The Monarch Butterfly, in latin known as Danaus Plexippus, is native to the North American tropics. 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 their wintering grounds in Mexico. An adult wingspan will reach about 4.5 inches (11 centimeters) and weight one gram or less.
The Monarch Butterfly Biosphere Reserve was recognized by UNESCO as a World Heritage site in 2008. The protected area covers over 200 square miles. The 56,259 ha biosphere lies within rugged forested mountains about 100 km northwest of Mexico City.
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.
Autumn brings, millions, perhaps a billion, butterflies from wide areas of North America return to the site and cluster on small areas of the forest reserve, coloring its trees orange and literally bending their branches under their collective weight.
The butterflies begin arriving from mid November each year. January and February are the most popular months for visits, as it’s during this time that the butterfly population is at its peak In the spring, these butterflies begin an 8 month migration that takes them all the way to Eastern Canada and back, during which time four successive generations are born and die.
How they find their way back to their overwintering site remains a mystery. Visiting Mexico’s monarchs in their remote winter roosting sites is a rare nature experience.