Last season, 60 Minutes witnessed the remarkable autumn migration of monarch butterflies to the mountains of central Mexico. What once was a largely mysterious, population-level phenomenon is now being examined at the level of individual insects. Scientists are attaching tiny, solar-powered radio tags to monarchs to follow single butterflies on their long journeys and to learn how they navigate, where they stop, and what threatens them along the way.
How the tags work
The radio tags used in this work are miniature, light enough to be carried by a butterfly, and equipped with small solar cells to extend battery life. Each tag transmits an identifying signal that can be detected by networks of receivers, by mobile tracking teams, or by research stations positioned at strategic points along migration corridors. Because the tags broadcast unique identifiers, scientists can distinguish individual flight paths, stopover durations and timing, and movement responses to weather and habitat conditions.
What the tracking reveals
Individual-based tracking yields specific insights that broad-scale monitoring cannot. Researchers can document how far a single monarch flies each day, whether it drifts with winds or compensates with directional flight, and how often it pauses to feed and refuel. Tag detections show where monarchs concentrate for rest, where they forage, and the microhabitats they use en route. That level of detail reveals variation in behavior within the population: some butterflies take more direct routes, others make more frequent stops, and survival rates can differ dramatically from one individual to another.
Conservation implications
The data from tagged monarchs help refine understanding of which habitats and resources are most important during migration. For conservationists, those findings guide priorities: protecting nectar corridors and safe stopover sites, promoting native milkweed and nectar planting, and identifying risky stretches of the landscape where mortality or disorientation is high. The tracking also helps clarify how weather events, agricultural changes, and urban development affect migratory performance and survival. By pinpointing bottlenecks and critical refuges, managers can focus restoration and policy work where it will benefit the migration most.
Challenges and ethics
Attaching devices to delicate insects requires careful engineering and field protocols to avoid harming the butterflies or interfering with their behavior. Researchers calibrate tag weight and attachment methods, and they validate that tagged individuals behave like untagged ones. Detection coverage is another constraint: receivers and mobile teams must be deployed across broad regions, and detection windows can be brief. Despite these limitations, solar-powered radio tags are extending the season and range of possible observations beyond what earlier methods allowed.
Looking ahead
Individual tracking of monarchs is expanding knowledge of a complex, multi-generational migration that spans thousands of miles and crosses international borders. The approach complements population surveys and overwintering counts, giving conservationists the actionable detail they need to design corridors and protect stopover sites. As the technology improves and networks of receivers grow, scientists expect to fill more gaps in the monarchs’ life-cycle map and to develop better strategies for sustaining one of the world’s most celebrated insect migrations.
I’m Anderson Cooper. We’ll be back next week with another edition of 60 Minutes.
