KEY NORTH AMERICAN MIGRATION SITES FOR
Red Knots & Semipalmated Sandpipers

Delaware Bay

Country: USA

Region: Delaware, New Jersey

Site: Delaware Bay

Species/Sub-species: REKN-rufa, SESA

Total biogeographic population: 42,000 (rufa)1, 2,260,000 (SESA)

Count Method: Total estimate (rufa), maximum day count (SESA)

Count: 25,548 (rufa)2, 267,348 (SESA)3 ,4,5

% biogeographic pop. at site: 60.83 (rufa), 11.83 (SESA)

Season (primarily): Spring

Site recognition: WHSRN Ramsar IBA

Site recognition (other): National Wildlife Refuges, Wildlife Management Areas (Cape May National Wildlife Refuge, NJ, and Bombay Hook and Prime Hook National Wildlife Refuges, Delaware. New Jersey Wildlife Management Areas include: Mad Horse Creek, Dix, Egg Island, Fortescue, Nantuxent, Heislerville, Dennis Creek, and Higbee Beach. Delaware Wildlife Management Areas include: Woodland Beach, Little Creek, Ted Harvey, Prime Hook and Cape Henlopen.)

Site description: Using the Ramsar Classification System for Wetland Type, the site's habitat characteristics are coastal, including sand beaches, intertidal mud sand or salt flats, intertidal marshes, and coastal freshwater lagoons. Shorebirds are found along sandy beaches and at the mouths of creeks feeding on horseshoe crab eggs5. Land ownership is federal (U.S. Fish and Wildlife), state (New Jersey and Delaware Division of Fish and Wildlife), local governments and private landowners6. Existing knowledge about the site has been gathered through shorebird banding and geotagging; horseshoe crab tagging; a comprehensive management plan for tidal wetlands (including recommendations for shorebird habitat); and the Delaware General Assembly Bill 1991 to regulate harvesting of horseshoe crab. Work currently underway in 2016 includes the Celebrate Delaware Bay Network (outreach), restoring beaches, the Bayshore Steward Program, and land purchase. The Nature Conservancy launched a 3-year, US$15 million fundraising campaign to acquire 13,500 square miles along the Delaware River Basin and additional areas are protected by The Natural Lands Trust, New Jersey Natural Lands Trust, and the Cape May County Park Commission.

Known threats: Extraction of nonrenewable resources is a threat, and specifically energy production and mining (the threat from renewable energy from windfarms is moderate). In terms of renewable resources, the threat from over-exploitation, persecution and control of species through habitat effects (fishing and harvesting of aquatic resources) and largescale/industrial extraction (horseshoe crab harvest for bait and medical use) is very high. Horseshoe crabs have been severely overharvested by the conch and eel fisheries, which use them as bait. Site land use change due to natural system modification (dams and water management use and specifically canals), and transportation/service corridors (shipping lanes and ports) also poses a medium threat. The threat from pollution in the form of industrial and military effluents (oil spills) is high. In terms of damaging recreational use, the threat of human intrusions and disturbance from recreational activities and from work and other activities is high; and from invasives and other problematic species (i.e. domestic animals such as pets) is moderate. Lastly, the threat of physical alteration of the site from climate change in the form of severe weather (storms and floods) is high, from habitat shifting and alteration is moderate; and from invasive/problematic species and genes (pathogens/parasites such as avian flu) is high. Climate change may also be a threat in terms of the time of arrival of birds and horseshoe crabs.7,8

Notes: The site follows the WHSRN site boundaries.

Sources: 1A. Dey, pers. comm. in Andres, B.A., P.A. Smith, R.I.G. Morrison, C.L. Gratto-Trevor, S.C. Brown, and C.A. Friis. 2012. Population estimates of North American shorebirds. Wader Study Group Bulletin 119(3): 178-194. 2WHSRN site nomination form. 3Clark, K., L. Niles and J. Burger.1993. Abundance and distribution of shorebirds migrating on Delaware Bay, 1986- 1992. Condor 95: 694–705. (May-June 1986) 4International Shorebird Survey. 5Mizrahi, D.S. and M. Gutowski 2013. Conservation plan for the Semipalmated Sandpiper (Calidris pusilla). Unpublished draft. 6WHSRN Site Assessment Tool 2012 7Site Assesment Tool Analysis 2010 8Baker, A.J., P.M Gonzalez, T. Piersma, L.J. Niles, I.L.S. Nascimiento, P. W. Atkinson, N. A. Clark, C.D.T. Minton, M.K. Peck and G. Aarts. 2004. Rapid population decline in red knots: Fitness consequences of decreased refueling rates and late arrival in Delaware Bay. Proc Biol Sci. 271(1541): 875–882.