WINDHAM, Maine — The common loon’s haunting wail that pierced the dusk on Massachusetts lakes disappeared long ago.

Today, the birds number fewer than 50 pairs in the Bay State and conservationists are hoping to rebuild their population, starting with a handful of chicks from Maine and New York.

The Restore the Call program at the Biodiversity Research Institute in Portland plans to move 10 chicks to an area south of Boston this summer. David Evers, the institute’s executive director, said restoring an animal population starts out small but he is optimistic.

Loons once lived throughout Massachusetts. Hunting and habitat loss contributed to their decline and they were wiped out by 1898, the last eggs plucked near a lake south of Boston. They began returning in the 1970s, but the state still only has 45 breeding pairs.

“All we need to do is establish one pair,” Evers said. “Once that one pair is established and once that pair produces young, and those young come back, and they start to establish territories, then you’ve got some brooding that can start from that little seed.”

However, common loons can be slow to recover because they don’t breed until they are several years old.

“Loons depend on high quality habitat without certain types of disturbance,” said Danielle D’Auria, a wildlife biologist with Maine Inland Fisheries and Wildlife.

The bird’s range has shrunk throughout the U.S. It has disappeared in Oregon and southern Michigan and parts of Idaho, Montana and Washington. It is a threatened species in New Hampshire, where last year biologists for the Loon Preservation Committee recorded 234 loon chicks hatched and 26 percent of them did not survive.

In all, researchers count about 14,000 loon pairs in the country.

And while their population remains strong in Canada, where they are a national symbol, the birds face threats of mercury and lead pollution there as they do in the United States.

Maine Audubon, which is helping with the relocation project, says Maine has at least 2,000 pairs of loons and New York has about 1,000. The Institute has undertaken similar projects in Minnesota and plans to add Wyoming to the program next year. A $6.5 million grant from the Ricketts Conservation Foundation funds the loon relocation efforts.

The Institute also relocated seven chicks from New York’s Adirondack area to Massachusetts last year.

Most of the few dozen loons in Massachusetts live near the Quabbin and Wachusetts reservoirs in the central part of the state. The chicks will be relocated to an area near where the last eggs were believed taken before the birds disappeared from the state.

Maine has the largest common loon population in the eastern U.S. and the birds are loved in the state. Bird enthusiasts participate in Maine Audubon’s “loon count” every year.

Susan Gallo, wildlife biologist for Maine Audubon, said the group is working with the birders, some of whom haven’t embraced the idea of Maine loons moving out of state.

“Loons are near and dear to people’s hearts in Maine,” she said. “Anything we can do to get the loons to nest in new places, I think, is a benefit to loons.”