Constitution Marsh

Constitution Marsh is a 270-acre (110 ha) fresh water and brackish tidal marsh located between Constitution Island and the eastern shores of the Hudson River in Garrison, New York. Together with 80 acres (32 ha) of bordering woodlands, it forms the National Audubon Society's Constitution Marsh Audubon Center and Wildlife Sanctuary. Part of Hudson Highlands State Park, it is one of five major tidal marshes along the Hudson River. Constitution Marsh is an Audubon Important Bird Area, and has been listed as a New York State Bird Conservation Area since the early 2000s. It is also recognized by the New York State Department of State as both a Significant Coastal Fish and Wildlife Habitat and a Scenic Area of Statewide Significance.

A small creek called Indian Brook flows to the Hudson River through the southern end of the sanctuary; the estuarine environment near the mouth of the creek attracts a wide array of fish, crustaceans, and amphibians, among other animals, some of which are otherwise uncommon in the region.

Over 200 species of both migratory and non-migratory birds have been identified in the marsh. It serves as a wintering ground and stop-over point for migrating waterfowl, which gather in numbers as high as 4,000 in the fall. These waterfowl include American black ducks, wood ducks, and mallards. Constitution Marsh is also used by migrating pied-billed grebes, ospreys, northern harriers, and peregrine falcons; at least 2 and as many as 30 bald eagles can be found there in the winter. Autumn concentrations of swallows once peaked at 100,000, but have dwindled since the mid-1990s. Over 50 different bird species are known to breed within the wildlife sanctuary, including the least bittern, worm-eating warbler, Virginia rail, Louisiana waterthrush, northern cardinal, spotted sandpiper, gray catbird, common yellowthroat, marsh wren, eastern phoebe, swamp sparrow, and willow flycatcher, as well as the wood thrush, which breeds in the forest near the swamp. The marsh was included in bird habitat studies in 1986–1987 and again in 2005. The results revealed that the diversity of breeding bird species is steadily decreasing as the red-winged blackbird becomes dominant.

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