Flight of the Monarchs

It’s a cloudy February morning high in the mountains of central Mexico. A group of travelers stand still, staring up at fir trees. They squint and look through binoculars.

“Where?” someone whispers. “I don’t see anything.”

The tree branches sag, heavy with clumps of dead leaves. 

Or so it seems. Then the sun shines—and the secret is revealed.

The “leaves” are millions of sleeping monarch butterflies. Warmed by the sun, the insects flutter to life. The beating of their wings sounds like soft rainfall. 

Suddenly, a blizzard of orange swirls through the forest. The butterflies land on people’s arms, backpacks—even their heads! One monarch spreads its wings across a visitor’s cheek as if giving the gentlest of hugs. 

Every year, millions of monarchs in the northern U.S. and Canada fly south to Mexico to escape cold winter weather. Some travel nearly 3,000 miles to reach these protected forests in the Sierra Madre mountains, about 60 miles northwest of Mexico City. 

The monarchs’ journey is one of nature’s greatest migrations. But it could disappear, says biologist Eduardo Rendón Salinas of the World Wildlife Fund (WWF). 

Salinas has spent 30 years studying monarchs in Mexico. In that time, their numbers have fallen by about 70 percent. Loss of habitat and food sources, combined with climate change, has driven the decline.

“The monarchs are in real danger right now,” says Salinas. “They face so many threats.”

Can we save this iconic species before it’s too late?

It’s a February morning in the mountains 

of central Mexico. A group of travelers stand still. They stare up at fir trees. They squint. They look through binoculars.

“Where?” someone whispers. “I don’t see anything.”

The tree branches sag, heavy with clumps of dead leaves.

Or so it seems. Then the sun shines. And the secret is revealed. The “leaves” are millions of monarch butterflies. They were sleeping. But warmed by the sun, the insects flutter to life. 

Suddenly, the butterflies swirl around and land on people’s arms, backpacks—even their heads! One monarch spreads its wings across a visitor’s cheek as if giving a hug.

Every year, millions of monarchs in the northern U.S. and Canada leave to escape cold winter weather. They fly south to Mexico. Some travel nearly 3,000 miles. They reach these protected forests in the Sierra Madre mountains. That’s about 60 miles northwest of Mexico City.

The monarchs’ journey is one of nature’s greatest migrations. But it could disappear, says Eduardo Rendón Salinas. He’s a biologist with the World Wildlife Fund (WWF).

Salinas has studied monarchs in Mexico for 30 years. In that time, their numbers have fallen by about 70 percent. Loss of habitat, loss of food sources, and climate change have led to the decline.

“The monarchs are in real danger right now,” says Salinas. “They face so many threats.”

Can we save this iconic species before it’s too late?

Imagine that you’re a monarch butterfly. Your striking orange-and-black wings make you instantly recognizable—a celebrity of the insect world. Plus, your transformation from caterpillar to butterfly is one of the first things kids learn about in school. Maybe that’s why people always smile when you flutter past. 

Most monarchs live only two to six weeks. But you’re special. You belong to a monarch “super generation,” which are monarchs born in late summer. These monarchs live longer than others—around eight months—in order to make an incredible journey.

Your home is a patch of wildflowers in Pennsylvania. One day in September, you shiver. The air has turned cooler. This means you’ll have to head south to avoid freezing. 

When you take flight, you know exactly where to go—even though you’ve never been there before. It’s as if you hold a map in your mind. How? It’s a mystery. But scientists believe monarchs have been making this flight for thousands of years.

The sun’s movement across the sky acts as your compass. An internal clock in your antennae keeps you on schedule. And your wings—no wider than an iPhone—can carry you up to 100 miles a day. 

Along the way, you stop to sip nectar from flowers. As you move, you carry pollen from one flower to the next. That helps plants grow, and it’s part of your job as an important pollinator.

After flying for a couple of months, you reach the forests of Mexico. Finally! You huddle with other monarchs for warmth and fall asleep.

Imagine that you’re a monarch butterfly. You’re a celebrity of the insect world. Your orange-and-black wings make you instantly recognizable. And in school, kids learn how you transform from caterpillar to butterfly. 

Most monarchs live only two to six weeks. But you’re special. You belong to a monarch “super generation.” These are monarchs born in late summer. These monarchs live longer—around eight months—so they can make an incredible journey.

Your home is a patch of wildflowers in Pennsylvania. One day in September, you shiver. The air has turned cooler. So you head south to avoid freezing.

You know exactly where to go—even though you’ve never been there before. It’s as if you hold a map in your mind as you fly. How? It’s a mystery. But scientists believe monarchs have been making this flight for thousands of years.

The sun acts as your compass.An internal clock in your  antennae keeps you on schedule. Your tiny wings carry you up to 100 miles a day.

Along the way, you stop to sip nectar from flowers. You carry pollen from one flower to the next. That helps plants grow. It makes you an important pollinator.

After flying for a couple of months, you reach the forests of Mexico. Finally! You huddle with other monarchs for warmth and fall asleep.

In Mexico, the monarchs’ fall arrival holds deep meaning. The tiny travelers begin to appear around Día de los Muertos, the Day of the Dead. During that holiday, on November 1 and 2, families honor those who have died. Many believe the monarchs represent the souls of departed loved ones coming home for a visit.

The butterflies spend the winter resting. In the spring, they head back north. They don’t make it all the way back, though. As they travel, the monarchs breed. Their offspring—and the generations that follow—continue the trip north, almost like a monarch relay race.

By late summer, a new super generation has emerged. They’re the great-great-grandchildren of the monarchs that flew to Mexico the year before.

