Among Narragansett Bay's nesting bird species are egrets -- the great egret, snowy egret and cattle egret -- as well as the glossy ibis. Black-crowned night herons and little blue herons represent the heron bird family, Ardeidae. Narragansett Bay's aquatic environment provides a suitable habitat for wetland birds. Many birds use the Bay's estuaries for nesting sites during the summer. When winter arrives, Rhode Island's cold weather forces most birds to migrate from Narragansett to the southern United States or even South America. The wetland birds of Narragansett dine on fish or vegetation.
Many of the Bay's marine mammals are cetaceans, or animals with blowholes on their dorsal area; the blowhole allows the mammals to breath oxygen before diving underwater. Some of Narragansett's cetaceans are the Atlantic white-sided dolphin, short-beaked common dolphin, sperm whale, harbor porpoise and common minke whale. Narragansett Bay also harbors seal species, such as the gray, harbor, hooded and harp seals. Rhode Island's lone manatee species, the West Indian manatee, dwells in the Bay. Of Rhode Island's 36 marine mammal species, the state considers 11 species endangered.
As an inlet, Narragansett Bay hosts a combination of freshwater and saltwater fish. Most saltwater fish live near the mouth of the Bay near the Atlantic Ocean, while the northernmost reaches of Narragansett are home for freshwater specimens. Narragansett's freshwater population features bluegills, sunfish and pickerel. Some saltwater fish in Narragansett's waters are the dogfish, striped bass and blackfish. Commercial fishing is a major industry in Rhode Island. Because of this, some of the state's native fish are on the "threatened" list. These fish include the American brook lamprey, redbreast sunfish, common shiner and brook trout.
The Bay's vegetation varies on the area's aquatic habitats, which are primarily high or low marshes. Narragansett's saltwater marshes are primarily in the southern region of the Bay and home to tall grasses and algae. One of the saltwater marshes' most common grasses is the smooth cordgrass, which grows up to 6-feet tall. This plant grows in low marsh areas where the Bay's tidal basin frequently floods. Some areas of the Bay's marshes have spike grass, sea lavender, black grass and high-tide bush; these plants grow in the high marsh areas.