Wednesday, May 10, our students gathered together to embark on an epic journey wherein they traveled from Canada and the United States to the awe-inspiring butterfly forests of Mexico.
This virtual field trip, “Magnificent Monarchs: The Great Migration,” taught our students about one of the greatest migrations in the animal kingdom and about the story behind the discovery of the overwintering sites for these majestic creatures.
Upon arrival in Mexico, we discovered that not all monarchs migrate; however, for those that do, including the Eastern North American monarchs, 80 percent of these animals spend their winters largely in a 73-by-73-mile area in the Mexican states of Mexico and Michoacan. The butterflies choose to overwinter here, scientists say, because the weather is perfect in this area, which encompasses a region known as the Transvolcanic Belt.
These small winged travelers have the longest migration of any of their monarch cousins found around the world, traversing, in some cases, a distance of 3,000 miles! Other North American monarchs settle for the winter along the Gulf coast or in California.
The butterflies begin their journeys in mid-August through late September and arrive to their winter homes around November 1. Interestingly, in the regions where the butterflies land, November 1 is also a holiday known as the Day of the Dead, or “Dia de los Muertos.” It is considered auspicious for the butterflies to arrive on or before this date as many believe the butterflies to be the souls of friends and relatives who have passed away. It is seen as bad luck when the butterflies do not arrive by November 1.
On this virtual field trip, we visited one of the 12 overwintering sites—Piedra Herrada in the state of Mexico.
Here, we saw how the butterflies settle high in the mountains—some as high as 10,000 feet—and “roost” (otherwise known as “hang out in the trees”) for the entirety of their stay. The creatures do not mate or even eat during their time in Mexico; they simply gather together for warmth, settling in huge groups—or “colonies”—in the soft wood trees with flexible limbs that bend but do not break under the weight of thousands upon thousands of butterflies.
Nine to 15 percent of these monarchs get eaten by birds. Though the monarch is toxic, thanks to its diet of milkweed in its youth, certain birds—including the oriole—have found a way to eat just the butterflies’ insides, bypassing the toxic wings and exoskeleton.
The travelling monarchs do however have a vastly longer lifespan than ordinary generations of monarchs. While most monarchs live two to six weeks in total, the monarchs who travel live for closer to nine months.
After enjoying their relaxing time roosting in the soft wood pines of their winter homes in Mexico, the butterflies begin their journeys back north around early March. These creatures lay their eggs in Northern Mexico and Texas and will then die, and the new generation of butterflies goes back to the short life cycle of two to six weeks.
One facet that is certain, however, is that in order for the baby butterflies, or caterpillars (larvae), to survive, they must have milkweed to eat. Milkweed is the only plant that monarch caterpillars will eat, thus this plant is vital to the survival of these creatures.
How these butterflies know to return to the same forests in Mexico year after year remains one of science’s great mysteries. Students can visit Monarchwatch.org for more information about how to help tag and track these wonderful creatures.
What is known, however, is that no matter one’s place in the world, one can work to help protect these delicate insects.
Less than one percent of monarch caterpillars survive into adulthood, as they have so many natural predators; for this reason, and because of loss of natural monarch habitat throughout North America, it is vitally important to preserve, protect, and plant gardens that can be welcome homes to the monarchs.
One way to help our butterfly friends is to plant a butterfly garden featuring flowers that bloom in the late summer as well as milkweed, the staple food of the butterfly larvae. This will help fatten the creatures up for their long journeys south and will provide safe harbor for butterflies looking for a place to lay their eggs.
To learn more about the natural wonder that is the great monarch migration, view a recording of our virtual field trip here.