But this amazing migration may not continue much longer. Scientists estimate that about 300 million monarchs spent the winter in Mexico in 1994, when the WWF began tracking them. By 2025, the population had dropped by 70 percent, to roughly 66 million.* 

Annual monarch counts rise and fall with the weather. A bad storm, for instance, can wipe out millions. But scientists say the overall trend is clear: Monarch populations are in steep decline. 

The main reason is the loss of a plant called milkweed. Despite its name, milkweed is actually a wildflower. It’s critical to monarchs: They lay eggs only on milkweed leaves, and their caterpillars can’t eat anything else.

Milkweed once grew plentifully in North America. In the Midwestern U.S., which is an important breeding ground for monarchs, fields were full of the plant. But millions of acres of milkweed vanished as land was converted to farms and housing developments. Herbicides made the problem worse. People spray these chemicals to kill weeds, but milkweed dies too. 

This means that monarchs don’t have enough places to lay their eggs—and their caterpillars don’t have enough to eat.

In Mexico, the arrival of the monarchs holds deep meaning. They begin to appear around Día de los Muertos, the Day of the Dead. During that holiday, on November 1 and 2, families honor those who have died. Many believe the monarchs represent the souls of departed loved ones coming home for a visit.

The butterflies rest for the winter. In the spring, they head back north. However, they don’t make it all the way back. But as they travel, they stop to breed. Their offspring—and the generations that follow—continue the trip north. It’s almost like a monarch relay race.

By late summer, a new super generation has emerged. They’re the great-great-grandchildren of the monarchs that flew to Mexico the year before.

But this amazing migration may not continue much longer. In 1994, the WWF began tracking monarchs. Back then, 300 million monarchs spent the winter in Mexico. By 2025, it was about just 66 million. That’s a 70 percent drop.*

Annual monarch counts rise and fall. A bad storm, for example, can wipe out millions. But the overall trend is clear. Monarch populations are in steep decline.

The main reason is the loss of milkweed. It’s a wildflower, not a weed. It’s critical to monarchs. They lay eggs only on milkweed leaves. And their caterpillars eat only milkweeds.

Milkweed once grew plentifully in North America, especially the Midwest. That’s an important breeding ground for monarchs. But land was converted to farms and housing developments. Millions of acres of milkweed vanished. Herbicides made the problem worse. People spray these chemicals to kill weeds. But milkweed dies too.

So monarchs don’t have enough places to lay their eggs. And their caterpillars don’t have enough to eat.

^{_{*Most monarchs in North America congregate in Mexico each winter. To count them, scientists measure how much forest the butterflies cover. Researchers estimate that 1 acre of forest holds about 15 million butterflies.}}

^{_{*Most monarchs in North America congregate in Mexico each winter. To count them, scientists measure how much forest the butterflies cover. Researchers estimate that 1 acre of forest holds about 15 million butterflies.}}

The monarchs’ winter home in Mexico has also faced many threats. The butterflies depend on healthy forests there. The fir and pine trees act like umbrellas, blocking rain and wind to keep the insects warm. But for many years, people cut down these trees—either to sell the wood or to clear land for farming. In 1986, the Mexican government made the monarchs’ wintering grounds a protected area: the Monarch Butterfly Biosphere Reserve. Still, illegal logging continued. At its worst in the early 2000s, more than 1,000 acres of forest were lost in a single year.

Around that time, the WWF began working closely with nearby communities. The idea was simple: Help people earn money by protecting the forest instead of destroying it. 

Local people now patrol the land and guide the 120,000 tourists who come to see the monarchs yearly. Illegal logging has dropped sharply—down to only about 6 acres in 2024. Meanwhile, community nurseries raise 1 million trees each year to replant the forest.

At one nursery, Salinas proudly shows off rows of fir saplings that will someday shelter monarchs. “People can change, but we need to work with them,” he says. “Environmental education is the key.”

Today the Monarch Butterfly Biosphere Reserve spans 140,000 acres. Its largest sanctuary, in the small village of El Rosario, brims with life. Outside the entrance, vendors sell roasted pork and fresh tortillas. Small shops offer every monarch souvenir imaginable—from towels stitched with orange wings to sparkly butterfly stickers. 

The hope, Salinas says, is that both people and butterflies can thrive here.

The monarchs’ winter home in Mexico has also faced many threats. The butterflies depend on healthy forests there. The fir and pine trees act like umbrellas. They block rain and wind to keep the insects warm. But for many years, people cut down these trees. They sold the wood. Or they cleared land for farming. In 1986, the Mexican government protected the area as the Monarch Butterfly Biosphere Reserve. Still, illegal logging continued. At its worst in the early 2000s, more than 1,000 acres of forest were lost in a single year.

Around that time, the WWF began working closely with nearby communities. They helped people earn money by protecting the forest instead of destroying it.

Local people now patrol the land. They guide the 120,000 tourists who come to see the monarchs yearly. Illegal logging has dropped sharply. It was down to only about 6 acres in 2024. Meanwhile, community nurseries raise 1 million trees each year to replant the forest.

At one nursery, Salinas proudly shows off rows of fir saplings. They will someday shelter monarchs. “Environmental education is the key,” he says.

Today the Monarch Butterfly Biosphere Reserve spans 140,000 acres. Its largest sanctuary is in the small village of El Rosario. Outside the entrance, vendors sell roasted pork and fresh tortillas. Small shops sell butterfly stickers, towels stitched with orange wings, and other monarch souvenirs.

The hope, Salinas says, is that both people and butterflies can thrive here.