Woman holding binoculars Join today and get outside at one of our 60+ wildlife sanctuaries.
Woman holding binoculars Join today and get outside at one of our 60+ wildlife sanctuaries.
Northern Harrier flying
Northern Harrier © Kyle Wilmarth

Important Bird Area: Cape Cod National Seashore

Map of the Cape Cod National Seashore, incl. Wellfleet Bay Wildlife Sanctuary IBA site

Nominated By

Robert Cook


46,000 acres

Towns and Counties

Eastham, Provincetown, Truro, Wellfleet; Barnstable


state, National Park Service, municipal, private, Mass Audubon

Major Habitats

29% marine/tidal, 29% pitch pine /scrub oak forest, 8% coastal beach, 7% oak-conifer transitional forest, 7% maritime heathland /sandplain grassland, 6% early successional shrubland, 4% salt marsh, 4% urban/suburban, 2% emergent freshwater wetland, 2% lake/pond 1% northern hardwood forest

Land Use

nature & wildlife conservation/land trust, hunting/fishing, other recreation or tourism, fisheries/aquaculture, water supply, suburban/residential, research

Serious Threats

invasive or non-native plants, succession, disturbance to birds, recreational development/overuse, hydrologic changes

Minor Threats

introduced animals, pesticides, water pollution, soil erosion, residential 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 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

Cape Cod National Seashore (CCNS) and Wellfleet Bay Wildlife Sanctuary (WBWS) preserve approximately 46,000 acres of uplands, wetlands, tidal lands, and shallow marine waters located along approximately 50 miles of shoreline on Outer Cape Cod. CCNS and WBWS are characterized by a mosaic of natural and cultural resources, which are the result of dynamic natural processes and at least 9,000 years of human activity.

The natural terrain contains an exceptional array of coastal communities including pitch pine/oak forest, heathlands (nearly the entire eastern US distribution of heathlands is restricted to fragments on the Outer Cape and in coastal Maine), dunes, and coastal plain pond shores. There is also a wide diversity of aquatic and marine habitats, including kettle ponds, cedar swamps, vernal pools, drowned river valley salt marshes, back barrier slat marshes, barrier spits, and intertidal mudflats. These habitats support numerous state, federal, and globally rare, threatened, and endangered species of plants, invertebrates, and vertebrates, along with approximately 370 species of birds, of which approximately 80 are breeders. For many species of plants and animals, CCNS and WBWS provide some of the highest quality remaining coastal plain habitat in New England and the area offers prime opportunities for their regional preservation.

Current Conservation Status

Invasive/Non-native Plants: Survey work conducted in 2000-2001 determined that approximately 25% of the 830 plant species at CCNS were non-native. Acreage of alien-dominated habitats were calculated, invasiveness of species were determined, and management priorities were established. Some efforts at controlling garlic mustard were initiated in 2001. Feral and Pet Cats: While knowledge of the general literature on this subject suggests there may be problems, there are no CCNS-specific data on numbers of cats or their impacts. The Monitoring Avian Productivity and Survivorship program is comparing avian productivity at high- versus low-density residential sites, which may illuminate this.

Succession: While the return of woodlands represents a return to pre-European conditions, suppression of fire (both historically and now because of high-density housing), and development may result in the decline of heathland/grassland habitats to levels below pre-European conditions, and a loss of associated animal species. CCNS monitors vegetation at the park level, through aerial photo-based vegetation maps, as well as within habitats through quadrat methods. Heathland study sites established about 1989 were resampled in 2001. Heathland/grassland birds were surveyed in 1995 and in 2000, documenting a 50% decline in the Vesper Sparrow. Grassland habitat at Fort Hill is being managed through fire, mowing, and hand cutting, but no management plans for heathlands have been developed yet.

Overfishing: Commercial shellfishing occurs throughout CCNS, but is not thought to be a problem. Until recently, commercial harvest of horseshoe crabs occurred.

