Desmond-Fish Library Logo

Back one level
Books & Reading


"A Year on Constitution Marsh Sanctuary"
by Jim Rod

Constitution Marsh Sanctuary
Rt. 9D, Garrison, New York 10524

Located directly across the Hudson River from West Point, and tucked in behind historic Constitution Island on the east shore, Constitution marsh is a superb example of a Hudson River tidal wetland. The 270 acre marsh was purchased on 1969 by Lila Acheson and Dewitt Wallace and Laurance Rockefeller, and turned over to the National Audubon Society to manage as a public wildlife sanctuary the following year. For decades marshes were seen as wastelands, useful only to the extent that they could be dredged, filled, built upon or converted to something else. Many thousands of acres of Hudson River marshlands have disappeared; converted to building sites, marinas or garbage dumps, and only four sizable marshes in addition to Constitution marsh remain on the 154 tidal portion of the river. These four are now protected as part of a state/federal Hudson River Sanctuary program, for the message is finally getting through that tidal marshes are probably the richest and most biologically productive ecosystems on earth.

Constitution Marsh is unique among Hudson River tidal wetlands because it lies at that point where the salt front is most active. The marsh therefore ranges from primarily freshwater to brackish to occasionally quite saline, depending upon the season and the amount of snowmelt runoff, storm events and drought. A year-long study of fishes of Constitution Marsh funded by the Hudson River Foundation demonstrated the diversity such conditions can produce: 35 species representing 18 families were collected. On one occasion a single seine haul produced bluefish, brown trout, yellow perch, bluegill, killifish, mummichogs, and fourspine sticklebacks.

Constitution Marsh is further unique because adjacent to Foundry Cove is the world's most heavily cadmium-polluted site. Marathon Battery operated a factory there for 27 years and saw Foundry Cove marsh and the nearby Hudson River as convenient repositories for wastes containing scores of tons of cadmium, nickel and cobalt. The entire area is now an EPA Superfund Study site. Intensive biota sampling during the field study phase of the Superfund investigation in 1984 produced the world-record snapping turtle from Constitution Marsh, and Bob Boyle has several times collected the rare giant stonefly Allonarcys biloba at sea level in Indian Brook, a trout stream which enters the tidal flat at the south end of Constitution Marsh.

An 1837 attempt by Henry Warner to farm wild rice in the marsh failed, but left several miles of interconnecting channels, making Constitution Marsh the most accessible of any on the Hudson River. A full-time resident manager employed by the National Audubon Society conducts guided tours of the marsh, and offers a variety of other on- and off-sanctuary educational activities. A nature trail terminating in a 300-foot boardwalk into Constitution Marsh is open to the public year around.



October is a month of great change in Constitution Marsh. Nearly all of the hundreds of resident snapping turtles have hibernated; burrowed deep into the mud where they will absorb their reduced winter oxygen requirements through their rectums. Blue crabs, bluefish and needlefish have retreated down the Hudson. Small herring are still present in the early month but gone by the middle. Except for a few straggling tree swallows, the early September night-roosting flocks of 100,000 swallows have gone south, and have been replaced by smaller but still impressive flocks of red-winged blackbirds, grackles, starlings and cowbirds which settle noisily into the cattails just before sunset. Lingering marsh wrens and swamp sparrows work silently through the marsh vegetation, gleaning the last of the spiders and small insects and occasionally whispering snatches of their vibrant summer songs. Chickadees, downy woodpeckers and late-migrating warblers often join them. September Red dragonflies are still around and warm days can bring incredible midge hatches. Southbound Monarch butterflies drift over the marsh on lazy wings. Shortening daylengths mean less chlorophyll production, and cattails and hardwoods which entered October green and vigorous have faded into their fall colors by mid-month. Maples and dogwoods provide the brilliant splashes of color in the surrounding Hudson Highlands, but Constitution Marsh cattail colors more closely resemble some of the oaks or the sere yellows of American beech leaves. Scattered swamp rose mallow leaves are brighter yellow. Though subdued, autumn colors in the marsh can be spectacular, especially when accented by the gleaming white of a late egret or a flock of snow geese. A few ospreys linger into October and migrating Marsh hawks dip low as they course over the cattails, but October is wood duck month in Constitution Marsh. Flocks of 500, most of them locally produced, may forsake nearly all other food and turn to fat- and protein-rich acorns, climbing through oak limbs like avian squirrels to harvest them. The acorns are swallowed whole to be ground up in powerful gizzards, and some years the nut crop is so heavy that oak leaves overhanging the east shore are submerged at high tide and stripped in days by hungry wood ducks. These beautiful birds have tender toes, though, and frosty nights that hint of November will send them south by the end of the month.


