Project Monarch: The Monarch Butterfly’s Epic Migration

When the days begin to shorten, the air becomes cooler, and milkweed begins to fade, North America’s migratory monarch butterflies (recently listed as endangered by the International Union for the Conservation of Nature (IUCN)), turn south as their kind have for millions of years. This is the start of one of the planet’s great migrations.

So it begins. Monarchs are on the move. It’s fall in the Northern Hemisphere, when migratory monarch butterflies begin their 3,000-mile journey south from their summer homes scattered across the northern, central, and eastern swaths of the United States to their overwintering grounds some 10,000 feet above sea level in the mountains of central Mexico.

Weighing as much as a sunflower seed, these incredible insects take an absolutely epic adventure south and over cities, through farms, and across forests, grasslands, and mountain valleys. During this time of year, Hipcamps become critical fueling stations for these migratory monarchs, who are looking for places to rest along the way. Without suitable habitat filled with milkweed and other native wildflowers, migratory monarch butterflies are at risk of disappearing forever.

Recent studies from the IUCN suggest that among monarchs, “the western population is at greatest risk of extinction, having declined by an estimated 99.9%, from as many as 10 million to 1,914 butterflies between the 1980s and 2021. The larger eastern population also shrunk by 84% from 1996 to 2014. Concern remains as to whether enough butterflies survive to maintain the populations and prevent extinction.”

“The western population is at greatest risk of extinction, having declined by an estimated 99.9%, from as many as 10 million to 1,914 butterflies between the 1980s and 2021.”

The task at hand is of monumental importance: to save the migratory monarch. In order to do so, we must appreciate their fantastically amazing life, one defined by long migrations.

Not all monarchs migrate south, but those that do are known as the “super generation.” These butterflies are bigger and stronger than their recent ancestors, and live four times longer than them—up to 9 months longer than most other butterflies! The super generation’s existence is made possible by an intergenerational relay of monarchs required to complete this migration, which starts in spring.

From the beginning: Heading north in spring

At the start, a new generation hatches from the underside of milkweed leaves, growing from caterpillar to brilliant orange adults. These adults—known as generation one—then continue north. This cycle unfolds another 2 or 3 times, as generations of migratory monarchs hopscotch north until peak summer, when they reach their northernmost destinations scattered across the US and southern Canada. By late summer, when milkweed has again faded and the air cools to signal the steady start of fall, a new super generation is born. These are the bigger, stronger monarchs who take the epic migration south in one massive flight, covering thousands of miles.

Midpoints of the monarch migration by latitude

An impressive journey south

So how does an insect with a brain the size of a pinhead make this epic migration? How do they know where to go?

In order for this super generation of migratory monarchs to navigate the long journey to the pine forests of Central Mexico, they rely on a tiny solar compass stored in their heads. Traveling 10 to 30 miles each day, monarchs find their way by reading the position of the sun on the horizon and using their two small antennae, which serve as a an internal wristwatch of sorts. By using their solar compass and antennae, the monarchs can point themselves in the correct direction even when it’s cloudy! Their eyes have cells that allow them to pick up even the faintest signals from the sun using polarized light.

By mid- to late November this super generation of wayward fliers will have completed their final leg, arriving in their winter refuge high in the mountains of Mexico, where the relatively stable and mild weather (not too cold, not too hot) carries them through what many scientists describe as a sort of hibernation period. The monarchs don’t eat during this time—instead, they live on fuel reserves built up during their journey, sometimes nectar harvested from Hipcamps and milkweed fields along the way.

This is just a quick look into the wonderful world of the migratory monarch butterfly. Their preservation into the future is not guaranteed. In fact, we’re far from it. And yet, we have the opportunity to save them before it’s too late.

Get involved

Learn more about our efforts to save the migratory monarch butterfly and sign the pledge to do your part. You can also watch our Project Monarch webinar series in which a panel of experts and scientists discuss best practices for monarch conservation.

Support Hosts committed to protecting the monarchs

Read on for more on Hipcamp’s work to leave it better

Discover more important stewardship stories from Hipcamp Hosts making a difference.

• Introducing Project Monarch: A Letter from Hipcamp Ecologist Charles Post
• 10 Unique Ways to Leave it Better
• These Hipcamp Hosts are Making the World a Better Place
• How to Make DIY Seed Bombs to Grow Wildflowers
• How to Recreate Responsibly During COVID-19