Placing the Wrong Blame for the Black Rail Decline?

A small water bird, rare to begin with, is almost extinct in the Chesapeake Bay region, and scientists and managers reach a comfortable conclusion as to the cause of it's decline; Climate Change!

The elusive Black Rail

Black rail population sinking fast as rising sea level drowns its habitat - Federal endangered species status being considered for secretive bird of East Coast’s deep marshes

The sparrow-size bird lives deep in marshes that are hard to access, and it is most active in the wee hours of the morning. Even then, it tends to scamper through dense vegetation, rather than fly — some call it a “feathered mouse.”

“We know almost nothing about this species,” said ornithologist Bryan Watts, director of the Center for Conservation Biology in Virginia. “It’s very tiny and incredibly secretive. Even most bird watchers have never seen this species before.”

Now, even hearing their call is unlikely. Its habitat, a delicately balanced zone deep within coastal marshes, is being flooded by the rising waters. And the Eastern black rail is disappearing fast — potentially becoming the first victim of sea level rise around the Chesapeake Bay and other areas of the East Coast.

Watts recently completed an exhaustive review of literature about the black rail, going back more than 100 years. His findings on the status and trends of its rail population were compiled in a 148-page report released in 2016.

“They are sort of evaporating around us,” Watts said.

The decline has been rapid and unexpected. Only 50 years ago, part of Dorchester County on Maryland’s Eastern Shore was a world-renowned hot spot for birders seeking a glimpse of the elusive black rail. Today, the black rails are gone from Elliott Island, and only a handful are left in the state. None have been seen in Virginia’s coastal marshes for a couple of years.

Their exact number doesn’t make much difference, Watts said, because the downward trend is so strong — Maryland numbers have fallen 90 percent in just 25 years.

“This species is not going to be sustainable in its landscape in the face of sea level rise,” he said. “It will be lost. Maybe in five years, maybe in 10 years. But it’s on the way out.”

So let's looks at sea level in Maryland (again).

A slow steady rise of about 3 mm a year, about half of which is due to natural and man made land subsidence, and not increasing ocean volume from melting ice. No sign of acceleration over the past 100 years.

The bird is listed as endangered in both Maryland and Virginia, as well as several other states along the Atlantic Coast. The U.S. Fish and Wildlife Service is considering protecting it through the federal Endangered Species Act and is expected to make a recommendation in September 2018.

Historically, the black rail has received little attention. Along with its deep marsh habitat and nocturnal activity, the black rail is quite small. Its body is about 6 inches long, with dark feathers and white speckles on its wings, back and abdomen. It has brilliant red eyes. But hardly anyone sees it — even professional ornithologists.
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Black rails were once found from Texas up the East Coast as far as Massachusetts. Over time, they have suffered major habitat loss as marshes were buried to make way for urban growth. Places such as Cambridge, MA; Queens, NY; Atlantic City, NJ; and Baltimore once supported black rails. The historic ditching and draining of marshes eliminated more habitat.

And there's the real cause of the demise of the Black Rail, hidden in plain sight. Up and down the coast, marshes have been drained, or coastlines hardened in such way that the marshes dry up.

But scientists believe the recent, rapid demise of black rails is linked to rising water. Black rails live in high marshes that, with slightly higher elevation, typically escape the daily tidal over-wash. But the birds forage for invertebrates, such as water beetles, in areas that have wet soil or even a thin covering of water.

It’s a narrow band that Watts describes as a “hydrology tightrope.” With sea level rise, he said that he believes the nests are increasingly inundated by storms and unusually high tides. If a nest is ruined in a single year, the population can rebuild the next year. But if nests are drowned more frequently — and eggs along with them — the birds gradually disappear.

The birds can adjust by moving upslope but, because marshes are relatively flat, even a small amount of rising water can push them out of suitable habitat toward trees, roads or stands of invasive phragmites. “If the water gets up 2 centimeters, it is not just inundating the edge of the marsh, it is inundating the entire marsh,” Watts said. “Once it hits that tipping point, you are effectively flooding the entire marsh.”

However, marshes, given some place to go, rise with sea level. Sea level has been rising steadily since the end of the last ice age, and Black Rails either evolved recently, or thrived through some of the most rapid rises in sea level the world has ever seen:

In the Saxis Wildlife Management Area on Accomack Island on Virginia’s Eastern Shore, black rails were last located at the tree line, and then they were gone.

The decline has been rapid. In 1991–92, a DNR survey in Maryland’s portion of the Bay recorded 180 black rails. “We found more than we expected,” Brinker said. “They were widespread. It was the third most frequently encountered rail in the marshes of the Chesapeake Bay.”

