Northeast Coastal Areas Study
Significant Coastal Habitats
Site 11 (NY)
I. SITE NAME: Shelter Island - Harbor Bays Complex
II. LOCATION: This habitat complex of lands and waters is located between the two eastern forks of Long Island, and includes portions of Shelter Island, Shelter Island Sound, Sag Harbor Bay, Northwest Harbor and Gardiners Bay and a narrow section of coastline along the bay shoreline of the South Fork in the vicinity of Sag Harbor.
TOWNS: Shelter Island, Southampton, East
STATE: New York
USGS 7.5 MIN QUADS: Sag Harbor, NY 40072-83; Gardiners Island West, NY 41072-12; Greenport, NY 41072-13
USGS 30x60 MIN QUADS: Long Island, East 40072-E1; New Haven 41072-A1
III. GENERAL BOUNDARY: There are three principal habitat units within this complex: 1) Shelter Island; 2) Open Bay Waters; and 3) South Fork Wetlands and Beaches. The general outline of this complex is delineated on the accompanying map and includes the entire southeastern peninsula of Shelter Island and the long narrow peninsula immediately north of it (Ram Island and Little Ram Island) as well as the intervening waters of Coecles Inlet. South of Shelter Island, the boundary encloses the waters of eastern Shelter Island Sound and Sag Harbor Bay and an area of land to the east known as Barcelona Neck and the adjacent marshes of Northwest Creek. From there the boundary extends northwards along the eastern shoreline of Northwest Harbor, enclosing the areas of Alewife and Scoy Ponds, Cedar Pond and Cedar Point, and then cuts northwestward across a section of Gardiners Bay before connecting with Reel Point on Shelter Island. The approximate linear dimensions of this complex are 8 miles (13 km) long in a northwest-southeast direction and 3 miles (5 km) wide in a southwest-northeast direction.
IV. OWNERSHIP/PROTECTED STATUS: Ownership over this complex is a mixed pattern of public waters and lands (mostly County), The Nature Conservancy preserve lands and private lands.
V. GENERAL HABITAT DESCRIPTION: The large peninsular area of Shelter Island is included entirely within the Mashomack Preserve and contains some of the finest examples of undisturbed coastal ecosystems in the region. This area contains a large diversity of habitats from mature deciduous forest and an extensive system of freshwater and brackish wetlands to coastal beaches, dunes and bluffs. Deciduous forests are particularly diverse on Shelter Island, and are primarily dominated by oaks, of which scarlet, red, black and chestnut oaks (Quercus coccinea, Q. rubra, Q. velutina, Q. prinus) are the most characteristic. The ground layer is dominated by dwarf heaths, mostly black huckleberry (Gaylussacia baccata) and blueberries (Vaccinium vacillans). Sand and pebble beaches and dunes in the area are often sparsely vegetated closest to the water and increasingly vegetated away from the water with such characteristic species as beachgrass (Ammophila breviligulata), seaside goldenrod (Solidago sempervirens) and beach pea (Lathyrus japonicus). Freshwater wetlands include shrub swamps of sweet pepperbush (Clethra alnifolia), swamp azalea (Rhododendron viscosum) and highbush blueberry (Vaccinium atrococcum), white pine (Pinus strobus) - red maple (Acer rubrum) swamps, and freshwater marshes of diverse floristic composition, with many species of ferns, grasses, sedges and herbs.
The embayed areas of Sag Harbor Bay and Northwest Harbor, as well as the portions of Shelter Island Sound and Gardiners Bay included within the boundary, are broad expanses of moderately shallow water, ranging from 6 to 20 feet (2-6 m) in depth, and bordered by mostly undeveloped lands and tidal marshes. Mean tidal range in this area is approximately 2.5 feet (0.76 m). The marshes at Northwest Creek display classic marsh vegetation zonation, with cordgrasses (Spartina alterniflora and S. patens), groundsel-bush (Baccharis halimifolia) and marsh elder (Iva frutescens) grading into oak (Quercus spp.) - pitch pine (Pinus rigida) forests. Alewife and Scoy Pond wetlands on the South Fork shore consist of a network of freshwater and brackish ponds, wetlands, kettles and creeks with a diverse assemblage of swamps, marshes and aquatic vegetation.