November is usually the month of the Grand Passage in the Hudson Valley and is the month when Constitution Marsh Sanctuary fulfills one of its most important roles as a safe migratory stopover for thousands of waterfowl. Bitter Arctic winds sweeping across the tundra and into the Boreal forests and breeding grounds of the Canadian Provinces which contribute to the Atlantic Flyway, and the steady southward advance of the 35-degree isotherm pushes the ducks and geese before it. Migrating mallards moving before a storm may stream down the Hudson all day long; flocks of several hundred spaced only minutes apart. Some of these birds have been in the air for 24 hours, and weary bunches of them break away from the main flight and drop into Constitution marsh. They may stay for a night or for several weeks, to be joined by lesser numbers of pintails, widgeon, gadwalls and mergansers. Black ducks also arrive to swell the November numbers, and by the end of the month may outnumber mallards three-to-one. This is encouraging, for black ducks have been declining steadily for thirty years. Acid rain, poor wintering habitat or overhunting may be responsible, but whatever the reason, those coming down the Hudson seem to like Constitution Marsh. They will stay in the marsh until forced out by December ice.


The Hudson River, along with Constitution Marsh, usually begins to freeze in December, and the ice brings the eagles. As many as half a dozen bald eagles use Iona island, eight miles down the Hudson, as a winter night roost, and during the day they often fly upriver to Constitution Marsh to feed on dead fish frozen into the ice. They are joined by the black-backed, herring and ring-billed gulls, and usually the frozen marsh has its complement of crows. Muskrat lodges in the marsh which are going to be used for winter quarters have reached their maximum size, and they must be solidly built to withstand the grinding action of ice shifting three feet up and down with each tide change. Muskrats don't hibernate, and spend a good share of their time foraging beneath the ice for cattail, pickerelweed, arrow arum and other tubers which they dig out of the mud. They may vary their winter diets with bullheads and other fish which congregate in the openings of their lodge plunge-holes, or they may dig hibernating frogs out of the mud. Red-tailed hawks frequently soar over the marsh in search of small mammals, and fresh snow on the marsh ice sometimes reveals tracks of foxes and coyotes which have crossed it to reach Constitution Island. Now that most marsh life is operating beneath the ice or overhead, the dense cattails stands are no longer needed for surface shelter and the elements can take over. Early winter winds can make the cattails in the marsh look the way Willa Cather described the tallgrass prairie, as though the country were running, but the running stops as snows accumulate and the prevailing winds soon push the brittle cattail stalks over on their sides. This begins the process of conversion of these tons of cattails and other marsh plants into detritus; the fuel for the food chain in the marsh.


