Here is a detailed article on one of most inspiring natural excursions that is also part of Mexico’s Traditions, the surprising voyage of the Monarch Butterfly from North America to Mexico.
Year after year when autumn comes, following a millennial call whose origin remains a puzzle to Man, the monarch butterfly of North America undertakes the longest known voyage in the insect world.
After spending the summer months in the native fields and forests of central and northeastern United States and southeastern Canada, millions of these fragile insects start a 3,000 mile migration south so that they can enjoy the winter in central Mexico’s splendid Sierra Madre Oriental mountain range.
The destination during the voyage of the monarch butterfly (Danaus plexippus) was for a long while a unsolvable puzzle for researchers. But in 1975 the Canadian zoologist Dr.. Fred A. Urquhart, in partnership with Kenneth Brugger and Rafael Sanchez Castaneda, discovered their secret. The butterflies were enjoying the glacial period of winter in the dry brook beds and valleys of the high Sierra Madre mountains, at an altitude of 9 to ten thousand feet in an area that is in between the states of Michoacan & Mexico State, in the central area of Mexico.
Urquhart wrote about their discovery: “I watched in surprise at the view. Butterflies, millions and millions of monarch butterflies! They stuck in thickly packed masses to each and every branch and tree trunks of the tall, gray-green oyamel trees. They swirled thru the drafts like autumn leaves and covered the ground in their flaming colored myriads on this Mexican hillside.”
This discovery offered one of the most fantastic revelations regarding the insect world. All of a sudden, as if drawn by a powerful magnet, these fragile summer inhabitants of an enormous land area that covers over one half of the U. S. , fly south in hurried droves in a voyage that takes them south over lush prairies, deep valleys, high mountains, dry deserts and towns, crossing the Mexican-American border through Texas, to come together by the millions, like orange-colored tributaries of some great brook, into an area in central Mexico where the Sierra Madre and the Volcanic Belt mountains link up.
A comparatively small wooded area of only 12,500 acres is the refuge where the monarch butterflies spend the winter and mate before flying north again in the spring.
Though this seemed to be a wonderful discovery for the scientific community, it was a fact widely known to the area’s inhabitants. These creatures had been part of their daily lives since times long past. Pre-Hispanic inhabitants attached a lot of importance to the monarch butterfly, which played a significant role in their local religion, legends and myths, and were widely shown in their art.
Connected with fire and the movement of the sun, butterflies or papalotl represented the spirits of soldiers who had died in battle or on the sacrificial altar. It was thought that after travelling with the Sun for four years, they might come back to earth as a butterfly, to enjoy the sweet nectar of flowers. This belief, in all probability, also applied to monarch butterflies, “daughters of the Sun” whose yearly migration represented the replenishing cycle of Nature.
In 1986, eleven years after Urquhart’s discovery, the Mexican Govt protected this ecologically important mountain area by establishing the Monarch Butterfly Special Ecosphere Reserve. A total of around forty thousand acres of forest were declared protected areas for the migration, wintering and reproduction of the monarch butterfly, as well as for the conservation of its vital environment.
The Monarch Butterfly’s Summer Residence
During the summer, monarch butterflies live in an area including 1.5 million square miles and that extends from southern Canada to the southern tips of the Sierra Nevada, the Rocky Mountains to the West and the Appalachians to the East within the borders of the United States of America. This area has a rich bounty of milkweed (Asclepias), the sole plant on whose leaves the caterpillars of this species can feed. This plant also includes a noxious alkaloid that makes the caterpillar immune to many natural predators, and provides the natural pigment which gives these butterflies their identifiable coloration.
The longer days and high summer temperatures of this region allow the monarch butterfly to grow and reproduce. During those months, its life cycle is like that of any other butterfly. They live from 2 to six weeks, in which they reproduce, lay their eggs and, shortly thereafter, die.
However , the generation that comes forth from the cocoons under the Sep sun has a very different destiny than that of its folks and grandparents. After the fall equinox, as the days grow shorter and temperatures go down, the autumn butterflies undergo a sequence of hormonal changes which inhibit their reproductive system, preventing sexual maturity, and letting them save energy and survive much longer than their progenitors.
