November to March each year, you can be witness to one of the most spectacular natural phenomena in the forested mountains west of Mexico City: Monarch butterflies over-wintering in Mexico.
The very special Methuselah generations of butterflies migrate each year, leaving the colder northern climes of the U.S. and Canada to take winter refuge and breed in Mexico.
These migrating Monarch butterflies travel in colonies of about 20 million insects and will travel between 80-120 nautical miles per day, depending on the wind and other weather conditions. The butterflies take advantage of ascending warm-air currents, gliding in the thrust they provide, 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.
The butterflies usually start arriving in early November, and between mid-late November and the end March, it’s possible to visit one of the sanctuaries open to visitors and witness these remarkable insects in their natural habitat.
The Monarch Butterflies settle in the Oyamel fir tree forests which are situated west of Mexico City; along the eastern perimeter of the Mexican state of Michoacán, also bordering the State of Mexico. Once here, the butterflies cluster on the tree trunks and remain in the region 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 in the evening.
Peak viewing season is between mid-January and the end of March. Before the mid-January, the air temperature on the mountain is colder and the butterflies don’t flutter as much.
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, while still allowing visitors to witness these remarkable insects amidst some of Mexico’s most breath-taking landscapes.
You can learn more about these butterflies, their migration, their breeding cycle, and their journey back north on our detailed travel guide to Monarch Butterflies in Mexico. Watch the PBS video below for a glimpse of this extraordinary experience.
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