There are 30 species of migratory shorebirds, plovers, sandpipers, avocets, and oystercatchers, that regularly use marine and freshwater habitats and adjacent uplands in the New York Bight watershed for breeding, wintering, northward (spring) migration, or southward (autumn) migration . Most of these species of shorebirds breed in interior regions of North America, especially in the Arctic and subarctic, and spend two-thirds to three-quarters of the year on migration routes and wintering grounds. Seven shorebird species nest within the New York Bight watershed, including beach-nesting shorebirds (discussed under the colonial waterbird chapter) and grassland-nesting species (discussed under the Neotropical migrant chapter). Shorebirds show a strong affinity for wetlands, and typically swarm the beaches, marshes, and tidal flats during migration. Large numbers of migratory shorebirds travel great distances between breeding and wintering grounds and concentrate in small stopover areas with seasonally-abundant food resources to accumulate energy reserves for continuing their long-distance flights. Because large numbers of shorebirds are concentrated in just a few areas during migration, loss or degradation of key sites could devastate these populations. Analyses of the International Shorebird Survey (ISS) data⁽¹⁾ have indicated recent declines in several species of shorebirds, including black-bellied plover (Pluvialis squatarola), whimbrel (Numenius phaeopus), red knot (Calidris canutus), sanderling (Calidris alba), semipalmated sandpiper (Calidris pusilla), least sandpiper (Calidris minutilla), and short-billed dowitcher (Limnodromus griseus); counts at Delaware Bay have also documented regional declines in sanderling and semipalmated sandpiper.

¹The International Shorebird Survey is a volunteer shorebird survey at over 600 sites in the United States coordinated by the Manomet Center for Conservation Sciences. Cooperators census shorebirds three times monthly during key migration periods at a site selected by the cooperator. There are 28 survey sites within the New York Bight study area, mostly concentrated in the backbarrier lagoons along the New Jersey and Atlantic coasts (see Figure 8).

Shorebirds migrate through the New York Bight almost all year round, with northward migration beginning in late winter and lasting through June, and southward migration beginning in late June with peaks in late July and lasting into the fall. Shorebirds rely on a mosaic of shallow coastal or freshwater wetlands and adjacent upland areas. Foraging habitats include beaches, mudflats, sandflats, salt marshes, impoundments, flooded agricultural fields, and grasslands. In coastal areas, preferred food items include macroinvertebrates such as polychaete worms, crustaceans, mollusks, or insects. Roosting habitats, usually used at night or during high tide periods when primary feeding areas are not accessible, include salt marshes, sandflats and beaches above the tide line, and sparsely vegetated islands free of predators. Although migrating shorebirds occur throughout the shallow bays and estuaries of the New York Bight, especially during the autumn migration, there are relatively few sites that consistently support large numbers of shorebirds. Analyses of ISS data, Christmas bird counts, and migration season accounts from American Birds for the Western Hemisphere Shorebird Reserve Network (WHSRN) identified seven sites with counts of 5,000 or more shorebirds partially or wholly within the New York Bight watershed during spring, autumn, or winter. These sites, from south to north, include Delaware Bay (spring migration), Cape May (wintering), Great Egg Harbor (autumn and spring migrations), Brigantine Beach (autumn migration), Brigantine (E.B. Forsythe) National Wildlife Refuge/Oceanville (autumn migration and wintering), Jamaica Bay (autumn and spring migrations), and Hackensack Meadowlands (autumn migration). Delaware Bay has been designated as a hemispherically important site under WHSRN. There are also important shorebird concentration areas along the south shore of Long Island and other bays in New Jersey that appear to be under-represented in the ISS database and may have similar levels of shorebird use. Since these surveys are not systematic, it is very likely that the shorebird use in the New York Bight is underestimated and that additional sites of regional or national importance to shorebirds are yet to be identified.

The shoreline of Delaware Bay, including the Cape May shoreline, is a critical spring migration stopover for shorebirds, with peak single-day counts of 200,000 to 400,000 birds and estimated totals of 800,000 to 1.5 million shorebirds passing through Delaware Bay each spring. Delaware Bay is the largest spring shorebird staging area on the east coast of the United States, and one of the top ten sites in the Western Hemisphere. Six species make up 95% of the birds staging in Delaware Bay in the spring: semipalmated sandpiper, red knot, ruddy turnstone (Arenaria interpres), and sanderling, with lesser numbers of dunlin (Calidris alpina) and short-billed dowitcher. The peak stopover is synchronized with the availability of horseshoe crab eggs along the Delaware Bay shoreline; the bay is reported to contain the largest concentration of horseshoe crab eggs in the eastern United States. Shorebirds are dependent on the variety of estuarine habitats on both the Delaware Bay and Atlantic coast sides of the Cape May Peninsula (for additional detail, see narrative for Cape May Peninsula).

