Saltmarsh Sparrow May Find Itself In Harm’s Way

Global warming could threaten dependency on local coastal habitat

The loss of habitat is a threat to the existence of the saltmarsh sharp-tailed sparrow, according to a report released by the Connecticut Audubon Society.

Though perhaps not as dramatic as polar bears drowning in rising Arctic seas and melting ice, the perils of a little sparrow that depends on the salt marshes of southeastern Connecticut for nesting could be a local indicator of the effects of global warming. In the Connecticut State of the Birds 2008 report released last week by the Connecticut Audubon Society, the saltmarsh sharp-tailed sparrow is named among six threatened species that depend on specific types of habitat in Connecticut for their survival.

“This could be the first Connecticut species to go extinct if sea levels continue to rise as they are,” said Milan Bull, senior director of science and conservation at the Audubon Society. “With global warming and sea-level rise increasing, our coastal salt marshes are at great risk, very great risk.”

The saltmarsh sharp-tailed sparrow, a migratory species that spends May through November in the marshes of southeastern Connecticut, is “arguably the bird for which conservation actions in Connecticut are most important in terms of ensuring long-term survival,” the report states.

The specialized habitat requirements of the brown, white and copper-hued bird make it particularly vulnerable as sea level rises and marshes flood more frequently.

Roughly half of the species’ worldwide population lives in southern New England, and most of those are concentrated along the eastern Connecticut coast, at marshes on Great Island in the lower Connecticut River in Old Lyme; at Hammonasset State Park in Madison; the Hammock River estuary in Clinton; and at Barn Island Wildlife Management Area in Stonington, among others.

Because of heavy development along the coast, the marshes can’t spread inland, Bull said. The sparrows build their nests on the high marsh, amid dense stands of saltmeadow cord grass, smooth cord grass and black rush about two to three feet high. When the high marsh floods from heavy rains or an unusually high tide, the nests can flood and eggs are lost.

Over the last 30 years, sea level has been rising about 4.4 millimeters — roughly two-tenths of an inch — per year, according to records from a Thames River tide gauge maintained by the National Oceanic and Atmospheric Administration. High tide on the river now averages 6 inches higher than in 1980, and the rate of rise is faster than the previous 150 years.

Maggie Jones, executive director of the Denison Pequotsepos Nature Center in Mystic, said she’s seen the sparrows on Barn Island. She described them as “very nondescript, secretive little birds, not at all showy. Nor do they have a strong song.” They eat a variety of insects and seeds.

A recent expansion of the state-owned Barn Island preserve, she noted, helped protect critical habitat for these birds, and more such efforts are needed. Restoration and recreation of salt marshes that can withstand sea level rise, she said, is essential to the long-term survival of not only the saltmarsh sparrow, but many other species of birds, juvenile fish and other wildlife.

“Save the salt marsh, save the sparrow. Save the sparrow, save the salt marsh,” she said.

The state DEP lists the bird as a “species of special concern.”

According to the Audubon report, the population is estimated at about 10,000 birds in Connecticut, but “it is widely assumed that saltmarsh sharp-tailed sparrows have declined” as up to 80 percent of historic saltmarsh areas have been lost due to development. Currently two professors from the University of Connecticut’s Department of Ecology and Evolutionary Biology, Chris Elphick and Margaret Rubega, are studying the sparrows to get a better estimate of the numbers, what factors cause nesting success and why the sparrows prefer certain marshes.

The Audubon report advocates the state increase its efforts to protect remaining salt marshes, and enact management practices that specifically target high marsh habitat.

“It is clear that rising sea levels cannot be ignored, and that protecting species dependent on coastal marshes will require some imaginative and potentially controversial conservation work,” the report states. “The sooner we begin to think about how, and even whether, this problem can be solved, the better prepared we will be once current research (into the magnitude of the threat from sea level rise) is completed.”

Other species highlighted in the report as being “in serious trouble” because of habitat loss are: the bobolink, which depends on grasslands; the blue-winged and the golden-winged warblers, which depend on shrub lands; the American Oystercatcher, which lives in coastal areas; and the cerulean warbler, which lives in mature forests and was called the fastest declining of all Connecticut’s songbirds.

http://ctaudubon.org