Without intervention, the saltmarsh sparrow – the only bird species that breeds solely in the salt marshes of the Northeast United States – could face extinction due to rising seas.
Saltmarsh sparrows spend their entire lives in coastal salt marshes along the United States Atlantic and Florida Gulf coasts. The sparrows breed in all coastal states from Maine south to Virginia, and spend their winters from the southern portion of the breeding range south to Florida.
While the species still occupies the majority of its historical range, the number of individuals within the breeding range has significantly declined. More than four out of every five saltmarsh sparrows have disappeared since 1998 – an estimated population decline of 87%.
The U.S. Fish and Wildlife Service is reviewing the status of this species and in 2024, will make a determination of whether or not the saltmarsh sparrow warrants protection under the Endangered Species Act.
Saltmarsh sparrow populations are declining due to historic losses and degradation ofhabitat, as well as accelerated sea level rise across Atlantic Coast salt marshes. High tides and storm surges are increasingly flooding saltmarsh sparrow nests and their high marsh habitat. When nests flood, chicks may drown or eggs may float away. Low reproductive success is the primary reason the saltmarsh sparrow population continues to drop. Sea level rise is now the primary threat to saltmarsh sparrow and their high marsh habitat.
In coordination with the Atlantic Coast Joint Venture, a partnership of state, federal, non-governmental organizations and academic institutions that work across the sparrow's range, we are planning and implementing substantial and innovative work to conserve saltmarsh sparrows and coastal marshes.
Partners include the academic consortium Saltmarsh Habitat and Avian Research Program, the USDA-Natural Resources Conservation Service, the U.S. Army Corps of Engineers and various state and federal agencies that are focused on transportation, wildlife and coastal zone management. Techniques to restore tidal flow and increase marsh elevation include removing or upgrading defunct structures, modifying ditches and berms to improve hydrology and adding sediments from dredged waterways to the marsh surface.
Landmark documents – the Salt Marsh Bird Conservation Plan and Saltmarsh Sparrow Conservation Plan – have been developed by the Atlantic Coast Joint Venture to outline specific actions that land managers can take to mitigate the effects of sea level rise on nest success, as well as other threats, like historical and current land development.
Saltmarsh sparrows are habitat specialists that only live in the tidal saltmarshes of the Eastern Coast of the United States. The birds nest in the highest elevation and least-frequently flooded portions of tidal marshes. Adults and fledglings forage in the low marsh and the fringes of channels and pannes, which are depressions in thethat retain water. Adults seek cover on the upland edge in shrubs or common reed (Phragmites australis) during storm events and floods. In their wintering range, they are primarily found in Spartina marshes.
The land near a shore.
Saltmarsh sparrows forage in a range of marsh habitats. During the breeding season, their diet consists of insects, amphipods and spiders. Nestlings feed only on insects. Immediately following the breeding season, smooth cordgrass (Spartina alterniflora) seeds are added to the diet. Their diet during winter is unknown, but is thought to consist mostly of seeds.
While saltmarsh sparrows search for food and spend the non-breeding season in different areas of the marsh, they only nest in the highest-elevation, least-frequently flooded portions of high. Nesting higher above the marsh surface, or closer to the upland edge, can attract attention of predators, while nesting closer to the marsh surface, or the frequently flooded marsh zone, increases nest threat. Female sparrows will adjust the location of their nests in response to these competing pressures, moving lower following predation or higher following flooding. While the birds are adapted to what would have historically been typical floods during monthly lunar tides and storm events, they are not adapted to increasingly prolonged flooding and higher water levels from rising seas and more frequent storms.
Saltmarsh sparrows are a medium-sized sparrow, similar in shape to a song sparrow, but with a shorter tail.
Length: 4.7 to 5.1 in (12 to 13 cm)
Wingspan: 6.5 to 7.7 in (16.5 to 19.5 cm)
With an average weight of 0.6 to 0.8 ounces (17.1 to 24.1 grams), saltmarsh sparrows weigh about the same as eight pennies!
The saltmarsh sparrow has rust-colored wings, a vivid orange-buff face and gray plumage with black stripes.
Nesting typically occurs from May through early September. Saltmarsh sparrows breed from Maine to Virginia, and winter from North Carolina to Florida. Hatching takes place 12 days after egg-laying concludes, and the entire nesting cycle from first egg to fledging is from between 23 and 27 days. Fledging can occur as early as eight days after hatching.
A typical female saltmarsh sparrow will lay four eggs a year. Young sparrows hatch featherless and blind, and require parental care. After nine to 10 days, they are feathered, vision is enabled and they are mobile. The fledglings apparently do not stay together after fledging. Females range up to 2.6 acres as they search for food, and then return to multiple locations to feed the young.
Records show that male saltmarsh sparrows live up to 10 years and females live up to six years.
Individuals breed for the first time during the following summer after fledging. Females mate with multiple males, and they are the sole nest builders and caregivers for the fledglings. When nests fail due to flooding, predation or other causes, females re-nest up to three times per breeding season. Nests are constructed in the high marsh where inundation occurs monthly during spring tides. They are placed just several inches above the marsh surface in saltmeadow cordgrass (Spartina patens), black rush (Juncus gerardii) or smooth cordgrass (S. alterniflora). Nests are typically situated above dense thatch, have woven grasses above the nest, or a combination of the two.