Natural History of the Hudson River

hudson river

The Hudson River begins in Lake Tear of the Clouds on the southwest side of Mount Marcy, New York’s highest peak. The Hudson River is 315 miles long . The deepest point is World’s End near West Point which is 216 feet deep. It’s widest point is at Haverstraw where it is three and one half miles wide.

From Troy south to the river’s mouth in New York harbor, the Hudson takes on the properties of the ocean as well as a river. As the tide rises in the Atlantic, salt water is pushed upriver. Although the salt travels only as far as Newburgh in the dry season and Tappan Zee during periods of heavier precipitation (fresh water runoff pushes the salt front down river), the entire length of the river is affected by tides. The highest tide on the river (4.7 feet) actually occurs at Troy, its northernmost point, while West Point, in the Hudson Highlands, sees only a 2.7 foot rise.

Like the Norwegian fjords, glaciers played a role in carving and shaping the Hudson. In several places, such as the Palisades on the New York / New Jersey border, the river is bordered by cliffs that plunge almost directly into the water – a main characteristic of fjords.

The Habitats and Wildlife of the Hudson

The Hudson is not simply a static body of water in which organisms are either land dwellers or entirely aquatic. The tides divide the river’s banks into several wetland communities, each with a unique mix of plants and wildlife.


Most numerous, and perhaps most important among the Hudson’s plants are the phytoplankton: microscopic plants that provide food for many species. Beneath the low tide mark, in the subtidal zone, grow submerged aquatic plants. Although their decreased access to sunlight makes them less photosynthetically productive than plants in upper tidal zones, they are and important food source for waterfowl and fish, as well as a habitat for aquatic insects.

The emergent (above water) plants of the Hudson comprise much of the marsh and estuary areas found on its banks. Marsh plants are perhaps the most productive denizens of the Hudson: nutrients swept into marsh areas by currents are stored in the plants, which provide food and shelter for birds, fish, and invertebrates. As the plants die and fall into the water in the winter, the nutrients are recycled.


The spineless creatures of the Hudson are widely varied, ranging from the luminescent and seemingly shapeless comb jelly to dragonfly larva to the more familiar crabs and lobsters of the salty lower Hudson. Like plants, the river’s invertebrates can be classified according to their habitats. The benthic organisms, such as aquatic worms, crabs, and mollusks are found in the soil and at the river’s bottom. The larva of aquatic insects are also found in this zone, particularly in cooler, shallower, faster moving water. Somewhat above the benthic zone is the water column, where jellyfish, zooplankton (single-celled animals) and most fish are found.


Although industrial and agricultural pollution has and continues to plague the Hudson, fish populations remain strong and diverse. In 1995 about 206 species of fish were recorded. Some are permanent dwellers in the river while others like the Shad are ocean dwellers who return to the river to spawn. Estuaries such as Constitution Marsh act as nurseries for many Hudson River fish.Fish common to the Hudson River which are bottom dwellers (benthic) include Sturgeon, Catfish, Flounder, Hogchokers and eels. Fish that inhabit the open water (nektonic) include river herring, basses, bluefish, sunfish, carp killfish and minnows.

In 1994 the New York State Department of Health advised that women and children should eat no fish from the Hudson River because of the high levels of PCB’s found in fish living in the Hudson.

Amphibians and Reptiles

Amphibians in the Hudson River Valley include frogs, toads and salamanders. Reptiles include snapping and painted turtles and more rarely the diamondback terrapin. Snakes include water snakes and garter snakes which will eat fish.


Geese and swans, surface feeding ducks such as mallards, black ducks and wood ducks are common on the Hudson River. Also seen are diving ducks such as scoups, buffleheads, canvasbacks and mergansers. Common shorebirds include killdeer, spotted sandpipers, least sandpipers, greater yellowlegs, snowy egrets, least bitterns, green herons and great blue herons. Perching birds seen in the marshes include marsh wrens, red-winded blackbirds, swamp swallows and yellow warblers. Gulls include herring gulls and great black-backed gulls.Raptors include bald eagles and osprey.


Mammals found along the shores of the Hudson include the white-footed mouse, the meadow mole, the Norway rat, the short-tailed shrew, the muskrat, the river otter and the mink.

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