North America – Monarch butterflies complete a remarkable annual migration that covers thousands of miles across Canada, the United States, and Mexico each fall.
Over 400 Butterflies Tracked in Real Time
Over 400 Butterflies Tracked in Real Time (Image Credits: Imgs.mongabay.com)
Researchers achieved a milestone in 2025 by attaching ultralight radio tags to more than 400 monarchs, marking the first comprehensive, near-real-time monitoring of individual insects during their journey to Mexican overwintering sites. This breakthrough shattered previous limitations, as earlier tracking methods could not follow butterflies over such vast distances. Scientists captured detailed paths from release points in Ontario and New Jersey all the way to the Monarch Butterfly Biosphere Reserve.
The tags revealed surprising detours, including one butterfly blown toward the Bahamas before heading to Florida. Another took a coastal route through the Florida Keys. These observations highlighted the variability in migration strategies.
The Ingenious Design of BlūMorpho Transmitters
Cellular Tracking Technologies developed the BlūMorpho tags, each weighing just 60 milligrams – about the weight of three grains of rice and a fraction of a monarch’s 500-milligram body. A tiny solar panel, the size of a rice grain, powers the device, which broadcasts signals at 2.4 GHz, the same frequency as Bluetooth. Technicians applied them using eyelash glue to the butterflies’ thorium without hindering flight.
Detections occurred through the free Project Monarch app, turning smartphones into receivers within a quarter-mile range. Networks like Motus and crowd-sourced devices amplified coverage, yielding hundreds of pings per tag. This setup enabled precise mapping of daily movements and stopovers.
Partners Unite for Continental Coverage
Project Monarch united over 20 organizations across four countries, including the Monarch Joint Venture, Xerces Society, Birds Canada, and Monarch Watch. Monarch Watch alone deployed 30 tags on butterflies in Kansas late in September. Of those, 30 percent reached Mexico, 63 percent passed through Texas, and 70 percent were detected in Oklahoma.
- Cape May Point Arts and Science Center funded early tests.
- Environment and Climate Change Canada tagged monarchs at Long Point, Ontario.
- Xerces Society and Point Blue focused on California’s western population.
- Mexican partners like CONANP searched overwintering grounds.
This teamwork standardized protocols and shared data via the Blū+ Portal, creating a vast detection network.
Revelations Reshape Migration Understanding
Tagged butterflies crossed Lake Erie, navigated urban Ohio, and flew over 100 miles along California’s coast in days. One monarch, ML004, traveled from Moran Lake to Cambria, while others ventured inland to UC Santa Cruz sites. These patterns showed frequent urban flights, emphasizing nectar needs in communities.
Early arrivals hit Mexican colonies on November 9. Researchers noted no major survival impacts from tags when applied correctly. Such data addresses gaps in the migratory life stage, long shrouded in mystery.
Boosting Conservation Amid Declines
Monarch populations face steep drops, with North American butterflies down 22 percent over two decades and western monarchs by over 99 percent since the 1980s. Tracking identifies critical habitats and routes for protection. “The tagged butterflies will help us understand when and where monarchs move,” said Emma Pelton of the Xerces Society.
Cheryl Schultz of Washington State University called the technology “amazing,” noting its potential to aid declining insects. Future efforts plan spring tracking from Mexico northward.
Key Takeaways
- Ultralight 60mg solar tags enable first continent-spanning monarch tracking.
- Over 400 butterflies monitored in 2025, revealing diverse paths to Mexico.
- Data supports habitat protection amid population crashes.
These insights promise stronger strategies to safeguard monarchs. What steps can communities take to support their journey? Share your thoughts in the comments.
