A Saltmarsh Sparrow at Jacobs Point in Warren, Rhode Island. Photo: Evan Lipton

Science

The Saltmarsh Sparrow Is Creeping Dangerously Close to Extinction

The bird’s survival hinges on the ocean, but rising waters and shrinking habitat are causing populations to plummet—with no clear solutions.

It’s first light, and the sky against the Connecticut coast is silky and pale. Two scientists stand ankle-deep in the marsh, stringing up nets in hopes of catching a ghost.

Chris Elphick, a conservation biologist at the University of Connecticut, strides through the coarse grass to meet them. Suddenly, he stops in his tracks.

He’s spotted our specter.

“There! There’s a bird sitting up on that stick,” he says, motioning to a palm-sized, orange-faced Saltmarsh Sparrow about 50 feet away. Dozens of these birds are probably hiding around us, but the sighting still feels lucky.

The Saltmarsh Sparrow, one of two species formerly known as the Sharp-tailed Sparrow, is rarely seen at eye level. The quiet, rusty passerine blends in with the grass, where it spends most of its days gathering and feasting on insects. In spring, the bird spins its cup-shaped nest near the highest part of the estuary, inland from where the marsh turns to ocean. Because the grasses are so low, finding a suitable spot for the nest can be tricky: The site must be steep enough to escape high tides, but shallow enough to avoid the sight of predators. Soon enough, three to five brown-flecked eggs appear—but the hard part has only just begun. The mother bird needs to know the daily pattern of the tides: If the water flows into her nest, her unhatched young will float out and away. The sparrows are used to sacrificing a few eggs; but over the past two decades, the sea has grown more treacherous, leaving many chicks helpless against the ocean and its whims. 

The sparrows' nests often flood during extreme high tides, which occur around the new and full moons. The flooding events are becoming more frequent as climate change causes ocean levels to rise. Photo: Jeanna Mielcarek

The species resides along the Eastern Seaboard year-round, but only breeds on a thin sliver of coastline between Maine and Virginia. For decades, the incursion of roads, beachside homes, and invasive plants have devoured its natural habitats—yet swelling sea levels may be its biggest enemy yet. Ocean levels on the East Coast are rising between 2 and 6 millimeters each year as a result of climate change, and according to most recent estimates, the bird’s population could plummet from 53,000 to 5,000 within the next 25 years. The sparrow is already on many state watch lists, and is labeled as “vulnerable” on the International Union for the Conservation of Nature’s (IUCN) list of threatened species. New research released in Conservation Biology on Friday posts an even more dire outlook: In 50 years or less, the species may be completely extinct.

“This is a little piece of biological diversity, of life, that is just going to disappear and will be gone forever,” Elphick says. The Saltmarsh Sparrow could be among the birds wiped out by humans, much in the same way the Dusky Seaside Sparrow was 30 years ago.

Hammonasset Beach State Park in Madison, Connecticut, is one of the many SHARP survey sites on the East Coast. Photo: Jeanna Mielcarek

In Search of a Ghost

The Saltmarsh Sparrow has always played hard to get. Birding legend Jonathan Dwight knew how to track the species by sight and song, and still struggled to find a nest in 1896. He had spent the better part of two decades collecting bird eggs, many of which were eventually housed in the American Museum of Natural History. Despite his expertise, he found the species to be vexing, eventually blaming his failure to unearth a single nest on the birds’ “exasperating shyness,” as he wrote in The Auk.  

Elphick has had better luck—with fewer sparrows. Here at Hammonasset Beach State Park, he’s headed up surveys for birds and nests since 2002. The summer of 2009 was one of the harshest due to relentless storms that carried away eggs and drowned chicks; of the 200 nests his student found that year, only five produced young. Counting the casualties isn’t so pleasant, but it’s the only way to know the repercussions, Elphick says.

Chris Elphick and his survey team marks a Saltmarsh Sparrow chick with an ankle band. By keeping tabs on the birds' survival rates and numbers, they can not only track the population health of the species, but also of salt marshes up and down the coastline. Photo: Jeanna Mielcarek

On this particular morning, Elphick and University of Connecticut researchers Samantha Apgar and Kate Ruskin are trapping sparrows as part of a larger effort to monitor the health of saltmarsh-reliant species on the East Coast. The process is similar to other banding operations: catch the birds in nets, take measurements and notes, and then tag them with slight, numbered anklets for future monitoring. But unlike most passerines, this species needs to be flushed. To keep the birds from getting agitated, the team plans to move quickly. Ruskin instructs Apgar, who is new to the team, to begin fanning out toward the nets they rigged up earlier. “Let’s just zigzag and clap," Ruskin says. "Feel free to run if you see a bird." 

