But, just as often, they find themselves immersed in the rhythms of village life. In the monarch butterfly sanctuaries of central Mexico, the natural history story is linked in every way to the fortunes of the local people. The traveler's visit becomes as much a cultural as a wilderness adventure. But in winter, the monarchs disappear from the Eastern United States. They fly south, deep into Mexico, to mountain forests between the states of Mexico and Michoacan, where they may number 4 million per acre.
Butterflies cloak fir trunks and hang on boughs in clusters of tens of thousands.
Up to 250 million monarchs winter here. With folded wings, dusky surface out, the butterflies look almost drab. When they flex to soak up the sun, they flash their orange and black inner surfaces, and trim the firs with jewels. The usually quiet and stately grove fills with massed flight, a swirl of life, a whispering rain of sound. Monarchs dance past, for the most part avoiding human contact, but sometimes bestowing a kiss of wings or tiny feet, bumping against shoulders, perching on breast pockets.