Tracking Monarchs on the Move
BlūMorpho tags are tiny, solar powered radio transmitters designed to track individual monarch butterflies throughout their migration. Weighing just 60 milligrams, about the weight of a grain of rice, they are light enough to attach to a monarch without burdening it in flight. The tags are attached to the butterfly’s thorax with eyelash glue and transmit a unique signal that allows researchers and community scientists to follow individual monarchs as they travel.
Creating a transmitter light enough for a monarch was the biggest design challenge Cellular Tracking Technologies (CTT) engineers faced. Larger batteries with longer lifespans would simply be too heavy, so engineers developed a tiny radio transmitter powered entirely by a small solar panel. The panel harvests enough energy from sunlight to send a brief transmission, meaning that as long as the tag has access to light, it can continue transmitting roughly once per second indefinitely. The tags have no battery, which is what allows them to remain so lightweight.
The tags operate on the 2.4 GHz frequency range used by Bluetooth, allowing nearby smartphones and other compatible devices to detect them. Through the Project Monarch Science app, people can help detect tagged monarchs in their area, turning everyday community members into part of a distributed tracking network. The more Bluetooth and location enabled devices participating in the network, the more opportunities there are to detect a tagged monarch and add another data point to its journey.
There are plenty of citizen science opportunities for our Lower Shore community. This year, the New Hampshire Audubon Society is participating in Project Monarch, deploying BlūMorpho tags to follow the journey from northern New England to the Gulf of Mexico. We’re proud to be one of several partners supporting this effort by planting “stopover” habitat, providing food sources like milkweed along the way. Since early spring, we’ve been renovating the pollinator garden at Sturgis Park right here in Snow Hill, with the goal of becoming one of several official Monarch stopover sites along the southern migration route.
Taking part in this project has underscored the value of small, connected patches of habitat, which provide the fuel monarchs need for such an energy intensive journey. Monarch caterpillars feed exclusively on milkweed (Asclepias species), and adult monarchs rely on nectar from flowering plants to fuel their migration. As they make their way south, eastern monarchs eventually reach their overwintering grounds in Mexico, where they cluster in high altitude fir forests to stay warm through winter. When spring arrives, they begin the journey north again, continuing the cycle and searching for milkweed on which to lay their eggs.
The ability to track individual monarchs throughout this journey is giving researchers a much closer look at how these butterflies move across the landscape and where they stop along the way. Project Monarch has already tracked individual monarchs thousands of miles, including butterflies that made it to Mexico and later began their northward journey again. For a species that depends on a network of habitat across an entire continent, understanding these movements can help us better understand where habitat is needed and why those small patches of food and shelter can make such a difference.
Keep an eye out in your own garden and let us know if you spot a monarch wearing a BlūMorpho tag!
Other resources include Project Monarch Collaboration, Monarch Joint Venture: Monarch Migration, and U.S. Forest Service: Monarch Butterfly Migration.