Predators: Principal predators of concern to avian conservation are Eastern Coyotes, Red Foxes, Great Horned Owls, and American Crows. While native predators, at natural densities, are not a great concern, human-enhanced densities of "subsidized" predators would be a concern, particularly when Threatened and Endangered species are involved. At present, coyotes and foxes are not a significant problem to terns and plovers (because of protection by predator enclosures), but crows are a significant Piping Plover predator, and Great Horned Owls are sometimes a significant tern predator at New Island. The National Park Service is testing the use of wolf and/or coyote urine as a deterrence to fox predation.

Water Pollution: There is concern over nutrient enrichment of kettle ponds and estuarine habitats from pollution by septic and fertilizers. There is growing evidence of increased nutrient levels in these systems (e.g., algal blooms in Salt Pond, Eastham, in 2001). CCNS is conducting intensive long-term water-quality monitoring of Kettle Ponds, and less frequent monitoring of estuarine waters. With the US Geologic Service (USGS), CCNS is studying transport of nutrients in groundwater from septic systems to ponds/estuary.

Air Pollution: Air at CCNS often has high levels of ozone and mercury (in precipitation) and precipitation pH is 4.4 to 4.6. Air quality is monitored at CCNS in cooperation with the Department of Conservation and Recreation. Precipitation chemistry (e.g., acid rain) is monitored at CCNS in cooperation with the National Atmospheric Deposition Program. Mercury in kettle ponds and pond-inhabiting fish has been detected.

Excessive Soil Erosion/Degradation: There was extensive historic soil loss/degradation during the agrarian period, particularly in the Provincelands. Visitors continue to trample many areas of the park, inhibiting natural revegetation and maintaining unnatural erosion.
Residential/Commercial Development: Growing numbers of year-round residents use the park as a backyard. Therefore, there are concerns over loss and degradation of adjacent habitats, increased groundwater withdrawal from common aquifers, and an increased level of predation by pets.
Disturbance to Birds/Habitats: There are more people, using more areas of CCNS, for a much greater portion of the year than ever before. In addition to traditional beach uses and beach buggies, there are now mountain bike trails being created in wooded areas by cyclists, kayakers are now numerous in many hitherto inaccessible salt marsh creeks, and significant numbers of boaters landing at all the remote, distal ends of peninsulas. CCNS and USGS are working to develop protocols for monitoring visitor impacts to wildlife and vegetation.

Ornithological Significance

Cape Cod National Seashore and Wellfleet Bay Wildlife Sanctuary are important for Massachusetts' birds because of the amount and type of habitats they provides and the fact that they are managed by the National Park Service and Mass Audubon, respectively. Both entities make considerable effort to protect resident and migrant birds from disturbance and habitat destruction.

CCNS is important because it supports significant breeding populations of certain Threatened and Endangered species (e.g., terns, Piping Plover, Vesper Sparrow) and also because it provides important migratory and wintering habitat for large numbers of shorebirds, waterfowl, wading birds, and seabirds. It also supports significant breeding populations of many high conservation priority species. For some of these species, fairly specific and discrete sections of the park can be identified as being highly important, whereas species with large home ranges (e.g., Northern Harrier) and those that do not aggregate (e.g., most terrestrial breeders) utilize broad areas of appropriate habitat Detailed overviews of CCNS avifauna are provided by Bailey (1968), Cape Cod Bird Club (1990), and Veit and Petersen (1993).

