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Mexico
The Monarch Butterfly Reserve
© WWF
Every fall, millions of Monarch butterflies (Danaus plexippus) embark on a two-month journey of approximately 2,796 miles from Canada and the United States to Mexico to hibernate. The travelers arrive in November and remain in colonies for five months in the Oyamel fir forests of central Mexico. Its North American migration is one of the world’s most impressive natural phenomena.
The forests where Monarchs hibernate are part of Mexico’s temperate ecosystems, found in the high mountains. Oyamel fir forest is a generic name that may be limited to firs or may also include cedar, pine and oak trees. These forests – thanks to microclimates (local environmental conditions) created by tree coverage and forest structure – provide perfect areas for the migratory Monarchs’ hibernation colonies. The region’s forests are home to a wide variety of flora and fauna typically found in temperate areas: amphibians and reptiles, over 130 bird species, rabbits, squirrels, tiny shrews, mice, opossums, armadillos and skunks.
The Monarch Butterfly Biosphere Reserve protects a mountainous area of more than 139,000 acres with oak, pine-oak, pine, and oyamel fir forests. The Reserve contains three core zones where productive activities are not permitted and two surrounding buffer zones where sustainable use is authorized. Low altitude areas have been drastically modified by agriculture and the creation of rural and urban population centers.
© WWF
Monarch butterflies are not endangered. What is at risk is the Monarchs’ marvelous migratory phenomenon. Most butterflies cluster on relatively few acres of forest within their Mexican hibernation areas. In such areas where they are so densely concentrated, the consequences of habitat loss or deterioration can be very serious.
The Reserve is also home to many groups of people. There are 93 community groups: 59 ejidos, 13 indigenous communities (Mazahua and Otomi ethnic groups), and 21 private properties. This social composition creates complex management and conservation challenges. Forest use and subsistence agriculture are critical for local community’s' survival. The region has a high level of migration due to unemployment and, at present, tourism is very important in the local and regional economy.
The main factors affecting the region’s forests include illegal logging, low-tech legal timber harvesting, agriculture, high impact tourism, unsustainable cattle management, and forest fires.
Other threats to the area include overexploitation and pollution of natural water springs, climate change, limited local capacity and limited local knowledge and valuation of the natural richness
The Monarch butterfly originated in the American tropics almost two million years ago. They belong to the group of insects known as Lepidoptera. Its wingspan is about 11 centimeters, across, and each butterfly weighs one to three quarters of a gram.
© WWF
Their distribution is determined by the presence of milkweeds, a vital food source for their caterpillars. Milkweed plants possess medicinal properties and are toxic for several species. Monarch butterflies, however, are capable of assimilating the toxins and storing them in their outer skin. Covered with this powerful chemical defense, they become highly protected from predators.
Each adult butterfly lives only about four to five weeks. But one of the many wonders of the Monarchs is the creation of a unique “Methuselah generation.” During the summer, the Monarchs give birth to a very special generation. Unlike their parents, grandparents, great-grandparents and great-great-grandparents, these newborn butterflies will survive seven or eight months. This generation performs the astounding feat of flying from Canada and the United States to Mexico.
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