Nature's Secrets

Fall monarch migration is a yearly miracle

November 4, 2012 

Meg Lowman

If we can somehow retain places where we can always sense the mystery of the unknown, our lives will be richer.

Siguurd F. Olson, “Mystery and the Unknown”

We left the endless urban sprawl of Mexico City at 6 a.m., along bumpy roads in the mountainous state of Michoacán. It was hard to believe that only four hours from 20 million Mexicans is a winter haven for America’s entire population of monarch butterflies (Danaus plexippus).

Until recently, their mountain haven remained hidden to all but the local villagers. Even today, the sanctuary is so undeveloped that we drove right past the dirt track leading into it. Fortunately, upon turning around, our driver happened to notice two 6-year olds waving a tiny flag along the roadside. For five pesos, they eagerly hopped into our car and directed us along a dirt track into the forest. In the absence of the glitzy trappings of westernized tourism, we managed to locate the mariposa (Spanish for “butterfly”) sanctuary.

As we entered towering stands of oyamel trees, tiny specks of orange appeared overhead. Farther up the path, millions of monarchs clung to low branches amid a clearing. With wings folded, they are beautifully camouflaged in the evergreen canopies: The butterflies resembled brown foliage. But in flight, brilliant orange hues dominate the sky. As a biologist, I felt fortunate to observe the mariposas.

One of nature’s most incredible miracles is the migration of monarch butterflies, approximately 3,500 miles from Canada and United States to central Mexico. How can their fragile wings combat winds, thunderstorms, cold and heat to winter in the subtropics? Even more challenging, these tiny migrants face not only unfavorable weather but also bigger risks from human activities.

In the United States, tall buildings with nightlights skew the migratory compasses of butterflies (as well as birds); widespread clearing of lands and subsequent pesticide applications jeopardize butterfly rest stops along the journey. In Mexico, pollution and deforestation have reduced their 60 square miles of mountain sanctuary. Eight years ago, the wintering population slumped to 23 million. But recent reports indicate Mexico has virtually eliminated illegal logging of the wintering grounds, and local residents are now hired to patrol the sanctuary.

This is good news for butterfly-lovers!

Seeing the overwintering grounds of Monarch butterflies was in the top 10 of my lifelong “bucket list.” And knowing these fragile fliers now have a protected forest haven is a reason for hope in a world of otherwise dwindling natural resources.

Meg Lowman, an N.C. State University professor and forest canopy expert, directs the Nature Research Center, N.C. Museum of Natural Sciences. Online:

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