Other Flora or Fauna of Significance

Federally Listed: Loggerhead, Green Turtle, Hawksbill, Atlantic Ridley, Leatherback, Harbor Seal, Harp Seal, Gray Seal, Hooded Seal, Sperm Whale, Atlantic White-sided Dolphin, Orca, Pilot Whale, Harbor Porpoise, Finback Whale, Sei Whale, Minke Whale, Blue Whale, Humpback Whale, Right Whale

State Listed: Non-avian vertebrates—Four-toed Salamander, Eastern Spadefoot, Spotted Turtle, Northern Diamondback Terrapin, Eastern Box Turtle, Gray Seal 

Invertebrates—Walker's Limpet, New England Bluet, Pine Barrens Bluet, Coastal Heathland Cutworm, Blueberry Sallow, Gerard's Underwing Moth, Chain Dot Geometer, Northern Hairstreak, Coastal Barrens Buckmoth, Decodon Borer Moth

Data Sources

Bailey, W. 1968. Birds of the Cape Cod National Seashore and adjacent areas. Eastern National Park and Monument Association. 120 pp.

Blodget, B. 2000. Massachusetts Tern Inventory 2000. Massachusetts Division of Fisheries and Wildlife, Westborough MA.

Brown, J. 1994. Species composition, migration chronology, and habitat use of waterbirds at Cape Cod National Seashore. M.Sc. Thesis, Univ. of Rhode Island. 152 pp.

Cape Cod Bird Club. 1990. Birding Cape Cod. Massachusetts Audubon Society, Wellfleet Bay Wildlife Sanctuary, Wellfleet, MA. 124 pp.

DeSante, D.F., N. Michel, and D.R. O'Grady. 2001. The 2000 Annual Report of the Monitoring Avian Productivity and Survivorship (MAPS) program in Cape Cod National Seashore. Institute for Bird Populations, Point Reyes Station, CA. 40 pp.

Erwin, R.M., C. Conway, and S. Hadden (in press). Assessing the status of Marsh Birds at Cape Cod National Seashore: Methods for Monitoring. Northeast Naturalist.

Faherty, Mark. University of Massachusetts, Amherst. personal communication. 1/14/2002. Species observed on point counts in Cape Cod National Seashore, summer 2001.

Hadden, S. 2001. Waterbird inventory and monitoring: Report on protocol implementation and development at Cape Cod National Seashore. Cape Cod National Seashore, Wellfleet, MA. 66 pp.

M. Hake and E. Schneider. 2001. Monitoring and managing of piping plovers and colonial waterbirds at Cape Cod National Seashore. Cape Cod National Seashore. CACO Natural Resource Report 01-02. 47 pp

Kearny, S.B. and R.P Cook. 2001. Status of grassland and heathland birds at Cape Cod National Seashore. USDI, NPS, Boston Support Office, Technical Report NPS/BSO-RNR/NRTR/2002-3

Lowe, M. personal communication. Pilgrim Height Hawk Watch, spring migration summary 1998-2001.

Massachusetts Audubon Society, 1997. Wellfleet Bay Wildlife Sanctuary. A checklist of the birds.

Mostello, C.S. and S.M Melvin. 2001. Summary of 2000 Massachusetts Piping Plover Census Data. Massachusetts Division of Fisheries and Wildlife, Westborough MA.

National Park Service. 1998. Forging a collaborative future. Final Environmental Impact Statement for the General Management Plan. Volume 1. Environmental Impact Statement. USDI, National Park Service, Cape Cod National Seashore. 374 pp.

Pyle, P., D.F. DeSante, and D.R. O'Grady. 2000. The 1999 Annual Report of the Monitoring Avian Productivity and Survivorship (MAPS) program in Cape Cod National Seashore. Institute for Bird Populations, Point Reyes Station, CA. 32 pp.

Trull, P., S. Hecker, M.J. Watson, and I.C.T. Nisbet. 1999. Staging of Roseate Terns Sterna dougallii in the post-breeding period around Cape Cod Massachusetts, USA. Atlantic Seabirds 1(4):145-158.

Tuxbury, K. 2001. Abundance, distribution, and disturbance of shorebirds in Wellfleet Harbor. Massachusetts Audubon Society, Wellfleet Bay Wildlife Sanctuary.

Veit, R. and W.R Petersen. 1993. Birds of Massachusetts. Massachusetts Audubon Society. 514 pp.