In the north (the United States and Canada) these fragile creatures are spread out, but in Mexico almost all of them go to the top of the same mountain in Angangueo, Michoacan. The population is so dense that you can hear the sound of the flapping of their wings when the sun hits the trees and they take off to fly in the sun. Going flap; flap. And when the monarchs are in the trees the branches bend from their weight. Who could believe little butterflies bend a tree branch. They are numerous.
More information here Monarch butterfly
During the summer the monarch lives in the northern US and Canada. At the end of the summer it begins its’ southward migration and on November 1st punctually all the monarchs arrive in Michoacan. They spend the winter in Michoacan, Mexico and mate and in the spring return north. As these fragile creatures have a lifespan of only a few months the monarchs who came to Mexico from Canada are not the ones who return, but their offspring. So the monarch migrating to Canada in the spring never went there before. And likewise the monarch leaving Canada and the northern US to migrate to Mexico never went there before. Each trip is a new generation, but yet each new generation knows to return to this same mountain. So if they can find it, so can you.
In the morning you hire a pick-up truck to take you up the mountain and after a half hour bumpy ride over a dirt trail you climb for another half hour on foot to see this miracle of nature. Going up the mountain you pass small remote villages whose life is dedicated to the butterfly where almost everyone is engaged in the task of making monarch butterfly souvenirs. You can find monarch butterfly plates; napkin holders; pins; plates; picture frames; the people of the town are most grateful to the Canadian who discovered that the monarch migrates here in the winter. Thanks to him they have a thriving tourist industry. In its’ trip south the little butterfly travels about 70 miles per day; it travels over 1,800 miles in about 25 days. And it’s only a few inches long. It only flies during the day. During the night they eat. The descendants from last year’s trip feed on alkaloid plants commonly called swamp milkweed or cow’s tongue which are poisonous to other species. For the monarch this is a form of protection as if a bird would try to eat it the bird would die from an accelerating heart rate. Knowing this all the birds leave the colorful monarch alone.
Unlike birds or wildebees that also embark on epic migrations, these individual monarch butterflies will never return. They make the trip one way. Then a new generation goes back to Canada. How does each generation know the way? As the days get shorter and the temperatures drop down, monarch butterflies begin to abandon breeding and feeding territories in search of a safe place to spend the winter. For monarch butterflies, that overwintering ground is found high up on just a few mountains in central Mexico. Once there, the monarch butterflies huddle together by the millions on the branches of oyamel fir trees. The tree canopy and ecosystem in Mexico provides a blanket effect for the monarch butterflies, so the temperatures don’t go too high or too low. As adults, monarch butterflies visit countless numbers of wildflowers each year as they seek out nutrient-rich nectar. In doing so, the monarch butterflies transfer pollen from one plant to another and assist in those species’ reproduction.
The biosphere mariposa monarcha (monarch butterfly) is a World Heritage Site. A World Heritage site is an area which is selected by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as having cultural, historical, scientific or other form of important significance, and is legally protected by international treaties. The sites are judged important to the collective interests of humanity. So you’ll want to visit it. The monarch butterfly reserve extends from the mountainous forests of eastern Michoacán to western Mexico State around 100 km northwest of Mexico City. The reserve in Michoacán contains the highest elevations in the state, including peaks that reach 2,700 metres above sea level. That’s tall.
See more http://www.cancunsteve.com/monarch.htm with photos.
For a base while visiting this domain of the butterfly consider this hotel in nearby Morelia http://www.cancunsteve.com/guanajuato/mendoza.htm
In downtown Morelia one can dig the impressive Cathedral, where on every Saturday there is a sound and light show including some fireworks. Images are projected on the walls of the building. No butterfly images however. But it’s a lovely display.