Dead Neck Sampsons Island Dredging/Renourishment Project—Restoring and Protecting Shorebird Habitat
Mass Audubon is seeking regulatory approval to restore coastal bird habitat on Dead Neck Sampsons Island.
What is the project?
Mass Audubon and Three Bays Preservation are seeking permits to restore coastal bird habitat on Dead Neck Sampsons Island by renourishing important nesting areas on the island. Dead Neck has been the site of many renourishment projects over the past 30 years. Sand that has been deposited on Dead Neck has eroded over the years and been carried westward to accrete at the western end of Sampsons Island. Renourishment will restore eroded nesting habitat for vulnerable shorebirds and strengthen the island against breaching. The dredging will restore the channel between the island and Cotuit which has filled in and has required dredging several times previously since the 1930s.
Why is Mass Audubon a proponent?
Mass Audubon works to protect the nature of Massachusetts. Mass Audubon’s Coastal Waterbird Program protects vulnerable populations of shorebirds on approximately 160 beaches in the state (more than 70 mi of coastline) through partnerships with private landowners and with local and state agencies. We protect about 40% of the piping plovers nesting in the state and about 50% of the least terns—both of these species are listed under the Massachusetts Endangered Species Act. Restoring habitat on the island will advance our objectives in bird conservation.
Who owns Dead Neck Sampsons Island?
Sampsons Island is owned by Mass Audubon having been given to us in the 1940s to be protected as a “as a tern sanctuary.” Dead Neck is owned by Three Bays Preservation and is managed under a conservation restriction for “bird protection… and conservation purposes.” Only about 10 of the 160 beaches that Mass Audubon protects are owned by Mass Audubon and therefore we have a relatively rare opportunity and strong obligation to protect nature on our own properties to exemplary standards.
How will the project serve to protect birds?
The dredging and renourishment project proposed by our two organizations will restore and protect habitat for coastal birds. Nourishment of Dead Neck will 1) restore acres of open sand habitat for nesting birds, 2) provide a sand source to widen the Nantucket Sound beach over approximately 5-10 years, and 3) protect the island from breaching. Protecting the island from breaching is critical to maintaining Dead Neck Sampsons Island as an island relatively isolated from mainland ground predators. Breaching is predicted to result in disintegration of the island, and cause the remainder of Dead Neck to join with Oyster Harbors; the remainder of Sampsons Island would attach to Cotuit. The project proposes to increase nesting and productivity through habitat restoration as described, and also through vegetation, predator and disturbance management.
What information is used to predict the outcomes of the project?
Coastal geologists are working on the project to direct the design. In addition, a similar project took place on the island in 2000 which produced desired outcomes. When a similar volume of material was placed on Dead Neck in 2000, we documented a dramatic increase in nesting terns and over time, increased abundance of nesting plovers as the south coast of the island widened. As that material drifted toward Sampsons Island and accreted, the number of pairs of all species declined again, and productivity also declined as the smaller nesting areas became more vulnerable to predators and storm overwash.
Have alternative designs been considered?
Alternative sources of sand for renourishment have been considered including a mainland source, other maintenance dredging in the area, and off-shore mining. All of these are less environmentally sound and more expensive than the proposed project. Sediments used to renourish Dead Neck must be compatible with existing sediment to provide new, safe nesting habitat. For example, incompatible sediment coming from an upland site might cause water to puddle which would create a hazardous nesting site for birds. No other channels in the region are available for dredging having been used in previous projects to strengthen the island. Off-shore mining from natural shoals is known to reduce habitat for sea ducks and other animals.
Finally, the coastline of Barnstable has been altered significantly through groins and shoreline armoring. These alterations have reduced the movement of sand from land to the coastline and caused some areas of the coast to be starved of sand leading to significant erosion such as at Dead Neck. Because of the movement of sand along the coast, Sampsons Island has accreted greatly over the past several decades. The project design replaces the sand from Sampson’s Island “upstream” to Dead Neck which provided the source of sand through previous renourishment projects. Adding additional “external” sand to the project through off-shore mining or from mainland sources would increase the need to dredge Cotuit channel to keep it from closing. The project is considered to take advantage of a closed sand transport system with sand being back-passed from Sampsons Island to its original source.
What are possible adverse effects of the project and how will they be mitigated?
In designing the project and through the permitting process we have considered possible adverse effects to storm damage protection, marine fisheries, shellfish, and coastal birds. We continue to solicit comments from the public and experts to avoid and minimize possible adverse effects. We anticipate that perhaps up to three nesting territories of plovers will be displaced through the removal of sand, however, based on prior projects we expect to gain 15 or more new nesting territories through habitat restoration and enhancement.
What’s at stake?
Dead Neck Sampsons Island has provided habitat to rare coastal birds for decades. It is the most important site for plovers on the southern Massachusetts coast west of Monomoy. In addition, large numbers of least and common terns have nested on the island historically. The endangered roseate tern has nested on the island and uses foraging habitats near the island to prepare for migration. Mass Audubon and Three Bays Preservation are dedicated to restoring habitat on the island to continue protection to these vulnerable coastal bird species.