Monarch Butterflies, a Great Migration

A “must see” that’s been on our list for years is visiting the Monarch butterfly reserve in Mexico where all of the Monarchs in North America return every year. Unbelievably for us we booked our tour in the Reserva Mariposa Monarca at the same time as a group of women who were essentially masters of Monarchology. The women, who are from the northern regions of the Monarch migration, as far away as Iowa, Michigan and Toronto, came together in Cerro Pelon, one of the four reserves within about a 30 mile radius in Mexico.

Debbie is a self described crazed Monarch expert





These women are very knowledgeable and a lot of fun too!

We chose Cerro Pelon because although it was a smaller reserve it was a more intimate experience with just one group at a time going to see the butterflies. The tour began with a two hour horseback ride up some pretty steep terrain.




When it got too steep and narrow for the horses we continued on foot up even higher. This was not exactly a walk in the park as the trail was extremely steep at 10,000 ft. elevation with dry, dusty, loose dirt that sometimes had us taking one step up and two steps back.


I was amazed at the tenacity of this diverse group of women all of varying ages who trudged up this extreme hiking trail. They came here to see Monarchs damn it and by God they were going to see them! All along the hike we became more and more surrounded by the butterflies. We came to an area where our progress was stopped by a small rope cordoning off a section of the forest. The guides had us all sit down for a rest and we fell into silence and gazed into the forest. The trees seemed thick with heavily laden branches of dark clusters. Upon closer scrutiny these were enormous clusters of butterflies!


Those dark blobs in the trees in front of us are huge clusters of Monarchs.
Carol Pasternak wrote the book How to raise Monarch Butterflies

We sat with only the sound of cameras clicking and soft whispered murmurs for about an hour. It was truly magical. As we were getting ready to leave one of the women discovered that she had cell phone coverage at this altitude and made a quick call to her daughter in Canada. I overheard her say “I’m at 10,000 ft. and I’m surrounded by butterflies. It feels like I’m in heaven but I’m not dead!”

Ann and I were so amazed by this tour that we decided to stay another day and visit a second reserve, El Rosario. The colony there was significantly larger than the one at Cerro Pelon and from the reports we had heard we just had to check it out. This reserve was completely different and much more commercial but the walk was much easier on stone walkways and stairs. Within a short while we were inundated by the masses of butterflies.





They flew around us in swarms and would sometimes bump into us. If people remained silent, which sometimes they did, you could actually hear the sound of the millions of wings pulsing through the air. We saw them mating. Although the crowd of visitors was large, the sheer numbers of Monarchs at this reserve was well worth the trip to see them and we were delighted to have had both very different yet worthwhile experiences.

Anatomy of the Migration

I knew some of the basics of this astounding migration but the women filled in all of the blanks. In a nutshell the cycle goes like this:

The Monarchs return to this region of Mexico every year starting in late October and November where they hibernate over winter in huge clusters together and weighing down fir tree branches. The center of the cluster stays warm though many of the butterflies on the outer edges of the clusters die from the cold. The elevation of the reserves is about 10,000 ft. so it can get quite cold over the winter. In late February and March the sun warms the clusters and they explode into the sky in spectacular orange swarms as they shake off winter, drink water and begin their mating. One female can mate with several males as she prepares for the journey back north. In March the movement begins as this group of butterflies heads north to Texas and Louisiana where the females lay their eggs, usually on milkweed plants and then perish, their purpose being served. The eggs hatch and the caterpillars feed on the milkweed and then build their cocoons. In time a new generation of Monarchs emerges and mates and moves further north into the Midwest. This cycle repeats itself at least three more times with each generation reaching further north well into the great lakes region of the US and Canada. The fourth generation, at the northernmost portion of the migration, emerges from their cocoons as a kind of “super generation.” They have much larger, stronger bodies and thicker stronger wings. This generation makes the entire return from all parts north completely back to this relatively small region in central Mexico which overlaps Michoacan and Mexico states. It’s amazing to think that the butterflies of this “super generation” are the great grandchildren of those that left Mexico the previous spring. They will likewise hibernate over the winter, mate in Febuary and March and return only part way north as previous super generations have done for literally millions of years.

Yeah, we were pretty blown away too! The plight of the Monarch is under stress as well. Logging has shrunk the overwintering habitat in Mexico. Herbicides and invasive species has curbed the growth of milkweed numbers which are vital to the species continuation. When I told the ladies that we had milkweed and Monarchs and that I’d seen the caterpillars on our property in northern Indiana they suggested bringing the caterpillars inside where they would have a 95% chance of successful conversion to butterflies as opposed to a 5% chance in the wild. To anyone interested in breeding Monarchs one of the women on our tour, Carol Pasternak, has written a book, How to Raise Monarch Butterflies. You can find information and where to get a copy of the book at her website Carol says it’s very easy and a great project to get into with the kids. Other resources are and

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