Nominated By: Kathleen Anderson

Size: 20,362 acres

Towns and Counties:
Duxbury, Kingston, Marshfield, Plymouth; Plymouth

Ownership:
municipal, private, nongovernmental organization

Major Habitats:
80% marine/tidal8% salt marsh7% coastal beach5% other (oak-conifer transitional forest, river/stream, urban/suburban, early successional shrubland, cultural grassland)

Land Use:
nature & wildlife, conservation/ land trust, recreation, hunting & fishing, fisheries/aquaculture, undeveloped, suburban/residential, research

Serious Threats:
predators, habitat conversion, disturbance to birds or habitat, recreational development/overuse

Minor Threats:
invasive or non-native plants, introduced animals/feral pets, water/ air pollution, residential/commercial development

IBA Criteria:

• Category 1: Sites important for long-term research and/or monitoring projects that contribute substantially to ornithology, bird conservation, and/or education.



• Category 2: Sites containing assemblages of species characteristic of a representative, rare, threatened, or unique habitat within the state or region.



• Category 3: Sites where birds concentrate in significant numbers in the breeding season, in winter, or during migration.


• 3a. Shorebirds: The site regularly supports 1,000 or more shorebirds at one time at a coastal site, during some part of the year, or a significant concentration of shorebirds at one time at a nontidal site. The designation "shorebirds" includes birds such as plovers, sandpipers, snipe, woodcocks, and phalaropes.
  


• 3b. Waterfowl: The site regularly supports 500 or more waterfowl at any one time. The designation "waterfowl" includes birds such as loons, grebes, cormorants, geese, ducks, coots, and moorhens.
  


• 3c. Wading Birds: The site regularly supports 25 or more breeding pairs of wading birds or 100 or more foraging individuals (at one time) during migration. The designation "wading birds" includes bitterns, herons, egrets, and ibises.
  


• 3e. Seabirds: The site regularly supports 300 or more pelagic seabirds and/or terns or 3,000 or more gulls at one time. A pelagic site is the actual location being used by seabirds (e.g., Stellwagen Bank) and not the location from which an observer counts seabirds (e.g., Provincetown). Smaller concentrations of less common gulls such as Laughing or Bonaparte’s gullswill be considered. Human-made food sources for gulls such as landfills and sewage outflows will not be considered. The designation "seabirds" includes shearwaters, storm-petrels, fulmars, gannets, jaegers, and alcids.
  





• Category 4: Shorebirds: The site regularly supports 1,000 or more shorebirds at one time at a coastal site, during some part of the year, or a significant concentration of shorebirds at one time at a nontidal site. The designation "shorebirds" includes birds such as plovers, sandpipers, snipe, woodcocks, and phalaropes.



• Category 5: Waterfowl: The site regularly supports 500 or more waterfowl at any one time. The designation "waterfowl" includes birds such as loons, grebes, cormorants, geese, ducks, coots, and moorhens.

Site Description:
The Plymouth Bay Complex, within the boundaries of Plymouth, Kingston, and Duxbury, is one of the state's largest natural embayments with approximately 10,233 acres of bay, 4,600 acres of mudflats at low tide, 800 acres of salt marsh, and 526 acres of beach. The total length of the shoreline is 55 miles, which includes 16 miles of barrier beach.

Current Conservation Status:
Overuse of Plymouth and Duxbury beaches by four-wheel-drive vehicles is a major disturbance and threat to shorebirds, terns, and the federally listed Piping Plover. Erosion-control practices on beaches, such as the use of snow fence, discarded Christmas trees, and the planting of beach grass and other vegetation, pose threats to Least Tern and Piping Plover habitats. Mass Audubon and MassWildlife are working with the town governments to reduce these impacts.

Federally Listed Species:

Species	Breeding	Winter	Migration
Roseate Tern	30 pairs 1995	*	*
Piping Plover	24 pairs 1999	*	*

* None known

State Listed Species:

Species	Breeding	Winter	Migration
Common Tern	4,967 pairs 1997	*	*
Arctic Tern	4 pairs 1998	*	*
Least Tern	252 pairs 1996	*	*

* None known

Other Flora or Fauna of Significance:
These bays, with their extensive salt marshes, tidelands, and Eelgrass beds, are major nurseries of marine fish, shellfish, horseshoe crabs, and other marine invertebrates. Several rivers entering the bays of this site, including Eel River, Town Brook, Jones River, Bluefish River, and the Green Harbor Creek, support spawning populations of anadramous and/or catadromous fish species, such as Alewives, Blueback Herring, Rainbow Smelt, and American Eel.

Data Sources:
Clough, T. Brant Data. Manomet Center for Conservation Sciences files (fide Trevor Lloyd-Evans).

Harrington, B.A. Shorebird data from Manomet Center for Conservation Sciences.

Hecker, S. and B. Blodget. Piping Plover and tern data. MassWildlife and Massachusetts Audubon Society (personal communication).

Heusmann, H.W. 2001. Black Duck and Common Eider numbers (personal communication).

Iwanowicz, H.R., R.D. Anderson, and B.A. Ketscke. 1974. A study of the marine resources of Plymouth, Kingston, and Duxbury Bay. Monograph Series 17, Division of Fisheries, Dept. of Natural Resources, Commonwealth of Massachusetts.

Massachusetts Coastal Zone Management Plan - Chapter 5 of Vol. II. Massachusetts Coastal Regions and An Atlas of Resources.

Morrison, R. I. G. et. al. 2001. Estimates of Shorebird Numbers. Occasional Paper Number 104. Canadian Wildlife Service.

Veit, R.R and W.R. Petersen. 1993. Birds of Massachusetts. Massachusetts Audubon Society, Lincoln.

Records fromBird Observer, 1974-2000.

Map:
Download Plymouth and Duxbury Bays Map*    (file size - 703 kb)