As soon as Ruskin spots one she takes off—as fast as her rubber boots can take her. Apgar circles around to corner the bird, and Elphick throws off his hat and swoops in from the other side. The sparrow leaps . . . straight into the net. “That’s how it’s supposed to work,” Elphick says. The researchers work through the rest of the morning, but only catch a half dozen Saltmarsh Sparrows in all. 

Anticipating Extinction

Elphick isn't alone in his struggle: He's part of a scientific task force that spans that Atlantic coast, collecting data for the Saltmarsh Habitat and Avian Research Program (SHARP). Mo Correll, a postdoctoral researcher with the University of Maine and a landscape ecologist at the Bird Conservancy of the Rockies, is one of his dedicated collaborators; she’s spent the past six years trekking to obscure tidal marshes to count birds for SHARP. After combining her observations with historical data dating back to 1998, she discovered that Saltmarsh Sparrow populations were shrinking by a staggering 9 percent each year. Correll’s latest research looks at four other bird species from the marsh, but shows that the sparrows are by far the most imperiled.

The new Conservation Biology study, which Correll helped author, also found that infrastructure near the coast, such as roads and rail lines, may be largely to blame for the population decline. These man-made thoroughfares unintentionally become barriers against the tide and keep sediment from building up in the marsh. Any resiliency the marsh once had against sea-level rise is slowly being erased. 

It’s still unclear where the solution lies. Millions of dollars have been spent rebuilding tens of thousands of acres of coastal wetlands, but research shows these efforts have done nothing to boost the sparrow’s populations. A study authored by Elphick last year found that many restoration efforts, particularly those in low-lying marshes, have failed to create more suitable nesting habitats. This is partly because the projects focus on conserving vegetation, not the sparrows. Many of them consist of removing invasive grasses, with the expectation that native salt marsh species will return on their own. But these efforts pay little attention to whether the grasses the sparrows nest in are growing at suitable elevations, or whether they're even growing at all.

Two fledgling Saltmarsh Sparrows at Hammonasset with a fledgling Seaside Sparrow in between. Seaside Sparrows are also highly specialized to tidal marshes; as the habitat declines, so do they. Photo: Jeanna Mielcarek

One way to build up the marshes’ resilience may be to manipulate manmade barriers without removing them completely. Elphick imagines having a controlled tidal system during the breeding seasonone that keeps water from rushing in during the highest monthly tides, but allows sediment to build up naturally. That sort of project would be difficult to enact, Elphick admits: Scientists, agency officials, and eventually the public would all have to buy into it.

Also at the top of the list: persuading the IUCN to upgrade the bird’s status to “endangered.” It’s possible that the group will make a move this year, says Patrick Comins, director of bird conservation for Audubon Connecticut, who's leading the charge. “I think it’s going to happen,” he says. “I think [Elphick] and his SHARP team’s numbers are solid enough that it won’t be much question that this bird deserves to have a lot of conservation focus on it.” A status change could give ecologists the ammunition they need to buffer salt marshes from future housing or infrastructure development. It could also help bring in new research dollars.  

Amid the uncertainty, the scientists carry on. The SHARP surveys and tagging run through the summer, and continue in the fall with new technologies, such as nanotags for tracking the birds. Back at Hammonasset, Ruskin and Apgar are taking measurements of a sparrow’s bill and plumage, information that lets them study the birds' evolution and hybridization with other species. As soon as they’re finished, Elphick takes the bird, combing through its tail feathers to show me the ones that have worn away. They’ll all look this way by summer’s end, he says, from the sea salt and friction of fleeing through the grass.

The feathers will regenerate before the next breeding season—just one of the many signs that this bird is equipped to deal with adversity. But it’s unclear whether resilience is enough here. Another high tide, another flood, and only time will tell. 

“The views expressed in user comments do not reflect the views of Audubon. Audubon does not participate in political campaigns, nor do we support or oppose candidates.”