Maine Coast Heritage Trust has until December to raise money to preserve a small chain of islands off Harpswell, an effort the trust says is crucial to maintaining some of the last undeveloped, open lands in the state.

The group needs a remaining $400,000 to buy Little Whaleboat, Nate and Tuck islands. The islands are owned by a family that offered to sell the land for a total $1.3 million, according to the trust’s president, Tim Glidden.

The islands must be preserved because they are some of the last undeveloped places in the state that are friendly to visitors, Glidden said, and they are also part of a larger network of islands that is home to a number of sea birds.

“They are undeveloped and they are easy to land on, that combination is uncommon in Casco Bay,” Glidden said, and also have sheltered beaches.

“They are connected at low tide with bars so there is a lot of diversity in a small space,” Glidden said. “It gives a wild feeling, but you are only a few miles from Portland and that’s a special experience.”

Anne Marisic of Maine Beer Company, which donated $50,000 to the campaign, said, “These spaces are really important because of how they are dwindling.”

The islands are also important for nesting sea birds. While data doesn’t exist on how many birds may make homes in these particular islands, a total of 61 islands in the bay are homes for sea birds, which rely on the land to raise young and maintain populations as well as escape predators.

“Seabird nesting islands in Casco Bay provide breeding habitat for a range of colonial nesting seabirds that including rare species such as Arctic terns, roseate terns, as well as more common species including common terns, double-crested cormorants, black guillemots, and common eiders,” Glidden said.

For more information on the preservation project and the funding campaign, go to mcht.org.