WELLS — The U.S. Fish and Wildlife Service is using tiny transmitters called “nano tags” to study shorebird migration patterns.

The tags transmit signals to a network of radio towers that span the Northeast coast of the United States and Canada. Two of the towers are in the Rachel Carson Wildlife Refuge in Wells.

The technology makes this study different, said Kate O’Brien, a federal biologist who’s leading the project in Wells.

She told the York County Coast Star that fewer than 5 percent of birds that have a conventional band placed around a leg are ever recaptured, making it inefficient for tracking birds’ movement. She said the new technology uses a network of radio towers to track the 30 sandpipers she’s tagging this summer.

Data go to a central repository managed by Dr. Philip Taylor at Acadia University in Nova Scotia. Taylor is a pioneer in the use of radio towers to gather transmitted data.

The tags are extremely lightweight and transmit on a single frequency. Each transmission tower has three antennas, each pointing in a different direction to determine the bird’s location based on the strength of the signal received.

While using the same frequency, each uses a different burst rate so birds can be individually identified. “It’s like an individual pulse,” O’Brien said. “We record the pulse rate and send in the data.”

The Wells activity is the latest part of a larger project to study migration patterns of Semipalmated Sandpipers. That project, which began in 2013, is co-directed by Dr. Rebecca Holberton of University of Maine in Orono and Lindsay Tudor, shorebird biologist for the Maine Department of Inland Fisheries and Wildlife.

The project is one of several studying other bird and bat species being conducted by a broad collaboration of public and private organizations in the United States and Canada.

The project is just the beginning, Holberton said. “Last year was the first time for shorebird tracking in Maine,” she said. “This is the first year in Wells. It’s the first year with more than one site in Maine. We want to continue and expand to more sites in Maine and more species.”