Out of Breath But Determined
It is a chilly February morning when I find myself in a forest outside of Mexico City. The air is thin at 9,800 feet (3000 meters), and as I start my hike into the fir forest, I quickly realize I'm in for a work-out. When you think of Mexico and envision white sand beaches, the last thing you expect to find this far south of the U.S. border is high, cold mountains with breathtaking alpine scenery. Yet, this is where you find one of nature's wonders.
What: Monarch Butterfly winter migration destination
Where: Biosphere Reserve, Michoacan State, Mexico
When: November to March
How: Car, RV
Tip: Prepare for high elevations in Mexico’s Biosphere. The Texas site is less strenuous.
Welcome to the Monarch Butterfly Biosphere Reserve!
About an hour into the hike, I notice a few butterflies flying between the tall trees. Severely out of breath, but determined, I continue climbing deeper into the dense forest. More and more butterflies appear out of nowhere until suddenly, I reach an area where the fir trees are seemingly alive. Millions of colorful butterflies hang in clusters on its branches, and thousands more have taken to the skies in a brilliant display of intense orange colors. Welcome to the Monarch Butterfly Biosphere Reserve! (A UNESCO world Heritage site)
NOTE: It happens sometimes. Apologies! We lead you astray. Monarch butterflies are notoriously difficult to distinguish from look-alikes, queen, and viceroy butterflies. One of our knowledgeable readers pointed out the identification error. We are humbly correcting our mistakes. See the end of the article for a monarch comparison chart. Many thanks to Carol Pasternak, The Monarch Butterfly Crusader. If (when) any of you catch a mistake, please speak up! We welcome your help.
Introducing, DANAUS PLEXIPPUS PLEXIPPUS
Monarch butterflies live around the world. Yet there are one subspecies of monarchs; the Danaus plexippus plexippus; that performs a miraculous migration every year. Unlike other North American butterfly species that can brave winter temperatures, these monarchs die when it gets too cold.
So what have they come up with?
The Amazing Flight of the Monarch Butterfly
At the first sign of winter, this monarch butterfly subspecies begin the 2,500 miles (or 4.000 kilometers) migration to a warmer climate. Come spring, they begin the return trip.
The butterflies, weighing only .25 to .75 gram (.009 - .03 ounce) use air currents to accomplish this great distance. On a typical day, they can travel around 75 miles. In case you are wondering why they don't simply live in Mexico year-round? The lack of a year-round food source doesn't allow this, so they are forced to take on this migration every fall and spring.
The Miraculous Migration
The distance of this migration may not sound astonishing to you; after all, many North American birds take on journeys of epic proportions annually. However, unlike birds, the individual monarchs that start the migration are not the same ones that return. In fact, the monarchs that finish the return trip and reach the summer grounds are the great-great-grandchildren of the ones who headed south the past winter!
Where They Go Depends On Where They Begin
The Great American Migration of the monarch butterfly starts around October. Monarchs that live west of the Rocky Mountains head south into California while monarchs that live east go to Mexico: a logical choice as many humans follow their example when winter arrives in the U.S. or Canada. How do they know where to go? After all, these individual butterflies have never made the trip before. That is part of the wonder.
Somehow, millions of monarch butterflies find their way from the northern U.S. or Canada to a small region in Mexico. Scientists have not yet been able to pinpoint how they do it. One theory is that the monarchs have a built-in compass allowing them to sense true north.
Another theorizes that they migrate to follow their food source, even when the food source is so far away they can hardly see or smell it. Whatever the reason, it's an awe-inspiring feat: these delicate insects somehow manage to fly months on end across multiple generations and across thousands of miles of landscape to arrive at their destination without getting lost.
Generation "S" the Super Monarchs
The monarchs that head south in winter make the entire journey to Mexico in one generation. These south-heading monarchs can live up to eight months and accomplish what it takes three or four generations to achieve on the trip back north: talk about a super-generation!
Monarchs that live east of the Rockies migrate south to Mexico. But not just anywhere in Mexico: they don't travel south solely for the warmer temperatures and settle on Mexico's sunny beaches. They all go to the same area near Mexico City, where they find mountains covered in oyamel fir forests. Recognizing the importance of this specific area for the monarch species, Mexico created the Monarch Butterfly Biosphere Reserve in 1986 to offer protection to these monarch colonies.
The Perfect High Elevation Microclimate
Here, at an elevation ranging from 8,000 to 12,000 feet (or 2.400 to 3.600 meters), the monarchs find the ideal microclimate. "The tree canopy and ecosystem provide a blanket effect for the monarchs, so the temperatures don't go too high or too low," says Pablo Jaramillo-Lopez, a research scientist at the National Autonomous University of Mexico. If the temperature drops too low, the monarchs use their limited fat reserves to stay alive, and the stable humidity allows the monarchs to save their energy by assuring they don't dry out.
The monarchs cluster together in groups of tens of thousands: this allows them to stay warm and conserve energy. Sometimes tree branches have been known to break under the combined weight of a cluster. Hard to imagine since one butterfly weighs less than a gram.
And, even in a forest of this size, the monarchs somehow manage to use the very same trees every year. Just another part of the wonder considering that the butterflies that arrive in a given winter aren't the same ones that were there last year!
DANGER. Avocados and Monarchs
Because they congregate in just a few locations during the winter, monarch butterflies are vulnerable to harsh weather and to human activities that impact their habitat in these select places. One example is illegal logging. Another example is caused by the growing demand for Mexican avocados. Avocados happen to grow in similar climates as the monarchs' preferred forests, and people who live near the Biosphere Reserve are increasingly replacing the forests with avocado plantations.
