Saltmarsh Sparrow (Ammospiza caudacuta) is an endemic species to the Atlantic Coast of the United States and is widely considered one of the most rapidly declining avian species in the Western Hemisphere. Population estimates over time suggest the species declined by about 87% over 15 years at an alarming rate of 9% per year (Hartley and Weldon 2020). The greatest threat to their existence on the broader scale is sea level rise as it relates to the imminent threat of anthropogenic climate change. Saltmarsh Sparrows rely on high marsh habitat dominated by salt hay (Spartina patens), saltmarsh cordgrass (Spartina alterniflora), and a variety of other specialist coastal plants for breeding, migration, and overwintering (Hartley and Weldon 2020). This type of habitat typically floods once or twice a month during extreme high tides which this species has naturally adapted its breeding cycle to work around. However, a foot or more of sea-level rise in some areas has pushed the birds to their limits resulting in increasingly low nestling survivorship (Hartley and Weldon 2020). However, in the New Jersey Meadowlands, there are other stressors that threaten the persistence of Saltmarsh Sparrow habitat.
Historically, Saltmarsh Sparrows held a small but steady breeding population within the New Jersey Meadowlands District. Records of their presence date back to at least 1997 when pre-restoration surveys were conducted in Harrier Meadow. New Jersey Sports and Exposition Authority Meadowlands Research and Restoration Institute (MRRI) biologists went on to find breeding pairs at as many as four different sites across the district as recently as 2017. Biologists working on the 2021 Meadowlands Breeding Bird Atlas as well as 2022 avian surveys specifically targeting saltmarsh sparrows have so far found the species at only one of those sites. This rapid local decline can likely be attributed to degradation of habitat for a variety of site-specific reasons. Overall, other plant species such as common reed (Phragmites australis), an aggressive invasive, and groundsel tree (Baccharis halimifolia), a native upland shrub, have quickly taken over areas once abundant with salt hay which has degraded quality saltmarsh sparrow habitat in a very short amount of time.
As part of the NJ Meadowlands’ Wildlife Action Plan, MRRI has made it a top priority to create, restore, and protect Saltmarsh Sparrow habitat within the Meadowlands District. Using the Atlantic Coast Joint Venture’s Saltmarsh Sparrow Habitat Prioritization Tool as well as historical and current avian survey data, we have identified the sites with the highest potential to restore and create quality high marsh habitat. Although management decisions must be made on a site-specific basis, our overall objectives are to:
- Assess and adjust hydrology in a way that allows for maximum re-colonization of salt hay and saltmarsh cordgrass where possible;
- Actively manage invasive common reed in high potential high marsh areas; and
- Build a framework for other entities to apply successful recovery strategies on larger scales.
Below is a short discussion of each proposed recovery site with regards to historical and current saltmarsh sparrow occupancy as well as potential management to support this dwindling local population.
Riverbend Wetland Preserve and Fish Creek Marsh are located at the southern extreme of the Meadowlands District directly along the Hackensack River. Riverbend itself is the most pristine high marsh in the district and is the last known site occupied by breeding Saltmarsh Sparrows. Even still, this high quality habitat, primarily dominated by salt hay, shrinks every year due to the steady colonization of common reed which the sparrow population has directly responded to. In the 2017 breeding season, a minimum of 4 pairs were present in this relatively small but highly productive high marsh habitat. During the 2021 Breeding Bird Atlas, just one pair was observed exhibiting breeding behavior. To restore this habitat to its former productivity, MRRI biologists will be investigating various methodologies (without use of herbicides) to stop the spread of common reed and ultimately limit its ground cover as much as possible. Whether this can be accomplished through mechanical removal of common reed altogether or through a manual change in hydrology will be investigated. Similar management techniques are likely applicable to Fish Creek which hasn’t hosted Saltmarsh Sparrows since 2014 likely due to its far smaller size compared to Riverbend.
Harrier Meadow, located on the western edge of the district, has long been considered one of the crown jewels of the Meadowlands from a wildlife standpoint. Its avian diversity alone was nearly unrivaled for almost 20 years following the restoration of the site in 1997. As part of the restoration, two tide gates were installed which allowed for a limited flow of the tide in and out of the wetland, allowing many high marsh plants including Spartina and other grasses to thrive in the interior of the site. However, when Hurricane Sandy struck the coast of New Jersey in 2012, much of the public access areas of the neighboring Richard W. DeKorte Park were destroyed. The walking trails in this iconic park in Lyndhurst were extremely popular among nature enthusiasts and therefore had to be repaired. One of the most damaged trails was the Sawmill Creek Trail which runs generally parallel to the eastern boundary of Harrier Meadow. When the trail was restored, it was built higher and, as a result, now limits tidal flow to Harrier Meadow and changed the overall site hydrology. This has allowed groundsel tree to gradually take over areas once abundant with salt hay. The last record of breeding Saltmarsh Sparrows at this site is from 2019 with just one pair. To restore Harrier Meadow’s high marsh habitat, tidal flow west of the Sawmill Creek Trail must be restored by either building bridges along the trail or placing a series of box culverts.
Marsh Resources Meadowlands Mitigation Bank is a restored wetland located along the Hackensack River on the north side of the district. Before restoration, this site was a wasteland of dredge material. It is now a haven for a wide variety of wildlife species thanks to its high diversity of wetland habitat types from cattail marsh to low and high marsh. Saltmarsh Sparrows were documented here as recently as 2018 along with the only known pair of Seaside Sparrows (Ammospiza maritima) in Bergen County. Visits undertaken during the 2022 season revealed that cattail (Typha spp.) encroached on areas once more abundant with Spartina, suggesting that the water is becoming fresher in some parts of the site. Additionally, access to areas further from the road has grown increasingly difficult over time. Many of these challenging areas are at least known historical sites of saltmarsh sparrow breeding activity. Therefore, it is difficult to be sure that the species is totally absent from MRI. Regardless, the salt marsh habitat at this site appears to be changing into a more brackish and freshwater dominated wetland. At this time, it is not known if any techniques can be undertaken to restore and/or preserve these areas.
Additional Sites: Using the ACJV’s Saltmarsh Sparrow Habitat Prioritization Tool, MRRI biologists identified sites with no known records of Saltmarsh Sparrow presence but with high potential for habitat creation. Most of the areas identified already have small patches of salt hay which likely indicates that these sites have the proper hydrology to support larger areas of high marsh. Though it is unlikely that habitat can be created at all of these sites, investigations will be undertaken to determine what might be able to be accomplished. Assessments of present hydrology, elevation, and vegetation communities will be completed to make the soundest decisions to recover this small but important population. Additionally, the different management techniques undertaken here in the Meadowlands to preserve, restore and potentially create additional Saltmarsh Sparrow habitat will help to inform others and support the overall effort to save this disappearing iconic Atlantic Coast species.
References
Hartley, M.J. and A.J. Weldon, eds. 2020. Saltmarsh Sparrow Conservation Plan. Atlantic Coast Joint Venture, acjv.org/documents/SALS_plan_final.pdf