Located along the Atlantic Flyway, the refuge is of vital stopover significance to waterfowl, shorebirds, and songbirds during migratory periods.

The ecology of the island, however, is not in its original state, due to earlier draining of Great Marsh by parallel channels and destabilization of the dunes by overuse.

In the waters, the chemical pollution of the Merrimack River and the damming of its stream at a number of locations totally changed the character of the fish and the bird species that fed on them.

Even today coastal currents from the Merrimack in flood deposit unacceptable levels of debris on the beach, which are typically removed in public campaigns.

More recently heavy equipment was used to replace the parallel channels with unconnected pools in some places, recreating the original marsh.

This article incorporates public domain material from websites or documents of the United States Fish and Wildlife Service.