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    Imminent Horizons
    Sunday, June 23, 2024

    One bird’s troubles show the story of rising seas in salt marshes

    A saltmarsh sparrow (on the right) and a Nelson's sparrow on the left. (Photo courtesy of University of Connecticut biologist Chris Elphick.)
    A metal culvert allows water to flow in and out of the salt marsh at Barn Island Wildlife Management Area in Stonington. (Photo by Nolan Adis, University of Connecticut)
    A metal culvert allows water to flow in and out of the salt marsh at Barn Island Wildlife Management Area in Stonington. (Photo by Nolan Adis, University of Connecticut)
    The salt marsh at Barn Island Wildlife Management Area in Stonington. (Photo by Nolan Adis, University of Connecticut)

    Editor’s note: This story was reported by students in the University of Connecticut’s environmental journalism class, led by Professor Christine Woodside, an environmental writer and former Day reporter/editor. Students who contributed to this story are Nolan Adis, Sonia Ahmed, Rebeca Marin, Emily Markelon, Deanna Martin, Erica Yirenkyi and Anna Zimmermann.

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    In the coastal marshes of southeastern Connecticut, as sea-level rise brings more frequent flooding, one brownish-yellow bird that lives only in salt marshes is fighting to survive.

    Since 1998, saltmarsh sparrows (Ammospiza caudacuta) have declined by about 87% in the United States. In 2012, they numbered about 60,000. Today, about 20,000 breed in marshes on the East Coast.

    The sea level across the sparrows’ range is projected to rise about 13 inches above the 1994-2014 baseline by 2050, according to the most recent estimates provided to NASA by the Intergovernmental Panel on Climate Change.

    Salt marshes ― grassy wetlands along the coast that are flooded periodically by salt water ― along the Atlantic coast used to flood about once a month. Now they are flooding higher and more often than about once a month.

    Saltmarsh sparrows begin breeding around the new moon of early May. They lay their eggs in the marsh grass on the gamble that the eggs will incubate before the next tidal flood. Their eggs can wash away and chicks can drown before they are large enough to fly.

    Saltmarsh sparrows’ struggles prove that marshes, which provide a buffer between water and land, are changing. A salt marsh holds many great features, from their sediments located underneath it which holds mineral matter, to plants special to their environment.

    Normally as the sea level rises, marshes would migrate inland, but in many areas today, they can’t, because buildings, streets and railroad tracks are in the way.

    The Fish and Wildlife Service will decide this year whether to list saltmarsh sparrows on the federal endangered species list. In Connecticut, they are classified as a species of special concern.

    They breed from coastal states from Maine south to Virginia and spend their winters in southern Florida. A regional consortium of scientists is working to stabilize their population.

    The drama of a struggling species shows in the extensive high marshes of Barn Island Wildlife Management Area in Stonington. Since 2002, Chris Elphick, a conservation biologist and professor at the University of Connecticut, has been studying the birds’ decline there.

    He began these studies after hearing from conservationists in the town of Guilford, who observed saltmarsh sparrows’ nests flooding there.

    Elphick said the saltmarsh sparrows are struggling as marshes change up and down the Atlantic coast, but that in Connecticut “it is as bad as it gets.”

    The flooding and rates of change are most dramatic here.

    The chaotic life of the saltmarsh sparrow

    In many ways, saltmarsh sparrows already live chaotic lives. Males and females mate with multiple partners, which is unusual among birds. Females make nests right in the marsh grasses in between times the sea floods. The hope is that the eggs will hatch and chicks gain some strength before the tide comes back in. But frequently, the eggs wash away or the chicks drown. Saltmarsh sparrows have shown signs of adaptation, from remaking their nests, to recollecting eggs that leave their nests.

    Elphick, along with UConn colleague Christopher R. Field and a group of scientists from several Northeast institutions including the Cornell Lab of Ornithology, published a study in November 2023. It found saltmarsh sparrow populations tend to be small, localized and struggle to recover from disturbances like floods or bad storms. The scientists found that development isolates populations of these birds, affecting their abilities to maintain genetic diversity. They wrote that restoring marshes by improving water flow in and out of them will be crucial for the birds’ survival.