Instead of generating the urge to pair, the shortening days create in these creatures another insistent need, of similar importance for their survival as reproduction… An urge to journey south, towards warmer areas where they can live through the winter chills, postponing their reproduction cycle until the following season.
So, they must travel to preserve the species. If they survive the dangerous journey, they can live as long as nine months, twelve times longer than any other butterfly.
The Amazing Monarch Journey
After storing enough energy and body fat in the summer months, these indefatigable travelers will fly as much as three thousand miles to reach their Mexican wintering grounds. They fly all day 24×7, and rest in the night, sleeping on tree branches in groups of at least 600 butterflies.
Dependent on the winds, they can travel at a velocity from nine to twenty-seven miles an hour, covering as much as 80 miles in daily eight-hour shifts. Their favourite routes lie along low open valleys, where they can best take advantage of the north winds to push them along in open-winged glides, which enables them to fly long distances easily. This is the way the monarch butterflies can make their 3,000 mile journey in only one month.
By mid-November, the green ravines of the Mexican butterfly sanctuaries, covered with oyameles or firs, oaks and spruces, change to shades of ochre, brown and orange. Leaves and pine needles become covered with a unique texture made by the wings of the uncountable millions of butterflies that hang in thick groups, from the tree branches and tree trunks. Here they live through the winter cold, in a condition of semi-hibernation that lets them save their energy and fat until spring arrives once again.
The Monarch Butterflies Return
Warmer days and longer daylight hours send their age-old signals to the sleeping monarchs telling them that spring has returned. They start to stir and flap off the sleepiness of their long sleep. They slowly open their wings to let the sun heat in and to warm their bodies.
Slowly the air comes alive and orange tinted, with hundreds and hundreds of butterflies that fly around from flower to flower ingesting the sweet nectar that will nourish and give them strength and stamina for their homeward flight.
Light, heat, and their new-found freedom stimulate their sexual maturity. Their buried instincts take over, giving way to courting rituals and mating. And then, without further circling, just as when they all of a sudden started their trip south 5 months before, as if moved by an internal clock that urges them to go back home, they start their return journey. Clouds of butterflies rise up into the air, their beating wings generating a muted throb in pursuit of air currents that will carry them away.
Their numbers have already been lessened. Many have died of the rain or from the winter temperatures. Mating has also taken a toll on the majority of the males, who invested their last energy supplies in the reproductive act, and then perished.
But among the survivors are a large number of fertilized females who, during their way back home, will deposit their eggs on their nightly stops to rest. Two weeks later these eggs will hatch into caterpillars, which will soon become chrysalis that, in the late spring, will metamorphose into butterflies.
Of these, only a few will remain to copy the cycle there, where they were born. The rest will continue northward to a home they don't yet know, where, like countless generations before them, they are going to live, friend and die. And it will not be their young, or their offspring’s young, but the next generation of butterflies, those born at the end of summer that may again respond to the call to migrate south, as their ancestors did the year before, beginning another cycle.
The Mysteries of the Sovereign Butterfly
It is still a mystery how these tiny, fragile insects know which road to follow, since the winter visitors were born in the far-off forests of the U. S. and Canada, and the sovereigns reproduced in Mexico will never return there.
How does a complete generation of monarchs travel a several thousand mile route that neither they, nor their parents, have ever flown before? How do their descendants, born after the winter season along the migration back north, find a way to return to their parents’ place of origin?
Again, how does such a little, frail and exposed creature find a way to survive the rigors of traveling such long distances exposed to the sun, the rain, the cold and the depredation of man? Where does such a little body accumulate so much energy? What makes it so tireless? How can an insect be so superb?
Many answers have been suggested for these paradoxes, but still none is conclusive. But one thing is clear. The monarch butterfly is one of the most astounding creatures on this world. And, the more we know about it, the more extraordinary it becomes.
This long distance traveler, citizen of the planet, is the most fragile and gorgeous symbol of the transformation and renewal of Nature. Above all else , it's a prime example of a species’ instinct to survive.
No wonder our ancestors venerated the Monarch Butterfly and that’s why it’s so important that we protect them.
Guadalupe Q. Pali is a mag editor in Mexico, writes many articles on traveling in Mexico and its natural marvels, including some like What to do in Puerto Vallarta, that is part of the Puerto Vallarta’s Travel Guide
web site.