The new calendar year in Constitution Marsh usually finds it thoroughly frozen. The black ducks and mallards that managed to keep a few December potholes open have moved out into the unfrozen areas of the Hudson to join several thousand canvasbacks, scaup and ring-necked ducks. Insulating snow on the ice cover, and constantly running tidal waters beneath keep the marsh bottom from freezing, but no matter how severe the winter, the ice on the channels is never to be trusted. It never freezes solidly, but in layers, and even when supported by high water beneath can be treacherous for a person afoot. Snowshoes offer some advantage by distributing weight over a larger area, but winter-bound marsh explorations are best conducted among the cattail stands where the footing is more secure. Even there the marsh explorer often drops into muskrat-cut channels or slides off a clump of tubers into the muck beside it. Much of that can be exhausting work and the winter visitor is well advised to confine strolls to the boardwalk. From there can be obtained fine views of the marsh and of the encircling Hudson Highlands; from the bare expanse of Storm King around the circle to Bull Hill, rising above Cold Spring; leafless in January with the gray monotony broken here and there by fingers of hemlocks and other conifers reaching up the mountains.


February usually brings our coldest nights, and often finds screech owls using empty wood duck nesting boxes for winter roosts during the day. Apparently oblivious to the cold, great horned owls are already sitting on eggs, and their mournful territorial hoots echo through the iron-bound hardwood forest nights near the marsh. For all their cold, February days can be bright and sunny, and such days may find chickadees and other small forest birds well out among the cattails searching for egg clusters and hibernating insects. The jet-black of the curious crows counterpoints the snowy marsh and they may sometimes gang up to chase an eagle away from a titbit frozen into the ice. Gulls gather to peck at fish remains in the ice and small flocks of mallards wheel in from the River to look in vain for open water. Resident Canada geese lift off from the Hudson and pass over the marsh on their way to the Dutchess County cornfields and late in the month the local red-tailed hawks ride the weak thermals over the marsh as they begin their courtship flights. Voles, mice, shrews and occasionally ermine - white-coated weasels - tunnel through the snow under the bent-over cattail clumps and occasionally a muskrat lodge is opened by a hungry or curious fox or coyote. My only record for a river otter occurred one February when I followed its alternating tracks and belly-slide marks in the snow to the edge of the marsh. Neither otters nor beavers like tidal marsh.


Things begin to happen in March. At some point in the month the ice begins to go out of Constitution Marsh, and as soon as that happens, one of the most important events in the life of the marsh occurs: the dead cattails fall into the water. By March the brittle dead stalks have been thoroughly broken up by the wind, snow and ice, and when they fall into the water they quickly become soaked and begin to fall apart. They sink to the bottom where decomposing bacteria and other tiny organisms such as isopods go to work on them, releasing the nutrients they contain. Copepods, amphipods and many other small creatures eat this detrital material and themselves become food for larger fish and we finally complete the complex marsh food chain when we sit down to a dinner of striped bass or bluefish. From 60 to 80 percent of all finfish and shellfish depend upon estuarine marshes at some crucial stage of their life cycle.


Most people don't notice what's going on with the dead cattails in Marsh, but it's hard to miss the spring waterfowl migration. As soon as the ice is gone the ducks are already in; ruddy ducks and buffleheads, more mallards and blacks, hooded mergansers and blue- and green-winged teal, and here are the wood ducks back again. They came in last night with the great blue herons. And the red-winged blackbirds, just the males, here two weeks ahead of the females, each one on a song perch and arching its epaulets at its neighbor. Kingfishers appear from nowhere and mount a patient watch from dead limbs overhanging the tide channels. Their minds are on killifish and spottail shiners. The first white suckers are moving into Indian Brook under cover of darkness, getting ready for the ritual of spawning and look, over here, where the ground is still frozen: how did the skunk cabbage get so tall and we didn't notice? There's too much to see in March. The eastern phoebes and bluebirds are back, and that means the coltsfoot will be blooming soon. And there goes a garter snake, the first one this year. Did you hear that flock of geese going over last night? Muskrats are swimming on the surface for the first time in three months and tree swallows are already prospecting for nesting holes in dead tree stubs. Where did winter go? Let's go down to the marsh and see if the least bitterns are back yet. It's probably too early but we can sit on the boardwalk and listen to the red-wings and watch the ducks and we may see snow geese heading north up high over the river. Who knows? Let's take our lunch and stay all day. There's too much to see in March.