Great Diamond Island in Casco Bay has nearly tripled its year-round population over the last decade, while most of Maine’s smaller islands have lost residents. While increase in real numbers is relatively small, according to the latest U.S. Census Bureau figures, the steady growth of Great Diamond’s population puts it on par with Cliff Island, Monhegan and Isle au Haut, while surpassing Frenchboro and Matinicus, which have seen their populations dwindle during the past ten years.

While the Casco Bay and Penobscot Bay islands have had their year-round numbers hold steady or register modest increases, the summer population on all Maine islands has grown at a much greater rate. As suburban real estate values (and incomes), grew throughout the 1980s and 90s, mainlanders found it easy to obtain financing for vacation or retirement properties. The subsequent boom in seasonal island and coastal real estate has not cooled, in spite of state and local anti-sprawl regulation and shorefront zoning.

This process of island “gentrification” has put increasing pressure on the natural resources, infrastructure and services. It has particularly affected young families. Most islanders are currently at the limit of their childbearing years, or beyond them. High property values often prevent islanders from purchasing or renting homes in the communities in which they were raised. Young adults often migrate to the mainland to raise families and return, if at all, during late middle age. Many year-round islanders are elderly. New residents are often retirees.

In addition to Frenchboro, the downeast islands of Swan’s and Cranberry Isles are also losing resident population, while Isle au Haut has increased by 70 percent. In actual numbers, population changes are relatively small, but can be quite significant for small islands. Even a few families with children who relocate off-island can change the dynamics of community life. Great Cranberry and Matinicus have empty schools at present, although both communities have voted to keep their schools open in the event of new families moving offshore.

Even census figures can be misleading. Cliff Island residents claim their actual full-year population is closer to 60 than the 87 reported by the Census, while Matinicus has seen winter resident numbers of 30 or less in recent years.