Cellular Tracking Technologies’ BlūMorpho transmitter on a Monarch Butterfly.
Courtesy Cellular Tracking Technologies

I long to look up at the blue September skies. The older I get, the more I look forward to scanning the horizons for winged beauty. Migrating songbirds, lingering shorebirds, early waterfowl and raptors, and even nonfeathered friends begin their journey south. Red Bats are often seen roosting in bushes, their reddish fur blending with the first tinge of fall color that perfectly hides their daytime slumber. But one migration brings back a memory that, to this day, remains at the foundation of my lifelong love of the natural world: the southern journey of the Monarch butterfly.

MIKE MILLER

That autumn movement is more than a seasonal marker for me; it is tied to one of my earliest memories of feeling wonder in the presence of wild things. I remember a time in grade school when a sunny September day outside the classroom windows had me watching the clock in anticipation of recess. When the bell rang, it was a race out the doors. School was just back in session, and everyone longed for the brief freedom that a 15-minute break from the classroom promised. As usual, I bypassed the playground crowded with loud kids weaponizing rubber 4-square balls. Poking among the weeds at the edge of the woods was more my style. On this particular day, as I approached the tree line, the woods seemed more alive than usual. Monarch butterflies by the hundreds were roosting in an old hedgerow. They had sought night refuge there and were just coming out of their slumber, taking flight as the sun warmed the skies for the next stretch of their journey. It was a sight that has always remained one of those moments that cemented my lifelong interest in nature.

Monarch caterpillar snacking on Sullivant’s Milkweed in a local butterfly garden.
Mike Miller

In the Nature Rambles column of the September, 2025, issue of Community Word, I detailed the fascinating, multi-generational migratory journey of the Monarch. Our understanding of that migration is fairly recent. It was built on decades of research involving butterflies marked with uniquely numbered, ultralight wing tags. Imagine the odds against ever finding a previously tagged Monarch. It was a slow process, but around 1975, researchers had enough data to point to the existence of a migratory route between Canada and the oyamel fir forests in Mexico. While overwintering Monarchs in Mexico have been known about for centuries, the scope of their incredible 3,000-mile, migratory journey has been understood for only a few decades. A few years after my personal butterfly enlightenment, I picked up the August, 1976, issue of National Geographic. The cover depicted a person surrounded by Monarch butterflies so densely packed that the tree they were perched upon could not be seen. Inside, the story detailed how Dr. Fred and Norah Urquhart — after years of tagging butterflies — finally located the massive overwintering colonies in Michoacán, Mexico.

A lot has happened since the mystery of Monarch migration was cracked. Decades of additional wing-tag data has led to a better understanding of the precarious nature of migration. There have also been efforts to preserve the mountainous forests in Mexico and improve habitat in the U.S. and Canada, both crucial to the successful survival of Monarchs. These efforts are paying off. In the last two years, overwintering populations of Monarchs in Mexico have increased by more than 60 percent.

Over the last year, an alternative to numbered wing tags has been developed. The company Cellular Tracking Technologies has developed micro-sized radio tags small enough to be carried by Monarch butterflies. Butterflies with these tags can be monitored in near real time. The Project Monarch Collaboration has brought butterfly migration monitoring into the digital age. Initial observations have brought new insights to light and opened a whole new realm in our ability to learn more about migration. Undoubtedly, this new data will bring as many questions as answers. That’s the amazing thing about nature. The wonders do not diminish with knowledge. Ask any kid who just saw their first butterfly and wanted to learn more.