Solar Radio Tags Track Monarchs Across 3,000 Miles
Tracking data shows an eastern monarch reaching Utah as the federal protection decision remains pending.
Updated on Nov. 3, 2026 in Environmental
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Scientists attached solar-powered radio tags to nearly 1,750 monarch butterflies this year, with tracking that began last year. The tags, developed by Cellular Tracking Technologies, cost $200 each and weigh about as much as a drop of water. The work is field research, not a product, and it is tracking monarchs that migrate some 3,000 miles from as far as southern Canada to central Mexico.
Why it matters
The tracking shows routes that were previously hard to observe, including the first evidence of a butterfly from the eastern population reaching Utah, west of the Rockies. The data arrives as both monarch populations have fallen sharply since the mid-1990s, with the eastern population down more than 80% and the western population down about 95%.
The tags are solar-powered radio transmitters that cost $200 each and weigh about as much as a drop of water, allowing researchers to follow individual butterflies. Tracking data records where monarchs roost each night and how far they fly each day, and the first Utah observation was drawn from this data.
The players
Cellular Tracking Technologies
A company that developed the solar-powered radio tags used to track the monarch butterflies.
Trump administration
The U.S. government administration that delayed a decision on federal protections for monarchs last year.
The details
Scientists attach tiny solar-powered radio tags to hundreds of butterflies to track their routes, which lets them follow individual insects across a journey of roughly 3,000 miles. Trackers record where monarchs roost each night and how far they fly each day, building a route map for each animal. Monarchs begin migrating in response to environmental cues such as temperature. Human-caused climate change keeps northern areas too hot for too long, so the monarchs do not receive the cues that trigger migration.
Timeline
- Mid-1990s: eastern and western monarch populations began their steep declines.
- Last year: tracking began and the Trump administration delayed a decision on federal monarch protections.
- This year: solar-powered radio tags were attached to nearly 1,750 monarchs.
- 2030: court-ordered deadline for a final federal decision on monarch protections.
The Tech Race
Solar-powered radio tags have become a tool for following insects over distances of thousands of miles, extending the kind of individual-animal tracking previously used on larger migratory species. The tagging work is research-stage field science, and its route data feeds a federal protection decision that the government has yet to finalize.
The tracking data may inform how monarch habitat is managed across North America, though the stub does not indicate any change for the public. Tagging is currently a research activity, and no consumer-facing tools or access points were described.
The takeaway
Watch whether the court-ordered federal decision on monarch protections arrives by 2030 and whether it draws on route data like the new Utah observation. The population declines are the measure to track, since the eastern population has fallen more than 80% and the western population about 95% since the mid-1990s.
What happens next
A court has ordered the government to make a final decision on monarch protections by 2030.
Further reading
For more on the research behind these routes, see our Environmental coverage.
Source note: This article includes information reported by Irish Examiner.
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Should the federal government do more to protect monarch butterflies?
