WELLS, Maine — The U.S. Fish and Wildlife Service is participating in a groundbreaking study of shorebird migration patterns, using cutting-edge technology to track the birds and record their data.
The technology includes lightweight radio transmitters, known as nano tags, attached to shorebirds. The tags transmit signals picked up by a network of radio towers that span the Northeast coast of the United States and into Canada. Two of the towers are in the Rachel Carson Wildlife Refuge in Wells.
Kate O’Brien, a USFWS wildlife biologist, is leading the project in Wells. She said the technology is what makes this project different.
“Less than 5 percent of [traditionally] banded birds are ever [re]caught,” O’Brien said. “That’s why nano tagging is good. In terms of cost, they’re not that expensive. The science is moving so quickly. It’s fascinating what people can learn about birds.”
In addition to documenting migration patterns, the project collects information about the captured birds’ health status. This offers an indication of the condition of the birds’ habitat, a key consideration given ongoing coastal development, particularly in southern Maine.
The tags, produced by the Lotek company, are extremely lightweight and can 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.
O’Brien said each of the 30 birds she plans to tag this summer can be individually identified when their tags send out signals near one of the towers.
“They run the same frequency but each uses a different burst rate,” she said. “It’s like an individual pulse. We record the pulse rate and send in the data.”
Data goes to a central repository managed by Dr. Philip Taylor at Acadia University in Nova Scotia. Taylor is a pioneer in the use of this technology, particularly radio towers used to gather transmitted data.
O’Brien said 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 UMaine and Lindsay Tudor, shorebird biologist for the Maine Department of Inland Fisheries and Wildlife. The project initially focused on Down East Maine and expanded into southern Maine this year.
“We got a grant for tracking sandpipers,” said Holberton, who added the project grew from a similar one that tracked inland birds, like songbirds. “We put transmitters on them last year. There was no way to track [shorebird] movements in the region. We connected the need to track shorebirds with the technology developed to track other birds. This cascaded from doing land-based bird studies into understanding shore bird movements.”
Holberton noted Dr. Taylor’s role in the overall project. “The tower system is part of a huge network,” she said. “Taylor is good at restructuring technology and using it for smaller birds at a much lower cost. The Canadians had already been using the technology on shore birds there.”
Taylor’s data repository is central to the process, Holberton explained.
“We turn on each tag [we use], record it and send the recording to [Taylor’s lab],” she said “They create a library of signature burst rates. Any tower anywhere will recognize that burst rate. The information gets sent to Taylor and redistributed to the particular project it belongs to.”
This 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. One of those organizations is the Biodiversity Research Institute in Gorham. BRI’s Kevin Regan described his group’s role in the Maine project.
“Our team from Biodiversity Research Institute is to capture semipalmated sandpipers using specially designed nets,” Regan said. “Once captured, we fit the birds with an individually numbered metal leg band issued by the U.S. Fish and Wildlife service bird banding laboratory, color bands that indicate the state and capture site, a small green leg flag with a unique alpha numeric code, and a small radio transmitter used by the refuge biologist to track the movement of the bird.”
O’Brien’s team has tagged 19 birds so far, with plans to tag 11 more. “We’ll probably go out in September, when the juveniles have had a chance to grow,” she said.
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.”