The race to reverse the saltmarsh sparrow's decline

In the tidal wetlands of the Delmarva peninsula, a small bird holds onto a tenuous existence. The saltmarsh sparrow has adapted to a life hopping around on soggy ground, depending almost entirely on a plant called salt meadow hay, or Spartina patens. This grass forms swirling cowlicks that qualify as “high” marsh by rising inches above the flat expanse of the low marsh, which floods more often. The high marsh still floods, but only occasionally, so the saltmarsh sparrow nests there, evading land-borne predators while employing a bag of tricks to survive the tides.

“Their nest cycle fits perfectly within a lunar cycle, which is just fascinating to me,” said Hen Bellman, coastal program manager for Audubon Mid-Atlantic. “So as soon as the tide is low enough to start nesting, they lay their eggs, they incubate the eggs, hatch, and then hopefully the chicks fledge before the next lunar cycle begins.”

If the water does reach a saltmarsh sparrow nest, tucked into the patens, the eggs can simply float and remain viable. And before they learn to fly, the juveniles know how to climb the grass to avoid getting washed away.

“They'll climb to the highest point in the grass and just hang out there as the tide is going,” said Chris Guy, coordinator of the Habitat Goal Implementation Team for the Chesapeake Bay Program. “But if you have that nuisance tide that goes higher than that, they drown.”

With climate change, not only is the Chesapeake Bay experiencing some of the fastest rates of sea level rise, but the highest high tides are becoming more extreme. Once a patch of marsh grass is completely submerged, or lost permanently, even the saltmarsh sparrow’s adaptations can’t save it. And the species never nests at higher elevations, where tall shrubs and invasive phragmites reeds might be hiding predators. It’s a specialist trapped in a shrinking band of habitat.

“You have sea level rise that wants to push them up further in the high marsh for nesting, and then you have the phragmites invasive species trying to push them down in the marsh,” Guy said. “That combination of stressors has really shrunk their functional habitat, and their ability to be successful in nesting.”

As a result of the squeeze, saltmarsh sparrow populations have been declining by 9% yearly since 1998, according to the U.S Fish and Wildlife Service (USFWS). In Maryland, which holds 25% of the entire population, there were estimated to be 15,100 birds living in 2011/2012. If such a rapid decline continues, the saltmarsh sparrow might be extinct by 2050. But a concerted restoration effort has already begun.

Stitching together coastal marsh habitat

Efforts on Maryland’s Eastern Shore and across the East Coast are focused on improving nesting habitat for the saltmarsh sparrow. Population monitoring has continued for decades, using a survey protocol developed by researchers with the Saltmarsh Habitat and Avian Research Program (SHARP). In 2020, the Atlantic Coast Joint Venture, a broad partnership of state and federal wildlife agencies and organizations focused on coastal marsh habitat, drafted a conservation plan for the species. And agencies like USFWS have partnered with local governments and nonprofits to initiate on-the-ground restoration projects.

“I had realized that this was one of the most special bird conservation issues in the state (because we have such a large extent of salt marsh for our state’s small size) and so jumped on the opportunity to carry out the SHARP surveys and learn more about the salt marsh birds here,” said David Curson, president of Audubon Mid-Atlantic, in an email. “We weren’t focused on the sparrow but on the tidal marsh ecosystem and its entire bird assemblage.”

Curson and Audubon started the Blackwater 2100 project in 2011, partnering with The Conservation Fund and USFWS staff at Blackwater National Wildlife Refuge in Dorchester County, Maryland, to create a sea level rise adaptation plan. It resulted in management efforts focused on improving marshes that were at risk of being lost. One project involved removing dead trees in a ghost forest at the refuge, to help facilitate the natural process of marsh migration—giving a marsh the room it needs to rise in elevation, shifting upward into undeveloped land. Another created an extension of a tidal creek that improved drainage in a waterlogged portion of Farm Creek Marsh. And managers used thin-layer placement of dredged material to successfully raise the elevation of 35 acres at Shorters Wharf by spraying the muddy slurry over the subsiding marsh.

More recently, Audubon has initiated a program called Marshes for Tomorrow in partnership with the Delmarva Restoration and Conservation Network, to establish a restoration plan for 25,000 acres of Maryland salt marshes.The plan’s main target is the saltmarsh sparrow, with benefits extending to the entire marsh ecosystem.

“Marshes provide a lot of ecosystem services, including nursery habitat for commercially important fish (including fish that when grown move into the open Chesapeake Bay), a physical buffer against storm surge for nearby property, and a place for recreation, such as fishing, boating and wildlife watching,” Curson said.

Under Marshes for Tomorrow, Audubon has turned its attention to Deal Island in Somerset County, where a more ambitious method of using dredged material has reshaped the landscape. In 2023, the U.S. Army Corps pumped 168,000 cubic yards of sediment from the Wicomico River as part of its usual dredging efforts that keep shipping channels clear for traffic. But this sediment was pumped nine miles to Deal Island Wildlife Management Area, where instead of a thin layer, 120,000 acres of material was applied to a target area of 72 acres in order to rapidly create high marsh habitat.

“I believe this was the first time in Maryland that saltmarsh sparrow habitat needs had informed the design of a Corps beneficial-use project,” Curson said. “Audubon established the target elevation of this project using local tide data and the nesting ecology of saltmarsh sparrow.”

The project area resembled a bare moonscape when dredging was completed in December 2023. Since then, contractors planted over 300,000 plugs of native grasses, including patens as well as salt grass and smooth cordgrass. By the following summer, waves of lush grasses had already filled in much of the site, with still more to be planted.

Audubon is assisting with another project that will break ground a few miles away in Somerset County, at Irish Grove Sanctuary, owned by the Maryland Ornithological Society. The sanctuary protects part of a salt marsh that supports many of Maryland’s remaining saltmarsh sparrows. In parts of the marsh, workers will improve drainage and enhance vegetation by digging artificial runnels—the winding channels that give a wetland the appearance of a network of blood vessels when seen from the air.

“That's the technique of trying to get marshes from being too flooded, too much so that we can bolster the population,” Guy said.

In 2025, under Marshes for Tomorrow, Audubon will also begin reaching out to private landowners in priority areas of Delmarva, to expand their wetland restoration efforts beyond public lands and preserves.

In coming decades, additional efforts will include large-scale island restoration at James and Barren islands in Dorchester County, which were once strongholds for the saltmarsh sparrow. The islands have all but disappeared, but are slated for restoration by the Army Corps, succeeding the reconstruction of Poplar Island in Talbot County.

“And then the final strategy is actually retreat,” Guy said. “The idea is to create corridors that allow things to move backwards as the marshes move backwards.”

If a marsh is hemmed in by developed land, it has nowhere to migrate to as waters rise. But by protecting adjacent forests, marsh migration corridors will allow those uplands to one day become wetlands.

“The marsh migration corridors are the place where we have the most hope,” Guy said.

As the new marsh plants take root, the positive impact of current efforts may be several years away. But the goal is to keep the total saltmarsh sparrow population above a threshold of 25,000 birds. Though the saltmarsh sparrow is currently on pace to land on the endangered species list, no one wants to wait that long to take action to save it from extinction.

“The listing takes years,” Guy said. “We would like to restore the population before it needs to be listed.