Published: April 8, 2019

Following the Monarch Butterflies to Mexico

Abigail Derby Lewis, Interim Chicago Region Program Director, Keller Science Action Center

The hidden forest where they spend the winter is a sight to behold. 

Image slideshow

Screen reader users can skip the following slideshow buttons by using heading navigation. All slides have been displayed above.

The monarch population this year is estimated to be 225 million, the highest recorded number since 2006 and an increase of 144 percent from last winter. Being in the forest and actually seeing the scale of this migratory phenomenon simply takes your breath away. At first, it’s not even clear what exactly you’re looking at. It takes a moment to focus and to realize that the trees are completely covered with monarchs! A butterfly is resting on every single pine needle of every branch and covering every square inch of the tree trunk.

There are so many butterflies that they weigh down even the tallest and most majestic fir trees, giving the appearance the whole forest is dripping with monarchs.

Abigail Derby Lewis

Monarchs and the "magic towns"

El Rosario Sanctuary is a short drive from where we stayed in the mountain town of Angangueo, one of Mexico’s Pueblos Mágicos or “Magic Towns.” A small community 75 miles west of Mexico City, Angangueo is surrounded by the pine-oak forests hovering over 8,000 feet above sea level along the Trans-Mexican Volcanic Belt. The tile roofs, stucco buildings, churches, cobblestone lanes, and brightly colored homes clinging to steep hillsides are imbued with beautiful artistry and history.

For centuries, the indigenous Purépecha Indians who lived in Michoacán tracked the butterflies’ fall arrival, calling them the Parákata, or “harvester butterfly,” because their return signaled it was time to harvest the corn. The Purépecha also believe monarch butterflies are the souls of their deceased ancestors who annually return for a brief visit (see our storybook on the Legend of the Parákata). Today there is still a strong connection between the people living in Angangueo and the monarchs.

An uncertain future—but there’s something we can do

Forests, and nature in general, are the places I often feel most spiritually connected. Witnessing a migration of this magnitude in such a special place was restorative on so many levels. It was a deeply satisfying and joyful feeling to look around and know that many of these butterflies may be the children of the monarchs we raised in our backyards last summer, or perhaps even the individuals we saw stopping to feed and fuel up on asters, goldenrod, and other late-blooming native flowers in the Chicago region last fall as they made the southward journey back to Mexico.

The population increase is certainly something to celebrate, and I was thrilled to hear the good news shortly after returning from my trip. It’s important to bear in mind, however, that the annual population does rise and fall, and it’s had an overall downward trend for the past 20 years. The numbers this year represent the minimal threshold experts think is needed to keep a viable migrating population. I think the increase certainly reflects some success of large-scale efforts to create habitats in the summer breeding grounds of the United States as well as to reduce illegal logging at the overwintering sites in Mexico.

But the boost in numbers likely also reflects a Goldilocks effect in last year's weather: not too hot, not too cold, and few storms. As climate change begins to increase temperature, drought, and the frequency of extreme storms throughout the monarchs’ range, they will no doubt face additional challenges—making actions to provide more milkweed and nectar sources for them even more critical.

To be able to see this wondrous part of their life cycle helped me fully appreciate the complexity and remarkable nature of this species. It fueled my desire to double down on our efforts to engage communities in scaling the creation of habitat throughout metropolitan areas in the Midwest and beyond. Our research shows that adding milkweed and native flowers to our backyards, community gardens, balcony pots, and rooftops will help monarchs and a whole host of other pollinators, too—what we plant really matters.

Spring is upon us, and it’s time to start thinking about what to plant. Need some ideas to get started? Browse our monarch habitat Field Guide for recommendations on plants that will support monarchs and other pollinators.

Abigail Derby Lewis
Interim Chicago Region Program Director

I began my professional career as a biological anthropologist studying primate behavior and comparative ecology. This path allowed me to live and work in some of the most biodiverse and threatened regions in the world, and fostered a profound and personal interest to become involved in applied research initiatives that contribute to sustainable management and environmental policy in a meaningful way. The transition to working on climate change impacts to biodiversity in the Chicago Wilderness region was a natural progression that grew from my graduate work on human-wildlife interactions. A main goal of my current work is to help build and renew positive relationships between people and the environment as sustainable partnerships that communities are empowered to create and continue.Professional: Past and present climate change; Historical and current interactions between humans and the environment; Climate change impacts to biodiversity; Landscape and ecosystem-based approaches to mitigation and adaptation; Comparative ecology; Climate science education.

Personal: Being outdoors in any capacity (hiking, biking, kayaking, camping); Gardening and native landscaping; Supporting the local live music scene; Creative cooking; Travel, travel, travel.