It’s one of Mother Nature’s most beautiful and inspiring mysteries: the migration of the monarch butterfly from North America to the Michoacán forest in central Mexico and back. It’s been happening for thousands of years, and it will, no doubt, continue for thousands more. But will we ever truly understand why?
Ten thousand feet up a slope in the Sierra Nevada mountains of central Mexico, the dusty trail of the El Rosario butterfly sanctuary abruptly changes to cement steps. Above our heads, bright orange flickers dart in and out of the trees. Each autumn, millions of Monarch butterflies migrate from North America to this dormant peak, swarming across highways, riding high-altitude currents, stopping only to rest in trees along the way.
After hibernating in the Michoacan forest, they awake in the spring, mate, and begin the journey back to the U.S. and Canada to lay their eggs. It’s an incredible feat of nature. Some will travel over 5,000 miles. And they’ve been doing this every year, for thousands of years.
But the spectacular journey is not without its pitfalls. “Ohh, no.” Our guide Alfredo stops, bends down and gently picks up a wounded Mariposa Monarca from the trail. It’s a male, almost dead, feebly moving its wings and legs. “See?” he indicates. “The stomach is missing.”
The Monarch is highly toxic to the tastebuds, Alfredo explains. Even a cow can die if it eats one. The only part not poisonous is the butterfly’s stomach. Unfortunately for the Monarch, its predators have learned this. Local birds, in particular orioles and grosbeaks, will attack the butterfly in mid-air, suck out the organs, and let it fall to the forest floor, where the insect wiggles helplessly for a few minutes before it dies. A horrendous fate for such a cute creature. But nature is not always pretty.
We humans might prefer the beaches of Puerto Vallarta or Ixtapa for our winter vacation. Monarch butterflies are much more discerning. They congregate in colonies only atop 12 specific volcanic peaks in central Mexico’s Trans-Mexican Volcanic Belt, a 75-mile wide protected reserve.
While this region produces 80% of the world’s avocados, civic leaders also heartily embrace their other natural resource. The Morelia school soccer team is named the Monarchs. The mining town of Angangueo hosts an annual Monarch Festival each spring, and road signs throughout Ocampo boast cute butterfly icons. The footpath beginning at the El Rosario parking lot up is lined with butterfly trinket vendors, and women cooking over open flames.
We continue our hike up the trail, and Alfredo says out of the 12 sanctuaries, two are in this region. El Rosario is the most visitor-friendly, the other you have to enter on horseback. He’s been giving Monarch tours for six years, six to seven days a week. Approximately 200 million butterflies hibernate in Michoacan each winter, he says, with 20 million coming here to El Rosario.
In the U.S.and Canada, Monarchs only live 6 to 8 weeks, from egg to caterpillar to butterfly. Here in Michoacan, the migrating generations live up to 9 months, most of that in blissful slumber.
The colonies awaken and by February they’ve departed north to lay their eggs in warmer conditions. By March the first generation eggs are laid in the southern U.S. In April the Midwest will see a second generation of eggs, and a third generation is born in the Great Lakes and Northeast U.S. around July and August.
According to Alfredo, it takes three generations to reach the U.S., about five to get to Canada. The migration season roughly follows the annual growth cycle of the milkweed plant, a favorite food of the Monarchs.
As the weather gets colder in September, the newest butterflies start moving south towards Mexico, roosting overnight in trees along the way. Swarms can be spotted in the Midwest states of Oklahoma, Kansas, and Iowa around early October, and then they cross into Mexico a week or so later. This hardy final generation doesn’t breed or die along the way, they stay the course and arrive at the volcanic peaks of Michoacan each November to tuck in for the winter.
Monarchs east of the Rocky Mountains follow this North America-to-Mexico migration route. Butterflies west of the Rockies funnel down to southern California for their hibernation months.
The tiny insects are astonishing travelers. They can do 80 miles a day, at an average of 12 miles per hour, and if the winds are right, they cruise at an altitude of two miles. They travel during the day, living off their stored fat, and stop to eat only if there are flowers. If there is fog or clouds, they stay put, preferring to move only during bright sunny weather.
But why do they come to Michoacan? For centuries, locals believed the annual butterfly swarms were some sort of plague, and would kill as many as they could. The more superstitious still believe Monarchs come to this area to visit their dead ancestors.
Another popular rumor circulates that a magnetic field attracts the Monarchs to these mountains. Tantalizing, but not true. The real reason is more obvious, says Alfredo. “Butterflies look for protection, that’s why they come here. There’s high elevation, they are protected by the tall trees’ branches, there are flowers, and water. So they don’t waste energy.”
Local indigenous tribes have always known about the Mariposa Monarcas, but scientists in North America still had no idea where the butterflies wintered. Each year, the swarms just seemed to disappear south across the Rio Grande River. The mystery was finally solved in 1975, thanks to an underwear executive and a 12-year-old boy from Texas.
