The history of the Bird Island lighthouse in Sippican Harbor is on display through late summer, in a new exhibit at the Sippican Historical Society museum on Front Street. The exhibit documents the changes on the five-acre island and the lighthouse, which was built in 1819 and was closed in 1933, though it remains automatically lighted as an aid for navigation. Due to erosion, the land has withered to one acre, said Peter Smith, museum curator. Artifacts in the exhibit include such things as photos, lightkeeper logs, vessel souvenirs, Bird Island china, and garments worn by the light keeper. The exhibit is free and open to the public.