    Elphick said that saltmarsh sparrows are among the first to be affected by climate change: The sea rises right into their homes. So looking at their struggles can help humans understand how climate change is altering the landscape.

    Human alterations to marshes

    Barn Island is a 1,024-acre salt marsh that humans have been altering for almost a century. The state of Connecticut bought most of this land in the 1940s to provide healthy undisturbed habitat for fish, birds, mammals, and other wildlife. The area encompasses coastal forest, salt marshes, and open water of Little Narragansett Bay.

    Humans have altered salt marshes for centuries. From housing to transportation, to digging mosquito-control ditches, to harvesting saltmarsh hay, these actions have hurt the health of the high marshes.

    The town of Stonington dug ditches in 1931 to drain water and control mosquitoes. They quickly realized this affected water birds that needed insects. In the 1940s, state fisheries and game officials bought adjoining land and built dikes that flooded impoundments. That helped the water birds but changed the salt levels of the contained water. So invasive grasses such as tall Phragmites australis and cattails grew, removing some habitat for saltmarsh sparrows, which need high grasses.

    Managers then installed large culverts under the dikes, restoring salt water flow in and out of the marsh grasses, which helped encourage native grasses like saltmarsh cordgrass (Spartina alterniflora), salt meadow cordgrass (Spartina patens), and spikegrass (Distichlis spicata).

    A trail through Barn Island follows a dike that separates the high marsh from the extensive impoundments. These man-made structures form a sprawling grid within the marsh, delineating vast areas of Spartina alterniflora intersected by water channels flowing within these entrenched boundaries. These plants provide nesting, shelter and seeds for the birds.

    Over one-third of Connecticut’s tidal wetlands have been lost since colonial times to development. And the saltmarsh sparrow had already seen a major decline in the species between the 1990s and 2012. Since 2012 the population has since remained stable, but Elphick said that this could be “the calm before the crash” because the species has not recovered from that initial decline.

    Elphick guides graduate students for field work and monitoring. During breeding season, they tag birds with unique numbers, taking blood samples, measure them, and record locations of nests and vegetation.

    Just as Elphick is unsure about the future of the saltmarsh sparrow, he has his doubts about the future of conservation. “I lean towards the bleak,” he said, “but that’s my personality.”

    He added, “The main issue is not climate change. It’s human development. We are building over their habitats, and climate change becomes worse when it is in addition to those other things.”

    A regional effort to improve salt marsh habitats for the saltmarsh sparrows is under way. The Atlantic Coast Joint Venture, established in 1987 to restore native bird populations, turned its efforts to the saltmarsh sparrow and the marshes in 2016. Their goal is to stabilize the East Coast population at 25,000 birds, preventing a decline to the predicted 10,000 without salt marsh improvements.

    “We talk about the saltmarsh sparrow because they are particularly vulnerable to sea level rise,” said Mitch Hartley, the North Atlantic assistant coordinator for the Atlantic Coast Joint Venture. He said the shift to salt marsh preservation was because “there wasn't enough coordination in that space, and those are some of the most endangered species” living in these salt marshes.

    “We are telling the story of thousands through the story of one,” Hartley said.

    The Atlantic Coast Joint Venture and its partners have protected and restored over a million acres of land. Their work in salt marshes includes work to undo the damage of the old mosquito-control ditches, raising the height of land in marshes, working to allow some marshes to migrate inland, and “runnelling,” which is digging shallow micro-ditches to manage water flow and improve conditions for the sparrow.

    Hartley added, “Our role is modest, but I look at projects like that and I think my grandchildren are going to go to that marsh,” and without his work, they might not have been able to otherwise, Hartley said.

    Aimee Weldon, a USFWS staffer in Hadley, Mass., who coordinates the Atlantic Coast Joint Venture, said in one recent public presentation that the venture holds “100% of the global responsibility for conserving this species."

    She added, “We really had to be very strategic about how we chose our conservation priority so we that could really have a measurable impact in moving the conservation needle on something.”

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