By MEG HEDEEN
For the first time ever, we’re getting a behind-the-wings look at the incredible journey monarch butterflies take to reach their wintering grounds in Mexico.
This past fall, hundreds of monarchs were fitted with tiny yet powerful tracking devices. Each contains a BlūSeries tag that transmits the same frequency used by Bluetooth devices, allowing the butterfly’s location to be recorded whenever it comes within range of a signal. Miniature solar panels power the tags, enabling them to function far longer than traditional battery-powered trackers.
It may sound like a lot for a delicate butterfly to carry, but this tag created by Cellular Tracking Technologies weighs just 0.06 grams, roughly the same as a grain of rice. That’s about 10 percent of the monarch’s body weight.
Yet despite their size, these tags are revolutionizing how we study monarch migration. Previously, researchers used small sticker tags to track monarchs. While this method taught us a great deal about how far and fast monarchs can travel, it relied on people spotting and reporting the tags.
This fall marked a monumental leap forward in monarch research. Thanks to the Project Monarch app and the broader smart device network, we can now trace the full migration path of each tagged butterfly. For example, we can see that a monarch butterfly tagged in Harrisburg, Pennsylvania, on Sept. 23 followed the Appalachian Mountains south, flew across northern Georgia in the first days of October and reached its wintering site in Mexico by Nov. 9.
Monarch migrations tracked as of Nov. 20 (Cape May Point Arts and Science Center)
Want to know more? Download the free Project Monarch app from your device’s app store to view migration paths and help collect data. You can also report monarch sightings and nectar plant visits to the Xerces Society’s Monarch Nectar Plant Database to support regional conservation efforts.
Meg Hedeen is a wildlife biologist at the U.S. Fish and Wildlife Service field office in Athens.
REPORT WINTER SIGHTINGS
On a related note, Monarchs Overwintering in the Southeastern States (MOVERS) is again asking the public to report monarchs spotted this winter in southeastern and Gulf states to Journey North or iNaturalist. Sightings – more than 6,300 have been reported since 2020 – can help scientists better understand this aspect of migration and how, or if, it affects the overall monarch population.
At Journey North, create a free account, learn how to report monarch sightings and submit observations November-March. Or, for the same time period, create a free account at iNaturalist and enter sightings using your web browser or phone app.
Want season updates? Join the iNaturalist monarch winter project.
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