In 2007, the DNR and the Center for Conservation Biology, which is affiliated with both the College of William and Mary and Virginia Commonwealth University, collaborated on a Baywide survey. They found just 50 calling males in Maryland and Virginia combined. “That was the first indication that we had that the population was collapsing,” Watts said.

Birders had been reporting a decline, Brinker said, “but the magnitude of the change sort of hit us in the face.” A 2014 survey found just 10 individuals — eight in Maryland and two in Virginia.

That makes it sound like something else happened. A new predator, a newly introduced disease (West Nile Virus perhaps?), but not a sudden change related to slowly changing shorelines and land uses.

The decline isn’t limited to the Bay. Black rails have largely disappeared at the northern edge of their range, with “catastrophic” rates of decline in New Jersey, Delaware and North Carolina, according to Watts’ status report, which was prepared for the upcoming federal endangered species review. South Carolina had a slower rate of decline, but still more than 4 percent each year.

According to Watts’ report, the total number of breeding pairs along the Atlantic Coast is between 455 and 1,315. Their status might be better in Florida and Texas, both of which have large amounts of potential habitat, but many of those areas have not been surveyed.

In those two states, “we have a huge amount of uncertainty,” Watts said.

Biologists, state and federal agencies are coordinating to conduct surveys in those and other areas in the next two years.

Historically, black rails were also found at some inland sites in the Eastern United States that simulated conditions found in high marshes, such as hayfields adjacent to river flood plains. But over time, most of those locations have also disappeared, largely because agricultural practices have intensified and altered the habitat, Watts said.

Black rails are also found in the Caribbean and in Central America, but little is known about their status.

Must We Abandon the Marshes to Save New Orleans?

A new study of the marshes around New Orleans suggests that the best way to save New Orleans from the "next Katrina" is to abandon the outer marshes, and focus on saving those closer to the city:

Mississippi River Mouth Must Be Abandoned to Save New Orleans from Next Hurricane Katrina

Extensive studies done after Katrina verified what lifelong residents of southeastern Louisiana already knew: Unless the rapidly disappearing wetlands are made healthy again, restoring the natural defense, New Orleans will soon lay naked against the sea (see satellite image, below).

So, how does one reengineer the entire Mississippi River delta—one of the largest in the world—on which New Orleans lies?

Three international engineering and design teams have reached a startling answer: leave the mouth of the Mississippi River to die. Let the badly failing wetlands there completely wither away, becoming open water, so that the upper parts of the delta closer to the city can be saved. The teams, winners of the Changing Course Design Competition, revealed their detailed plans on August 20. Graphics from each plan are below. . . 

 The river should be cut off (north of the number 5) to better
 save wetlands closer to the city (red “Sustainable” line), and the rest
must be left to wither away, becoming open water (brown “Historic” line).

The modern Mississippi Delta passed its "use by" date many years ago. The river wants to take a shortcut down the Atchafalaya waterway (6 on the map), and bypass the old crows foot delta, thereby robbing the delta of it's sediment source, and dooming New Orleans to becoming a sinking bywater.  The switching of the river has happened many times over in geologic history. The only reason to prevent it is because of New Orlean's importance as a seaport. This may well be another example of the "sunk costs fallacy."

Goose Population Sinking the Eastern Shore

An interesting article on the loss of marsh on Maryland's eastern shore to open water. 

We've seen how large areas of the eastern shore marshland have been reclaimed by open water, a process caused by rising sea level, subsiding land, and nutria.  However, a recent push to exterminate the nutria has all but eliminated them as a factor.  Now, however, a scientist points to another threat to the marsh:

Court Stevenson, a researcher at the University of Maryland Center for Environmental Science at the Horn Point Laboratory in Cambridge, adds a fourth effect: marshland damage caused by hungry geese. Snow geese are particularly harmful because they chew the marsh’s roots, he said.

He criticized the U.S. Fish and Wildlife Service for what he sees as the agency’s overemphasis on sheltering migratory Canada geese. Federal land managers plant hundreds of acres of crops to help improve the health of the 25,000-acre refuge’s winter visitors.

“Sometimes they try to manage by the species instead of the whole system,” Stevenson said.

As goose numbers rise, he said, a lot of the marsh plants are now getting eaten instead of being allowed to wilt and become peat, rebuilding the land.

Scientists estimate that the refuge has lost 5,000 acres of tidal marsh over the past century, though Stevenson believes the number is probably closer to 8,000. Baird said that snow geese “are of great concern.”