From November to March each year, one of the most spectacular natural phenomena can be observed 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 US 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.
By mid November each year, the Monarch butterflies begin their arrival in Mexico. They settle in the oyamel fir tree forests which are situated in the eastern perimeter of the Mexican state of Michoacan, also bordering the state of Mexico, in the forested mountains west of Mexico City. 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.
Depending on the year, the butterflies may start arriving in late September or in October, and between November and March each year, it’s possible to visit one of the sanctuaries open to visitors and observe these remarkable insects in their natural habitat. 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 and enjoy some of Mexico’s most breath-taking landscapes.
You can visit one of the sanctuaries independently or you can request a custom trip to see the Monarch Butterflies.
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.