Volunteers had tagged thousands of butterflies under the direction of Canadian entomologist Fred Urquhart. Thirty years of research indicated that migrating Monarchs hibernated somewhere in Mexico, but Urquhart’s team was unsure of the location.
Ken Brugger, an American working in Mexico as chief engineer for Jockey underwear, had heard of Urquhart’s efforts. Being somewhat of an amateur naturalist, he offered to help, and began his own inquiries to the locals. On January 2, 1975, Brugger and his wife scaled the slopes of a Michoacan summit named Cerro Pelon, and discovered millions of hibernating butterflies clinging to the trees.
The Bruggers eagerly picked through the colony for Monarchs that might have been tagged in North America, thus establishing conclusively the exact migration route. They were having little luck, until they came upon one butterfly which stood out from the rest. It was significantly larger. And it had a tag. With a phone number.
For a few years, 12-year-old John McLusky had been tagging butterflies in Fredericksburg, in south-central Texas. He had read about the migrations, printed up his own tags, and did it all himself.
“I didn’t know there were any professionals doing it,” says McLusky, now a chemistry professor at Texas Lutheran University. “I was hoping that someone would find them. I didn’t really know I was contributing to science.
“Ken Brugger called my home from Mexico,” he recalls. “They were very excited. They found what they’d been looking for all these years.”
Alfredo and I pass through an open meadow ringed by forest, and Monarchs circle lazily above us, the sun casting their shadows on the ground. The trail turns back into forest, and he says we should be quiet. Monarchs are totally deaf, but they can apparently detect light and movement, and have a terrific sense of smell.
It’s true. Dozens of butterflies cling to bushes, then quickly flutter away just out of our reach. The treetop canopy up above bustles with tiny flashes of orange.
Alfredo opens a wooden fence and takes us off the trail. We walk a bit further, and then he stops and points. Giant pod-like clumps dangle from trees, pulsating slightly with movement. They look like grayish alien larvae from a horror film, but in fact it’s thousands and thousands of Monarchs all slumbering together, weighing down the branches, which look as though they are about to snap off. This is the Mother Lode, the starting point of nature’s most mysterious migration.
The grey color comes from the undersides of the wings, and blends in easily with the forest shade. Alfredo whispers that throughout the winter they will rotate sleeping positions, so that the ones on the outside don’t freeze to death.
Monarchs prefer pine and oyamel trees for their winter hotel, and for some reason extend their colonies out in a straight line through the forest. Each year, the location moves slightly, Alfredo says maybe 100 meters or so, because of the dust that humans kick up.
The sky comes alive as the butterflies respond to the late morning sun. Once they wake up, they fall to the ground and start flapping their wings to warm up. You have to watch where you step, because the ground is carpeted with groggy butterflies flopping around. Once they’re fully alert, they start mating furiously.
I step into a pocket of bright sunlight, and the sensation feels like wandering into the midst of a locust attack. Butterflies attach themselves to my head, pantleg, shoe, shoulder, back — at one point I count over 20 Monarchs perched somewhere on my body, curiously checking me out. I hear Alfredo say, “Look,” and turn around. One is affixed to his lips.
Perhaps it’s the 10,000 feet altitude that’s making me light-headed, but being covered in little butterflies seems like we’re all part of a spectacular Disney movie where everything is going to be okay. At any moment Miley Cyrus is going to step from behind a tree and start singing “Zip-a-Dee-Doo-Dah.” There’s no noise at all except the woosh of tiny wings. It’s a soothing, dreamlike celebration of insect life – a combination hotel, breeding ground and cemetery.
I feel badly for John McLusky back in Texas. Of the three men responsible for discovering and verifying this amazing migration, he’s the only one still alive. And he’s never actually been here to see it himself.
Alfredo and I head back down the trail, and come upon a group of butterflies clustered on the ground, at a spring-fed rivulet. “They’re drinking water,” he whispers. Indeed, the Monarchs are guzzling like thirsty horses on a trail ride.
Alfredo describes a very moving moment in his life. One day while giving a tour, he saw a Monarch in a water puddle that appeared to be drowning. He gently picked it up and saw it was a female, she was weak and freezing. He held it in his hand to warm it up, and fed it by hand, squeezing nectar from a flower into its mouth.
“She could smell it,” he remembers. “They drink very fast.” The butterfly guzzled the contents of four flowers, then regained its strength and flitted away.
Alfredo smiles. “I never thought I was gonna be able to do that.”
Butterfly festivals occur in North America throughout the migration season, depending on location. Michoacan sightings are best during the spring season, when the region hosts a month-long Monarch Festival. Visitor info available at www.michoacan-travel.com (English) or www.michoacan.gob.mx (Spanish).
Jack Boulware contributes frequently to American Way. He was assisted for this story by an unknown butterfly who clung to his notepad for a good deal of the day.
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c/o Mitzi Arreola
Michoacan tourism department
011 52 (443) 317 80 52 Ext. 140
Michoacan.gob.mx – website of the region with info about Monarch Festival (in Spanish)
Biosphere reserve UNESCO site
lots of facts:
good first person account: