Documenting Bird Life in Delaware Bay Salt Marshes

by Harrison Hepding, CWF Biological Technician

The remote coastal salt marshes of the Delaware Bayshore harbor a unique and seldom observed ecosystem, boasting a rich natural history and diverse wildlife. To help prevent the loss of these valuable habitats and their inhabitants, CWF is participating in a partner-driven, multi-year project led by Ducks Unlimited and the U.S. Fish & Wildlife Service to enhance habitat quality and restore natural hydrology to salt marshes in Delaware and New Jersey. CWF is actively involved in the second season of biological monitoring at select Bayshore salt marshes targeted for restoration efforts designed to revegetate mudflats existing on old salt hay farms (read more about salt hay farming impacts here). At this stage of the project, our role is to gather important pre-restoration data to evaluate the anticipated impact and effectiveness of restoration techniques.

One element of data being collected is the composition of bird communities currently found within our restoration sites. This information is collected through something called a “point count,” which is a survey used by bird researchers to take a snapshot of species composition and abundance in a targeted area. Point counts are stationary surveys, where the observer will document all birds that they can detect, either visually or by sound. Throughout the survey window of May 1 through July 15 we conducted point counts at our three survey sites twice, collecting data at multiple points within each site’s designated restoration area. This was done using a protocol created by the Saltmarsh Habitat and Avian Research Program, or SHARP for short. Surveys were thirteen minutes long and included five minutes of passive surveying, followed by eight minutes of broadcasting calls from various species that could be found in our coastal salt marshes. Certain species are secretive and hard to see, but they can be quite receptive to hearing their own species’ calls and will vocalize in response, hence the call broadcast portion of the survey. 

We documented an interesting array of species throughout our sites, with some being very abundant and characteristic of the marshes we surveyed. The seaside sparrow is one of these species, with their buzzy song being a comforting beacon of salt marsh habitat. Across all our point counts we recorded 62 incidences of seaside sparrows. This species is one that would benefit greatly from the restoration of these marshes, as their nesting strategy is to create nests in saltmarsh cordgrass (Spartina alterniflora), which is the dominant species of grass that you see when you look at expanses of coastal saltmarsh. Because of this strategy, seaside sparrows are vulnerable to nest flooding with high tides, particularly in the context of increasing sea level rise and marsh erosion. Restoration efforts will also target the saltmarsh sparrow, a cherished species related to the seaside sparrow that is also found in our Atlantic Coast salt marshes. The saltmarsh sparrow has more stringent habitat requirements to nest and is proposed for federal listing as an endangered species. Perhaps unsurprisingly (given the current status of our restoration sites) we did not detect any saltmarsh sparrows throughout our surveys, but they could be detected in future monitoring surveys pending the successful restoration of these marshes! Additionally and interestingly, we detected a singing Nelson’s sparrow on May 29th at the old Garrison Salt Hay Farm; not a breeding bird here in New Jersey, but a scarce migrant species that utilizes New Jersey’s coastal salt marshes during their migration and wintering periods.

In addition to sparrows, we detected other bird species utilizing the salt marsh including a least bittern, a small, secretive marsh bird related to herons and egrets, at Dix Wildlife Management Area! Red-wing blackbirds were a dependable regular in the marshes as they sang, foraged, and defended their territories throughout almost every point we surveyed; they took the cake for our most detected species by over 100 detections. Clapper rails vocalizing with excitement was a regular occurrence, and they are one of those species that you will seldom see but surely hear! The clattering song of marsh wrens was apparent at almost any survey point. These small songbirds inhabit wetland areas across the country and can get pretty boisterous when you or another marsh wren gets near them. 

Our surveys offered an up-close view of the marshes that people seldom get to see, seeing them from within. This exposed us to quite unique habitats, seeing where high marsh remains. A hallmark sign of high elevation saltmarsh habitat is the presence of a plant species called saltmarsh hay (Spartina patens), a spindly grass that was the product of salt hay production in recent centuries. One of our survey points at the old Garrison Salt Hay Farm was situated in a beautiful patch of Spartina patens (saltmarsh hay). However, its decline was apparent as we saw Spartina alterniflora (saltmarsh cordgrass) colonizing the area, a sign of lower elevation from a subsiding marsh. A primary goal of the restoration project is to combat this subsidence and revive high elevation saltmarsh in areas where it is disappearing or has been degraded. Restoring high elevation marsh will benefit saltmarsh sparrows as well as black rails, two high marsh-dependent species that are facing population declines. Black rails have been detected near the previously mentioned Spartina patens patch, and restoration of this site could provide more ample nesting habitat for the species to ensure their population persists.

CWF Technician Harrison Hepding conducting a point count survey in a patch of high marsh Spartina patens (left) vs low marsh Spartina alterniflora (right).
Photos courtesy of Emmy Casper, CWF Wildlife Biologist.

As we conclude avian surveys at our restoration sites we look forward to our next phase of pre-restoration surveys. These include documenting marsh vegetation, collecting water level data, and surveying what aquatic animals are currently utilizing the salt marshes. Each aspect of this research provides insights into the current state of the ecosystem and will guide restoration efforts. Stay tuned as we continue to delve deeper into our work here on the Delaware Bay. We look forward to sharing more of the work we are doing as we aim to enhance and preserve these invaluable coastal habitats!