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Loon Program: Tracking Red-throated Loons
Loon Program: Tracking Red-throated Loons

Determining Offshore Use of Diving Birds Using Satellite Tracking: Red-throated Loons

Increasing interest in offshore wind development to meet rising energy demands necessitates research on potentially affected natural resources that will provide regulators, developers, and the public with data that informs permitting and siting processes. Proposed wind energy areas in the mid-Atlantic region overlap with core wintering ranges of multiple marine bird species, including the Red-throated Loon (Gavia stellata). This Arctic-breeding bird is the smallest of the world’s five loon species and large concentrations have been observed wintering off the mid-Atlantic coast.

Lead Investigator: Carrie Gray

Contributing BRI Staff: Carl Anderson, Andrew Gilbert, Wing Goodale, Rick Gray, Michelle Kneeland, Robby Lambert, Chris Persico, Lucas Savoy, Iain Stenhouse, Jeff Tash, and Kate Williams

Project Goals

Project Goals

The U.S. Fish and Wildlife Service designated the Red-throated Loon as a “bird of conservation concern” due to an overall declining population; however, some populations appear to be stable and others have unknown trends. Primary population threats include nest predation, oil spills, contaminant exposure, overfishing of forage fish, and mortality associated with entanglement in fisheries gill nets. Additionally, it has been ranked as a species that is highly sensitive to displacement from foraging areas near offshore wind energy facilities.

In order to assess the effects of disturbance and the potential population impacts of offshore wind development on Red-throated Loons, basic information must be collected on their distribution and behavior, including flight pathways and timing of habitat use, within proposed wind energy areas. BRI is working with multiple collaborators to meet those objectives by determining fine-scale occurrence and local movement patterns of Red-throated Loons in federal waters of the mid-Atlantic U.S. during migration and winter, using platform terminal transmitter satellite tracking tags (PTTs).

Project Components

Project Components

Red-throated Loons are targeted for capture between January and March within Delaware Bay, Chesapeake Bay, and Pamlico Sound, and within 3 to 4 miles offshore in the Atlantic Ocean adjacent to those bays. Individual birds are captured at sea with large handheld dip nets while using established night-lighting techniques. Overall health assessments of birds are conducted by wildlife veterinarians who then surgically implant PTTs before releasing the birds at their capture locations. Satellite transmitters send location data of individuals to orbiting satellites during set periods of the day, which can then be mapped. Tracking individuals will be used to identify high use areas during winter and migratory periods, including important offshore migration corridors and source breeding populations. Additional opportunistic research topics being examined during this study include general health assessment findings, contaminant exposure risk, and genetic profiles of Red-throated Loons wintering on the East Coast.
Researchers use night-lighting techniques to capture birds at sea (left); Scientists apply an identifying band to a Red-throated Loon (right).
Researchers use night-lighting techniques to capture birds at sea (left); Scientists apply an identifying band to a Red-throated Loon (right).
Researchers use night-lighting techniques to capture birds at sea (left); Scientists apply an identifying band to a Red-throated Loon (right).
Project Updates

Project Updates

Capture efforts conducted in 2012, 2013, and 2014 resulted in the deployment of 66 satellite-tagged Red-throated Loons. Tracking results to date have yielded critical and previously unknown information regarding the species’ winter habitat use, migration routes, and breeding locations. Birds typically left the wintering grounds within the first two weeks of April with most following a northward route along the East Coast while utilizing major stopping and staging areas, particularly Nantucket Sound, Gulf of St. Lawrence, and Hudson Bay. Arrival on the breeding grounds typically occurred within the first two weeks of June ranging primarily across Nunavut north to 80 degrees, but also northwestern Greenland, northern Quebec, and as far west as Banks Island, Northwest Territories. Southward fall migrations typically began in late August and tended to follow a more inland route that relied on the southern Great Lakes as a major staging area before arriving back on the wintering ground in late November and early December.

Additional funding provided by the Bureau of Ocean Energy Management for a fourth field season beginning in winter 2015 will extend what was initially a 3-year study, which will serve to strengthen the study by increasing the overall sample size, and testing alternate tagging techniques designed to increase tag life and reduce invasiveness over implanted PTTs.

Project Team

Project Team

Lead Investigator
Carrie Gray, Wildlife Research Biologist

Field Crew Leader
Carl Anderson, Associate Wildlife Biologist

Field Crew
Rick Gray, Associate Wildlife Research Biologist
Robby Lambert, Associate Wildlife Research Biologist
Chris Persico, Associate Wildlife Research Biologist

Contributing BRI Staff
Andrew Gilbert, Data Management Director

Wing Goodale, Deputy Director, Center for Ecology and Conservation Research Director
Lucas Savoy, Waterfowl Program Director
Iain Stenhouse, Senior Science Director, Marine Bird Program Director
Jeff Tash, GIS Analyst
Kate Williams, Wildlife and Renewable Energy Program Director

Project Veterinarians
Scott Ford, Avian Specialty Services

Darryl Heard, University of Florida
Michelle Kneeland, BRI
Glenn Olsen, USGS

Project Coordinators 
Scott Johnston, U.S. Fish and Wildlife Service 
Kirsten Luke, U.S. Fish and Wildlife Service
Caleb Spiegel, U.S. Fish and Wildlife Service


Project Funding and Collaborators

The satellite tracking study was funded primarily by the Bureau of Ocean Energy Management and additional funding was also provided by the Department of Energy and the Bailey Wildlife Foundation.

Our research partners include:

Photo Credits: Header photo: Satellite-tagged Red-throated Loon shortly after release © BRI-Rick Gray; Avian veterinarian Scott Ford and project manager Carrie Gray examine a satellite-tagged Red-throated Loon before it is released in Indian River Bay, DE © BRI-Carl Anderson; Carl Anderson and Rick Gray take notes on the condition of a Red-throated Loon shortly after it was captured in Delaware Bay © BRI-Jonathan Fiely; Night-lighting for Red-throated Loons on Delaware Bay with a 1.5 million candlepower spotlight © BRI-Jonathan Fiely; Rick Gray and Carl Anderson examine the plumage on a Red-throated Loon © BRI-Jonathan Fiely; Michael Chickering releases a satellite-tagged Red-throated Loon near shore in Pamlico Sound © BRI-Jonathan Fiely; Michael Chickering, Carl Anderson, and Jonathan Fiely with a Red-throated Loon captured in Chesapeake Bay © BRI-Jonathan Fiely.
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