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News The terns approve Bird Island

Rare terns return to Bird Island for nesting after restoration of the island is completed.
  • Division of Fisheries and Wildlife
Tern studies on Bird Island

Last summer (see MassWildlife monthly July 2017), we reported on the completion of the restoration efforts for Bird Island off the coast of Marion, Massachusetts. Since then, the final touches were completed on the island, and the terns seem to approve.

Two-acre Bird Island is home to about 3,500 pairs of nesting terns. Terns are small, fish-eating seabirds that nest on the ground. The species nesting on Bird Island are the federally endangered roseate tern (Sterna dougallii) and the state-listed special concern common tern (Sterna hirundo). These terns are migratory, arriving in Massachusetts in April to nest and leaving in September for their wintering grounds on the north and east coasts of South America.  Bird Island is one of only three major roseate tern nesting sites in North America. As the second largest nesting colony—supporting about 25% of the entire North American population—Bird Island is a critical site to protect and restore.

The island’s historic lighthouse, built in 1819, was nearly surrounded by a seawall dating to the mid-1800s. Over time, however, storms and sea level rise took their toll on the seawall and the nesting habitat. The seawall had deteriorated and only half of the area inside it was high enough above the tide levels to support nesting terns. During the deterioration of Bird Island the past decades, some terns emigrated to other sites—such as Ram Island, Mattapoisett and Penikese Island, Gosnold. The terns that remained on Bird Island were increasingly crowded into the ever-shrinking area.

Over the winters of 2015–2016 and 2016–2017, project partners rebuilt the seawall higher and wider to combat storms and sea level rise. During the springs of 2017 and 2018, the interior of the island was nourished with sand and gravel to raise the elevation and improve the nesting substrate. Native coastal perennials such as seaside goldenrod and American beachgrass were planted across the island to provide cover for nests and chicks.

The terns have taken readily to the new material and, with double the area now available, there is space for the population to grow. Additionally, the new seawall, built to withstand at least 50 years of sea-level rise, will help to slow erosion and secure the site for the terns well into the future.

Funding for the restoration was provided by the Commonwealth of Massachusetts, the U.S. Army Corps of Engineers, and the New Bedford Harbor Trustee Council, with support from the Town of Marion.

Division of Fisheries and Wildlife 

MassWildlife is responsible for the conservation of freshwater fish and wildlife in the Commonwealth, including endangered plants and animals. MassWildlife restores, protects, and manages land for wildlife to thrive and for people to enjoy.