SAVANNAH, Ga. – To some people, a dredge disposal area might not seem very exciting—but to thousands of shorebirds it’s a safe haven, providing beneficial habitat and protected nesting sites.
The U.S. Army Corps of Engineers Savannah District completed construction of a new 8-acre bird island in March, located at the Savannah Harbor Dredged Material Containment Area (DMCA) 12A. It's one of seven areas that stores sediment dredged from the Savannah River federal shipping channel.
“This year is the first nesting season since we completed the island, so we are excited to see how birds will use it," said Ellie Covington, a biologist with the Corps' Savannah District.
Covington said the island provides valuable bare ground nesting habitat for many species of colonial water birds such as the least tern, gull-billed tern, black-necked stilt, black skimmer, and other shorebirds.
During nesting season (April through August), Covington and her team visit the Savannah Harbor DMCAs once a week.
“We make sure the ongoing sediment disposal operations are not interfering with nesting of migratory birds," said Mary Richards, a Corps biologist who accompanies Covington on her bird-spotting missions. "As part of that work, we count birds and nests to estimate how many birds and how many different species are using these areas. We also look for signs of predators and take corrective actions to reduce predation.”
So far Richards and Covington have counted more than 300 nests at the new island. Nests include black skimmer, black-necked stilt, gull-billed tern, and least tern—the latter of which is listed as a threatened species in South Carolina.
"We typically do our counts from inside a vehicle using a spotting scope, so we are less likely to scare up the birds," Covington said. "Each day is different, but it's not unusual to spot several species in flocks of more than 1,000 birds."
"It's hot, buggy, exhausting…and amazing," she added.
The bird island was part of a $5.3 million dike raising and improvement contract, awarded to prime contractor Edgefield Construction based in Edgefield, South Carolina. Construction began in September 2012 and finished in October 2013. Impoundment of the bird island began soon after, as water was pumped into the disposal area to surround the island.
"Because the island is surrounded by water, it is less likely that predators such as feral hogs, coyotes and raccoons will be able to access it," Covington said.
The 12A project used 877,000 cubic yards of previously deposited dredged sediment from inside the DMCA to raise the dike and another 160,000 cubic yards to create the bird island.
The island was topped with an additional 36,000 cubic yards of coarse sand re-located from nearby disposal area 14B. The sand forms a two-foot layer that provides better nesting habitat for shorebirds and slows the growth of plants that interfere with the shorebird nesting.
The Corps built the bird island as environmental mitigation for routine operations and maintenance of the Savannah Harbor Navigation Project. To document the project’s compliance with the mitigation requirements, the Corps produces an annual report on bird populations and habitat in these areas.
"So much historic bare ground nesting habitat has been lost worldwide due to human development that many bird species have become extinct or endangered," Covington said. "By providing this rare habitat, the Corps is helping to restore hope for several species' recovery."
In total, the Corps' Savannah District operates five interior bird islands with two more in the design phase, and two near-shore islands. Wetted areas within the DMCAs provide thousands of acres of feeding habitat for waterfowl and shorebirds; and the exterior woods around the Savannah Harbor DMCAs provide hundreds of acres of feeding, roosting, and nesting habitat for other bird species.
"We routinely coordinate with the Georgia and South Carolina Departments of Natural Resources, the Georgia Department of Transportation, and the U.S. Fish and Wildlife Service to ensure these areas meet state and federal requirements," Richards said. "It's definitely a collaborative effort."