The greatest threats to migrating shorebirds in the New York Bight are loss and degradation of coastal habitats and human disturbance. Protection efforts for shorebirds should focus on preserving and protecting key foraging and roosting habitats, reducing disturbance, and enhancing and restoring wetland and adjacent upland habitats. Remaining coastal areas with high densities of shorebirds during migration periods need to be protected from further development or degradation through acquisition, easements, or other means. Disturbance of shorebirds at feeding and roosting sites should be minimized through posting, fencing, public education, and other means. At publicly owned sites, access to key feeding and roosting areas should be limited during migration periods. Migrating shorebirds are concentrated and particularly vulnerable at roosting sites during high tide. Improving and maintaining water quality in the coastal bays and estuaries of the New York Bight watershed should be a priority in order to maintain and improve the invertebrate food base upon which shorebirds depend. Key migration stopover sites are extremely vulnerable to oil and chemical spills and should have contingency plans and equipment in place in case a spill occurs. Coastal wetland habitats and adjacent upland habitats should be restored, enhanced, and managed for a diversity of wildlife, including shorebirds and waterfowl. Restoration and enhancement of high marsh habitat, especially salt pannes, would benefit shorebirds. Open marsh water management (OMWM) is a technique being employed to enhance salt marsh habitat through creation of ponds and channels; OMWM ponds should be constructed with shallow sloping shorelines and islands to benefit shorebirds. Management of impoundments should be planned and implemented to maximize both invertebrate availability for shorebirds and plant seed production for waterfowl. Upland areas should be managed to create short sparse vegetation for nesting and foraging shorebirds.

References:

Burger, J. 1984. Abiotic factors affecting migrant shorebirds. In J. Burger and B.L. Olla (eds.) Behavior of marine animals, vol. 6, shorebirds: migration and foraging behavior, pp. 1-72. Plenum Press, New York, NY.

Clark, K., L. Niles, and J. Burger. 1993. Abundance and distribution of shorebirds migrating on Delaware Bay, 1986-1992. The Condor 95:694-705.

Dunne, P., R. Kane, and P. Kerlinger. 1989. New Jersey at the crossroads of migration. New Jersey Audubon Society, Franklin Lakes, NJ. 74 p.

Harrington, B.A, J.P. Myers, and J.S. Grear. 1989. Coastal refueling sites for global bird migrants. Coastal Zone '89, Proceedings of the Symposium of Coastal and Ocean Management, pp. 4293-4307. American Society of Civil Engineers, New York, NY.

Harrington, B.A. and J.L. Lyons. 1990. On the importance of wildlife areas in the United States to shorebirds migrating east of the 105th longitude line. Draft report prepared for the National Fish and Wildlife Foundation, Washington, D.C. Manomet Bird Observatory, Manomet, MA.

Harrington, B. and E. Perry. 1995. Important shorebird staging sites meeting Western Hemisphere Shorebird Reserve Network criteria in the United States. Wildlife Habitat Canada and Western Hemisphere Shorebird Reserve Network, Manomet Observatory, Manomet, MA. Working draft.

Hayman, P., J. Marchant, and T. Prater. 1986. Shorebirds: an identification guide to the waders of the world. Houghton Mifflin, Boston, MA.

Helmers, D.L. 1992. Shorebird management manual. Western Hemisphere Shorebird Reserve Network. Manomet, MA. 58 p.

Howe, M.A., R.B. Clapp, and J.S. Weske. 1978. Marine and coastal birds. Marine Ecosystems Analysis Program New York Bight Atlas Monograph 31. New York Sea Grant Institute, Albany, NY.

Howe, M.A., P.H. Geissler, and B.A. Harrington. 1989. Population trends of North American shorebirds based on the International Shorebird Survey. Biological Conservation 49:185-199.

Niles, L.J., K. Clark, and S. Paul. 1994. Comprehensive management plan for shorebirds on Delaware Bay. New Jersey State Endangered and Nongame Species Program, Division of Fish, Game and Wildlife, Trenton, NJ.

Pfister, C. and B.A. Harrington. 1992. The impact of human disturbance on shorebirds at a migration staging area. Biological Conservation 60:115-126.

 print