The tidal marsh, coves, creeks and ridges of Glenn Martin National Wildlife Refuge provide an important rest area and winter home for thousands of migratory waterfowl and nesting habitat for a variety of wildlife that change with the seasons.
Winter residents on the refuge include black ducks, pintail, mergansers, long-tailed ducks, scoters, bufflehead, Canada geese, and tundra swans. During spring and summer, the salt marsh grasses, abundant insects, and underwater vegetation attract black ducks, mallards, gadwall, and green-winged teal to nest on the refuge. Gulls, terns, black skimmers, oystercatchers, and willets nest and feed along the marsh grasses, mud flats, and sand bars. The wooded ridges provide nest sites for several water birds. Ten different species, including herons, egrets, and glossy ibis have been seen in rookeries on the refuge. Rookeries are groups or colonies of birds that nest together. Martin NWR supports the largest colony of brown pelicans in the Maryland portion of the Chesapeake Bay.
A small population of red fox, muskrat, mink, otter, voles, northern diamondback terrapin, and various nonpoisonous water snakes also live in the marsh areas. Clapper rails, sea-side sparrows, and marsh wrens also depend on the protected refuge habitat. Peregrine falcons have been nesting on the refuge every year since the first peregrine nesting tower was installed in 1984. The marsh and estuary are important in the production of marine species such as crabs and oysters that help form the food chain.