Parker River National Wildlife Refuge

Ecology and Management

The impoundments at Parker River National Wildlife Refuge provide critical habitat to thousands of shorebirds, wading birds and waterfowl. The refuge and its impoundments are located within the Great Marsh, the largest contiguous salt marsh in New England, an Important Bird Area of global significance, and a WHSRN site of regional importance. During migration, the area as a whole supports over 67,000 shorebirds representing 30 different species. When managed, Bill Forward and Stage Island Impoundments provide foraging and roosting habitat to high concentrations of shorebirds during migration. North Pool is primarily managed for breeding marsh and wading birds. Parker River National Wildlife Refuge had used the Integrated Waterbird Management and Monitoring (IWMM) protocol to assess bird use of their impoundments. Even though they no longer participate in IWMM, many years of their data are still in the database, and summarized in the Annual Habitat Work Plans. According to data from eBird, 213 species of birds have been observed at Bill Forward Pool, 235 species at Stage Island Pool and 165 species at North pool. High counts from the Hellcat Dike (which separates North pool and the Bill Forward Pool) include 600 Black-bellied Plovers, 1,500 Semipalmated Plovers, 215 Greater Yellowlegs, and 2,285 Semipalmated Sandpipers. Rare and endangered species also nest in the impoundments during the summer months. Breeding data from surveys done from 2005-2011 reveal that breeding of Least Bittern and American Bittern were in the North Pool. Historically, Pied-billed Grebes have also likely bred in the North Pool. All three species are on the Massachusetts endangered species list.

Like many impoundments constructed in the 1940s and 1950s, the impoundments at Parker River NWR were constructed to benefit Black Ducks. However the focus of the impoundments has shifted to a multiple species approach. Current management practices are designed to provide habitat for wading birds, waterfowl, breeding birds, and migratory shorebirds. North Pool is kept primarily as fresh water habitat and Bill Forward and Stage Island as brackish water (10-15% salinity). Water levels are typically held high in all three impoundments during the summer breeding season, but during spring and fall migration the water level is drawn down in Stage Island and Bill Forward to provide migratory stopover habitat for shorebirds. Invasive species (Phragmites) management is also considered a high priority in these impoundments to help create habitat more suitable for shorebirds and waterfowl. Management is designed to increase rushes, sedges, and mudflats – ideal feeding areas for waterfowl and shorebirds. Invasive plants are primarily controlled by manipulating water levels and by seasonal mowing.

Vulnerability

All three impoundments at Parker River NWR are at, close to, or below mean high water. However the impoundments are sheltered from storm-driven flooding. On the ocean side, large vegetated dunes prevent storm surge from reaching the impoundments. On the bay side, vast stretches of high and low marsh reduce the likelihood of flooding. According to refuge staff, none of the impoundments have ever been impacted by storm-driven erosion or overtopping. With the predicted change in Plum Island Sound, higher vulnerability is expected in the future, with enlarged open water and narrower salt marsh.

Human Value

Approximately 240-250 thousand people visit the refuge each year. According to a visitor study conducted in 2010/2011, the top activity reported by those surveyed were bird watching (67%) and wildlife observation (61%). Although it’s impossible to know where exactly visitors spent their time watching birds and wildlife, it is more than likely that a majority of these folks went to one or more of the refuge’s impoundments where birds and wildlife are most easily visible.

Acknowledgements

We are grateful to Nancy Pau and Bill Peterson (Park River NWR) for providing helpful information used on this page.

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