I am 11,000 feet up in Mexico’s Sierra de Angangueo mountains, and a monarch butterfly has just alighted on my shoulder. Around me, the air is thick with swirls of orange-and-black beauties, recently broken free from their jade-green chrysalises on the surrounding tree trunks. They sip water from forest streams, imitate blossoms on bushes, land on the clothing of their awe-struck human visitors.
No one knows why these enchanting, delicate creatures fly the length of North America—from Canada or the northern United States to Mexico or California—every year, but decreasing daylight and temperatures certainly play a part. Monarchs cannot tolerate freezing temperatures, which do occur in their northern homes, and their only food is milkweed, which does not grow in these southern sanctuaries. Yet they keep to their migratory schedule, perilous though it is (and getting more so—every year logging cuts into their winter habitat).
No one knows why these enchanting, delicate creatures fly the length of North America—from Canada or the northern United States to Mexico or California—every year, but decreasing daylight and temperatures certainly play a part.
For humans, a few sun-dappled hours in the world of butterflies is well worth the three-hour trek up the mountain path at El Rosario Monarch Sanctuary in the state of Michoacán. The authorities have worked to make the phenomenon accessible and protected: Signs in Spanish on the way up warn that even removing a dead butterfly is prohibited. Others ask for Silencio. The climb from the car park, through towering forests of oyamel firs, is paved most of the way with broad concrete steps, white rope guardrails on both sides, and resting places here and there. And at the top, seeing and being touched by clouds of brilliant, large, orange-and-black butterflies is a peak experience in anyone’s language.