Two juvenile female peregrine falcons captured and released this fall from Monhegan Island are providing wildlife biologists with new information for siting offshore wind-power projects.

Both birds were fitted with satellite transmitters and released on separate days in October before making the flight down the East Coast to Cape Hatteras, N.C., in less than a week. The birds then shot across the water to winter quarters in Cuba and Colombia.

The BioDiversity Research Institute in Gorham is studying the migratory habits of falcons, saw-whet owls and eider ducks as part of an unprecedented international network of research aimed at understanding bird migration in the region and how it might be affected by offshore wind-power projects now under development.

Researchers are scrambling to figure out the flight paths of different migratory bird species to help guide siting decisions for the 400-foot-high wind turbines that could soon sprout in the Gulf of Maine.

The University of Maine has identified three offshore test sites for floating turbines that are due to start operating next year. With Interior Secretary Ken Salazar’s announcement last month of plans to speed up the siting of offshore wind projects in the Atlantic, trying to keep the potentially lethal turbines away from migration routes has gained new urgency for biologists.

“BRI is really helping to fill in some of the pieces of the puzzle,” said Rebecca Holberton, a University of Maine professor who is leading the Gulf of Maine’s Northeast Regional Migration Monitoring Network.

The network also includes the U.S. Fish and Wildlife Service, the Maine Department of Inland Fisheries and Wildlife, Maine Audubon, Nova Scotia’s Acadia University and the National Audubon Society’s Seabird Restoration Program.

The institute’s saw-whet research was led by wildlife biologist Kate Williams, who found the species last year in an unexpected spot — Isle au Haut off Penobscot Bay.

This year, Williams set up eight research stations from Lubec to Cape Elizabeth to count saw-whets — robin-sized owls that weigh about a fifth of a pound — as they moved from Canada and northern Maine to their wintering grounds in North Carolina, northern Georgia and Alabama.

For the first time, biologists documented that the owls were traveling over the ocean at night, rather than over land as previously suspected.

“This is one of the amazing scientific moments of discovering something,” said Williams.

The falcon research took place on Monhegan Island, where biologists counted birds during four weeks of the fall migration as the speedy raptors made their way through Maine from points north to wintering grounds as far south as Argentina. More than 800 birds of prey, three-quarters of them falcons, were counted. The falcons included peregrines, merlins and kestrels.

Chris DeSorbo, BRI raptor program director, said the falcons were following their food source — other birds — as they moved south. The researchers caught 25 of the falcons, and measured, sampled and banded them. Two were fitted with satellite transmitters that are too heavy for other species.

They discovered the birds flew almost identical paths, sometimes spending more than a week at a time over open ocean. Together, the two birds traveled more than 6,400 miles.

DeSorbo said he will be following the birds over the next year and analyzing the data to find out at what altitudes they fly, and whether they started out from the cliffs of Greenland, as DeSorbo suspects.

Maine’s eider duck population is also being studied. Maine and Alaska are home to the largest eider breeding grounds in North America. Maine’s estimated population of 25,000 eiders congregate in huge groups up to a quarter mile from the coast, where they feast on a plentiful supply of blue mussels.

Early results of research on Maine’s eider duck migrations suggests that offshore wind power may have little impact on the birds.

BRI wildlife research biologist Lucas Savoy said experts suspected that the eiders flew out to sea at night to float far away from crashing waves and rocks as they slept. But nobody really knew how the birds moved about.

After fitting four eider ducks with satellite transmitters, their secrets were finally revealed.

“They seem to be fairly stationary,” said Savoy.

Holberton said a huge swath of the Maine coastline remains uncharted territory as far as understanding bird migrations is concerned. In the past few years, researchers have learned more through radar, bird counting and banding. They are also using less conventional techniques. Ultra-sensitive microphones are recording the night flights of songbirds, which reach altitudes up to 2,000 feet over the water in fair conditions, far above the reach of wind turbines.

But when visibility is poor, the birds fly at much lower altitudes, under 500 feet.

“Most of the birds are island hopping and that is why wind development in shallow water and right along the coast in my opinion poses big issues,” said Holberton.

Staff Writer Beth Quimby can be contacted at 791-6363 or at:

bquimby@pressherald.com