The Milkweed Problem
Also, along their migration paths, they are vulnerable to cold temperatures and human interference. The monarchs heavily rely on milkweed and nectar as their food source. Farmlands in the U.S. are increasingly sprayed with herbicides that kill milkweed. This is a problem for the monarchs, especially in southern states like Texas.
As the monarchs head north from Mexico during springtime, they lay eggs on the milkweed plants in Texas' warmer climate. Once the eggs hatch, the monarch larvae rely solely on milkweed before transforming into an adult butterfly. And, after taking to the skies as an adult butterfly, they continue heading north for about 6 weeks before - hopefully – finding another patch of milkweed, laying eggs, dying and leaving the successive generation to continue the journey north.
Is Monarch Butterfly An Endangered Species?
The subspecies that perform the North American migration is increasingly under threat due to the factors described above. It is estimated that; mainly due to the disappearance of milkweed in the U.S.; one billion monarchs have disappeared over the past twenty years! The U.S. Fish and Wildlife Service has been petitioned to declare them as threatened under the Endangered Species Act. This petition is currently under review.
Are Monarchs Good for the Environment?
Even though the monarchs travel in high numbers, they aren't exactly a plague like the biblical locusts. They actually play a significant role in the ecosystem.
On the one hand, they are excellent pollinators. While searching for food, they transfer pollen between plants, which helps the plants reproduce.
On the other hand, they are also a food source. Even though adult monarchs are poisonous to many birds, some birds like grosbeaks and orioles rely on them to make it through winter. Monarch caterpillars are a food source for spiders, wasps, and even ants.
The Best Places to See Monarch Butterflies
If you can make the trek out to the Biosphere Reserve in Mexico, you're in for a treat. An estimated one billion butterflies spend the winter here, spread out over fourteen colonies. Up to thirty million butterflies can live on the size of a football field!
The best time to visit is between November and March. Five of the fourteen colonies are open to visitors. The most visited sanctuary, El Rosario Santuario de la Mariposa Monarca, provides access to their largest colony. Here the monarchs cover around 1,500 trees.
The second most visited sanctuary and actually the one that is easiest to visit when driving from either Mexico City or Guadalajara is the Sierra Chincua Santuario de la Mariposa Monarca. Both are in Mexico's Michoacan State.
The Best Time at the Best Place to See Monarch Butterflies
Whichever sanctuary you choose, plan to arrive around noon. The butterflies love the sun and around noon – usually the warmest time of the day – is when you have the best chance of seeing thousands of butterflies in the air.
Each sanctuary offers tourist services such as guided tours (either on foot or horseback), food stands and parking facilities. A multitude of small hotels is available nearby the sanctuaries. If you are planning to drive from the U.S. to Mexico's Biosphere Reserve with your R.V., follow the "Route of the Monarchs" (Ruta de Monarcas) that follows the highway from Laredo, Texas (U.S. 35 to U.S. 85) to Mexico City.
The nearest R.V. park is available in the Pueblo Magico of Cuitzeo del Porvenir, next to Mexico's second largest freshwater lake: the San Juan del Lago Eco RV Resort. This is a great place to stay to see wildlife – wild horses roam the property – and an easy drive from the Sierra Chincua sanctuary. Follow the link above for more info and mention discount code "MONARCH" for a 10% discount.
Mexico’s Magic Towns Conjure Butterflies
The nearby town of Angangueo – another of Mexico's "magical towns", a designation given by Mexico's Secretariat of Tourism (SECTUR) to promote certain cities that offer visitors a "magical" experience due to natural beauty, cultural riches or historical relevance – hosts the annual "Monarch Butterfly Festival" (Festival de la Mariposa Monarca) in February with food, music and exhibitions.
The Best Place to See Monarchs in Texas
If you can't make it to Mexico, it is possible to see the colonies as they travel south during wintertime and north during springtime. One of my favorite locations is the Amistad National Recreation Area near Del Rio, Texas. This park, located on the U.S. – Mexico border, has hiking trails that allow for easy viewing of the butterflies. My preferred time of year is in October, although depending on the weather this can change yearly.
Sierra Chincua, The Trip of a Lifetime
As for my visit to the Sierra Chincua sanctuary this past February, the hike from the parking area to the butterfly colonies takes about one hour. Piece of cake I thought as I waved and said 'No, Gracias' to the guides asking if I wanted a horseback ride. Even though I'm in decent shape, the altitude definitely got to me, and I soon started wishing I was being carried to the butterflies on a horse. All my physical ailments disappeared as I witnessed the miracle that is the millions of monarch butterflies. This is the trip of a lifetime!
Be a Monarch Butterfly Citizen Scientist
During springtime, you can add to the monarch butterfly data base by logging your sightings or just follow the migration north at Journey North Sightings.
The journey south during fall is scheduled to be tracked by the World Wildlife Fund (WWF)
Video produced by Atlantic Public Media and the Encyclopedia of Life
Identifying Monarch Butterflies
A note from the Editor. As stated above, we made a mistake with our butterfly identification. Distinguishing monarchs from viceroy or queen butterflies can be difficult, particularly as butterflies tend to not be still for very long.
This The National Wildlife Federation chart makes the subtle differences in the butterflies’ patterns and colors more easy to recognize.
Our confusion identification underscores the fact that there are far fewer monarchs to compare. There are literally billions fewer monarchs than just a few years ago. We do hope you find monarchs this season. Why not plant some milkweed to help this wonderful creature to survive?
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