VI. SIGNIFICANCE/UNIQUENESS OF AREA: This area, particularly the eastern section of Shelter Island, contains one of the highest nesting densities (mostly on natural snags) and numbers of osprey (Pandion haliaetus) in the region, second only to Gardiners Island; it is likely that this population will continue to expand under the present environmental conditions. The sand beaches of Mashomack Preserve, Cedar Point and others along the South Fork shoreline are regionally important, though seasonally variable, nesting beaches for piping plover (Charadrius melodus), a U.S. Threatened species, and least tern (Sterna antillarum). Sea-beach knotweed (Polygonum glaucum), a regionally rare plant, also occurs on beaches in this general area. The tidal marshes and freshwater wetlands are used extensively as feeding areas for colonial wading birds and wintering waterfowl, and American black ducks (Anas rubripes) nest here. The open bay waters and tidal marshes along the shoreline support large numbers of wintering waterfowl of regional significance, including common loon (Gavia immer), American black duck, mallard (Anas platyrhynchos), Canada goose (Branta canadensis), greater and lesser scaup (Aythya marila and A. affinis, respectively), common goldeneye (Bucephala clangula), red-breasted merganser (Mergus serrator), bufflehead (Bucephala albeola), oldsquaw (Clangula hyemalis) and canvasback (Aythya valisineria).
Northern diamondback terrapins (Malaclemys t. terrapin) feed and nest in the tidal marshes and sandy creek banks throughout the area, particularly around Coecles Harbor. Recent evidence indicates that the waters and bay bottoms of the Peconic Bays, Gardiners Bay and other bodies of water in this area may serve as significant summer feeding and nursery habitat for juvenile Kemp's ridley (Lepidochelys kempii), a U.S. Endangered species and one of the rarest sea turtle species. Harbor seals (Phoca vitulina) use several rock areas in Sag Harbor Bay and Northwest Harbor as haulouts during winter and early spring, often in fairly large concentrations. The harbor areas and bays are also productive habitats for finfish and shellfish, and support a regionally significant commercial shellfishery for bay scallop (Aequipecten irradians) and, to a lesser extent, American oyster (Crassostrea virginica). These waters serve as important nursery and feeding areas for weakfish (Cynoscion regalis), winter flounder (Pseudopleuronectes americanus) and scup (Stenotomus chrysops). Scoy and Alewife Ponds and their associated stream system are one of the few alewife (Alosa pseudoharengus) spawning areas on Long Island.
In addition to its significant fish and wildlife populations, this area, particularly Shelter Island, contains forests and other vegetation types that are both unusual in their composition and associations as well as being relatively undisturbed and well-developed. Examples include a nutrient-poor white pine swamp with several northern plant species growing in association with it, and a maritime oak forest exposed to salt spray with a dense understory shrub layer dominated by black huckleberry and bayberry (Myrica pensylvanica).
VII. THREATS: Residential development along the South Fork shoreline in this area poses a potential threat to water quality and elimination of shoreline habitat of regionally important fish, wildlife and plant species. The impressive and growing population of ospreys in the area attests to the present quality of their nesting and feeding habitat, which could, however, be reversed by large scale poorly-planned or unregulated development or shoreline construction. Human disturbances to nesting beaches of piping plovers and terns, in the form of destruction of nests or eggs through trampling, off-road vehicles, boat landings, vandalism or pets, is a common problem throughout the greater Peconic Region and can lead to seasonal or even permanent abandonment of these sites. Vegetation succession at these sites can also lead to these sites no longer being suitable for nesting. Ospreys are also affected by human disturbances during the nesting and fledgling periods.
VIII. CONSERVATION CONSIDERATIONS: Protection of water quality and significant aquatic habitats should be given the highest priority to ensure the continued high value of this area to wintering and migrating waterfowl, shellfish, spawning and juvenile fish, marine and estuarine turtles, nesting waterbirds and ospreys. Protective measures should include the full array of available mechanisms, including regulatory overview and enforcement of existing environmental laws and regulations, development and implementation of ecologically sound zoning and planning policies and practices, seeking opportunities to develop cooperative conservation and management agreements, conservation easements, land exchanges and acquisition. There are a number of opportunities and challenges here for various governmental agencies, conservation organizations, citizen groups and private landowners to work cooperatively in conserving and protecting the living resources of this area. Disturbances to nesting beach birds, wintering waterfowl and nesting ospreys should be minimized or eliminated by a variety of means, including protective fencing, area closures, posting, warden patrols and public education. Where predation by pets or feral animals, particularly on nesting beaches of terns and piping plovers, is determined to be a problem, predator removal practices should be implemented. Efforts should be made to identify and implement objectives and tasks outlined in the piping plover recovery plan. Conservation and management plans, including fire management, for certain rare plants, for example, sea-beach knotweed, and unique plant communities on Mashomack Preserve and Suffolk County parklands should be developed cooperatively to enhance, restore and protect such regionally important populations and natural communities on these lands.
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