Every winter Mexico hosts a pair of extraordinary migrations. One, a round-trip of 3,000 miles, brings the gaudy monarch butterfly from the northern U.S. and southern Canada to its winter refuge in the south-central state of Michoacán. There shafts of morning sunlight pierce the forest as millions of silent visitors, each weighing less than a tenth of an ounce, cling to branches everywhere.

Seven hundred miles to the northwest, the 36-ton gray whale completes the southward leg of a journey from Alaska’s Bering and Chukchi seas to lagoons along the central shores of the Baja California peninsula. This pilgrimage, outbound and return, skirts 12,000 miles of coastline—a feat generally accepted as the longest known mammal migration.

Each of these passages has created its own minor travel industry; the layover sites for these vastly different creatures have become increasingly serious venues for responsible tourism. They offer naturalists and ecotravelers serene beauty, a window into the marvel of long-distance migrations, and a glimpse at the stresses that impact two of the planet’s magnificent and endangered citizens.

Kingdom of the Colorful
Monarch Butterfly Migration

One of the earth’s enduring mysteries is the invisible process that ushers millions of monarchs from throughout North America to the protective woodlands of Mexico’s 217-square-mile reserve called Santuario Mariposa Monarca. The flight south occurs from August through the end of October.

Because the journey exceeds the less-than-two-month life span of the “summer” generation of the butterfly, no individual completes more than part of the trek. The monarch’s chromosomal navigational codes are somehow passed to offspring that take up successive phases of the journey. The winter generation may live up to seven months, however, and reproduces only after it starts heading back north during the Mexican spring. Subsequent, short-lived generations then string together the rest of the journey.

The intricacies of this creature’s genetic profile may be lost on many tourists who make their own winter trip to Michoacán, but no matter. “It’s more a spiritual experience,” says Fern Malowitz, a psychologist in Jacksonville, Fla. She describes her first steep hike in the hills of the popular El Rosario sanctuary, one of the reserve’s three refuges. “We were in dense forest, every inch of foliage literally blanketed in bright orange, like a huge, living tapestry.” The butterflies hang in near-motionless hibernation during December and January.

Malowitz and her husband first visited this kingdom of the butterfly as clients of Colorado-based Natural Habitat Adventures, a provider of ecosensitive tours worldwide that also claims to be a carbon-neutral travel company. Natural Habitat’s catalogue describes the sensory impression of monarchs taking flight in February and March, when they set off again to the north: “As the sun warms their black and orange wings, the butterflies fill the air, illuminating the entire area.... Mexico’s sanctuaries are the only places in the world where you can actually hear butterflies’ wings beating.”

Although monarchs also flutter in Russia, the Azores, Sweden, New Zealand and elsewhere, they enjoy the greatest celebrity status in Mexico. Ancient Aztecs believed the butterflies were the souls of ancestors returning to the earth, cloaked as warriors. But the migration plays a serious role in the infrastructure of central Mexico, too. Numerous tour operators from the nearby village of Angangueo and cities such as Morelia and Mexico City provide excursions by truck, on foot and on horseback to the sanctuary’s three public areas: El Rosario, Sierra Chincua and Cerro Pelón.

The World Wildlife Fund and other conservation groups have expressed concern about the migration, with good reason. Although potential predators are few—the monarch is unpalatable and even poisonous to most would-be attackers—its fragile morphology and complicated life cycle make the insect vulnerable to fluctuations in temperature and food supply. A 2002 migration was ambushed by a winter storm that killed about 80 percent of its population. And needless to say, human habitation, development and commerce have added stress. Pesticides, ecology’s most prevalent ogres, decimate milkweed plants—the exclusive diet of monarch larvae—with predictable efficiency.

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