At around 2:30 Friday afternoon, Helen Hays was watching the third and final load of lumber being lowered off a CH-47G Chinook helicopter onto a spot at the western end of Great Gull Island, the culmination of a unique mission by the Connecticut Army National Guard.

"It's very exciting," said Hays, speaking by cellphone from the 17-acre bird sanctuary located about 7 miles offshore in Long Island Sound, where she has been manager since 1968. "It went very quick. It was very well organized."

At the request of the U.S. Fish & Wildlife Service, the National Guard agreed to airlift 28,000 pounds of pressure-treated 2-by-12-inch and 2-by-4-inch lumber from Groton-New London Airport to the island, owned by the American Museum of Natural History. The island is a "supercolony" for federally endangered roseate terns and common terns, providing nesting areas for more than 10,000 pairs. Volunteer carpenters will use the lumber to build hillside terraces that will serve as new nesting areas for the terns and will also build about 20 bird blinds to replace those destroyed by Superstorm Sandy in 2012.

Suzanne Paton, fish and wildlife biologist with the Fish & Wildlife Service, said about $60,000 in grant funds was used to purchase the lumber and pay the National Guard for the fuel used in the airlift. Those funds were supplemented with $10,000 from Connecticut Sea Grant, located at the Avery Point campus of the University of Connecticut in Groton.

The airlift was originally scheduled for last Tuesday but had to be postponed because of high winds and additional paperwork requirements.

"We have a little bit of time to get the supplies in there where we won't be disturbing the birds," said Paton, adding that the terns are expected to start arriving during the first full week of May.

Lt. Col. Mark Strout said the National Guard unit has done missions for other federal agencies such as the Coast Guard, but this was the first time it was asked to help the Fish & Wildlife Service. Strout added that he was enthusiastic about Friday's airlift both because it would benefit a critical nesting area for endangered birds and because of his fondness for the museum that owns the sanctuary. He said he visits the New York City institution at least three times a year.

"And this is good training for us, because these are nonstandard-sized loads," he said as crews ratcheted cargo straps tight and fixed slings around the loads in preparation for the airlift.

Chief Warrant Officer 4 Matthew McCullough, one of two pilots aboard the helicopter, said the National Guard unit has conducted many airlifts, carrying tractors, armored vehicles and other equipment and supplies to a number of locations, including Afghanistan last September. "We do tons of this kind of thing overseas," he said.

On Great Gull Island, six volunteers and Hays awaited the arrival of the lumber, which was offloaded in two locations. Because the dock on the island was destroyed in Superstorm Sandy, the airlift was the only practical means of getting the lumber there.

Hays said nine carpenters, including several from Electric Boat recruited by New London resident Bud Bray, have agreed to volunteer their services on the island May 3 to build the terraces and blinds.

"We've got a good crew," she said.

j.benson@theday.com