Great Gull Island

Great Gull Island is a 17-acre (6.9 ha) island separating Long Island and Block Island sounds, located approximately 0.4 miles (0.6 km) southwest of Little Gull Island. Both islands are located in Suffolk County, New York, and lie roughly midway between Plum Island and Fishers Island.

A major stopover for birds following the Atlantic Flyway, Great Gull Island was the home of large colonies of nesting terns up until the end of the 19th century, when many birds were killed as a result of the millinery trade and the construction of military fortifications on the island. In 1897, Fort Michie was constructed on Great Gull Island to guard the entrance to Long Island Sound. The military base was operational from the Spanish–American War through World War II. It included one of the largest gun installations in the United States, an emplacement for a 16-inch gun on a disappearing carriage.

Great Gull Island was acquired by the American Museum of Natural History on March 31, 1949. It marked the beginning of the Great Gull Island Project, a long-term effort by staff from the museum and other volunteers to restore the island's ecosystem. Gradually, terns began returning to the island to nest, and the population grew into one of the largest colonies in the world for two species of terns.

The dominant faunal feature of the island during the summer months is the active Common Tern (Sterna hirundo) colony spread across the flatter areas of the island that are not taken over by bittersweet (Celastrus) or common reed (Phragmites australis). A tentative estimation of the S. hirundo mating pairs present on the island places their number at 10,000, though this has not been confirmed, due to the inavailability of a complete and authoritative census.

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