The black rail has been a rare bird in New Jersey for decades, but now the shy, small bird of the high marshes is even more difficult to find.
Sea-level rise and historical human disturbances are destroying its nesting habitat, according to researchers who recently completed a field study of the species.
Damage to the high marsh means more flood damage for human neighborhoods, said David Mizrahi, vice president for research and monitoring for New Jersey Audubon’s Center for Research and Education in Cape May Court House.
“Marshes are natural buffers to wave and storm action,” Mizrahi said. “Losing species like the black rail, and high marsh habitats or thousands of acres of marshland because of sea-level rise, is a sign of more difficult times ahead for us. You lose marshes, you lose communities.”
The marsh at the end of Jakes Landing Road in North Dennis Township is a beautiful birding hot spot, owned by the state.
But it has lost much of its high marsh to land subsidence and sea level rise in recent years, said CMBO Director David LaPuma.
High marsh is characterized by the native grass spartina patens, or salt hay, he said. Low marsh is dominated by spartina alterniflora, which can handle a wetter environment.
Areas where black rail used to be heard regularly are now inundated, and black rails can no longer nest there, he said. There is just one area back by the tree line where black rails have been heard in the last few years.
“But historically we used to hear them in front there,” he said, sweeping his arm in an arc across the marsh.
New Jersey Audubon, the state Division of Fish and Wildlife and the Conserve Wildlife Foundation of New Jersey recently completed a three-year field study of the black rail population that found evidence of the birds in only 7 percent of the 376 locations studied.
Audubon citizen scientists and Fish and Wildlife consultants went out at night, played audio of the birds’ calls and waited to hear a response, Mizrahi said.
A field study in 1988 by well-known birders Paul Kerlinger and Clay Sutton found them at 26 percent of 65 locations surveyed, according to N.J. Audubon. That was considered a poor showing, according to an article in N.J. Audubon magazine by Research Project Coordinator Mike Allen and Senior Research Scientist Nellie Tsipoura.
Since then, researchers estimate the black rail has declined by another 75 percent along the Atlantic Coast. The Eastern Black Rail Conservation and Management Working Group, led by The Center for Conservation Biology, says the black rail “may be the most endangered bird species along the Atlantic and Gulf Coasts of North America.”
Other species suffering from loss of high marsh to nest in include the saltmarsh sparrow and the state-endangered northern harrier, a bird of prey, Mizrahi said.
Black rails are often heard but not seen, even by the most experienced birders, he said.
“They behave more like mice than birds,” he said. “They follow rodent trails through marshes. They are unique and enigmatic.”
They are the size of sparrows, while the easier-to-see clapper rail is the size of a chicken, Mizrahi said.
Mizrahi said that historically poor coastal management from decades ago has caused much of the high marsh damage.
“In mosquito control, a linear ditch technique was used for decades,” said Mizrahi, in which grids of straight ditches were dug to get to and kill mosquito larvae. “That brought tide water much deeper into high marsh zone.”
Even the open marsh water management used today brings tide water deeper into marshes, he said.
Most black rails found in 2015-16 were in northern Cape May County and southern Atlantic County around the Great Egg Harbor and Mullica rivers, Mizrahi said.
“Not so much in Cumberland County or on the Delaware Bayshore, where most detections were in 1989 (along with the Great Egg Harbor River),” he said.
Mizrahi said studies are also being conducted in Maryland, Virginia and South Carolina, and the U.S. Fish and Wildlife Service is doing a status assessment that might support a federal listing as endangered or threatened.
It is listed as threatened in New Jersey.