Jan/Feb 2021Bird Key Stono by SCDNR wildlife biologist Janey Thibault
A partnership built on more than sand.
From time immemorial, people have been drawn to the ocean. It’s the same here in South Carolina, where our vast shoreline needs protection from erosion, storm surge and hurricane damage. When you think of beach renourishment, you think of preserving the integrity of the communities that live just beyond the dune line — the businesses, restaurants and attractions that bring tourists to the shore. Protecting those economies and those properties from storm surge has been a fact of life in coastal areas that seem to wash away a little each year.
Beach renourishment, the act of pumping sand back onto beaches, is the way many coastal communities are able to continue to exist. Not only do coastal communities benefit from the moving and shaping of the sand, a myriad of wildlife species also reap a reward from the work.
The life of an ephemeral sandbar is fleeting. Because of tidal overwash and seasonal storms, sand is deposited and washed away in a dynamic dance between winter and summer. The South Carolina Department of Natural Resources (SCDNR) owns and manages several of these estuarine islands that change in size and are extremely valuable to the wildlife that depend on them. With the frequency of fall hurricanes and the few natural refuges left for coastal wildlife, these places need a nudge every once in a while. In comes the United States Army Corps of Engineers (USACE), whose mission is to "Deliver vital public and military engineering services; partnering in peace and war to strengthen our nation’s security, energize the economy and reduce risks from disasters," and part of this mission involves the maintenance of navigable waterways.
The USACE Charleston District was established in 1821, and in the early days they were involved with the construction of Charleston Harbor’s forts and jetties. Today, the District maintains approximately three hundred miles of navigational channels along the coast of South Carolina from Little River to Port Royal Sound. With state-of-the-art survey equipment and the experience of professional engineers and planners, the Charleston District oversees dredging projects that maintain federal navigation channels and make improvements like those occurring with the deepening of the Charleston Harbor to provide economic growth and prosperity for the state. In conducting these projects, the Charleston District must consider beneficial use options for that material. Most people are familiar with the term beach renourishment, where the USACE is involved in harvesting sand to place on beaches to reduce the risk of people and property to storm surge and mitigate continual beach erosion in areas like Folly and Myrtle Beach. However, many people are unaware of how the USACE uses beneficial sediments from dredging projects to maintain a federal navigation channel to benefit wildlife.
Bird Key Stono rests at the mouth of the Stono River, nestled between the southwest tip of Folly Beach and the eastern end of Kiawah Island. This thirty-five-acre sand spit was designated a Seabird Sanctuary by the SCDNR in 2006. The island offers ideal nesting and foraging conditions for seabirds and shorebirds. Colonial nesting species such as brown pelicans, and sandwich and royal terns lay eggs and raise chicks on this isolated island free of mammalian predators and devoid of human disturbance. Bird Key is also home to nesting wading birds such as egrets, herons and ibis. Over the last few years, this important Seabird Sanctuary has been eroding on its southwestern edge. Seabird and shorebird populations have declined 70 percent since the 1950s. Because South Carolina is home to a variety of important nesting and migratory coastal bird species, any loss of Bird Key or other seabird sanctuaries means less habitat available to the birds that need it the most. Conveniently for Bird Key and all the birds that utilize it, the USACE, when dredging the Folly River Federal Navigation Channel, had an opportunity to partner with the SCDNR to enhance and stabilize the island.
The most recent renourishment took place in early March of 2018 when the USACE began the process of pumping sand from the Folly River Federal Navigation Channel onto Bird Key Stono Seabird Sanctuary. The process took just over a week and 40,000 cubic yards (the equivalent of 4,000 dump trucks worth) of sand was deposited onto the island for a total project cost of $300,000, which was completely federally funded. The USACE would contribute sediment to Bird Key on an approximately three-year rotation when maintaining the Folly River channel, but due to lack of funds, it had been over ten years since they had been able to pump material onto the island. Over the last several years, storms and high tides have eroded part of the island, limiting space for nesting.
"This project was exciting to be a part of to be able to maintain the channel and provide an environmental benefit in stabilizing the island and enlarging important coastal bird habitat," said USACE Environmental Engineer Alan Shirey. The USACE team of engineers targeted an elevation of 9 feet with an area of 25,000 yards at the southwestern tip and another 15,000 yards along the Folly facing stretch of beach. The process is quite remarkable; a large cylinder carries a mixture of 30 percent sand and 70 percent water slurry that spews onto the island through a thick black pipe. Water uplifts from the pipe to break up the velocity causing the sand to build up. After the sand drops out, the water flows back to the inlet. Once a pile of sand builds up, bulldozers push the piles and grade it to a desired topography. USACE works with the United States Fish and Wildlife Service (USFWS) and SCDNR biologists to place the material to provide optimal bird habitat. In this win-win relationship, the birds benefit from habitat enhancement, and commercial and recreational boaters enjoy an open waterway from the Folly and Stono Rivers to offshore fishing grounds.
Because seabird colonies are sensitive to human disturbance, Bird Key Stono is closed to human activity during the nesting season from March 15th to October 15th while these birds court, build nests, lay eggs and raise their chicks. SCDNR staff put up closure signs and maintain them throughout the season. Wooden posts are placed at the high tide line and dug in with a handheld auger. Signs identifying the island as a seabird sanctuary are drilled into each post, designating the dates of the closure. Extreme tides and storms frequently knock down posts, so maintaining the closure signs Bird Key Stono Renourishment Project by Sara Corbett, U.S. Army Corps of Engineers, Charleston District, Public Affairs is a continuous effort of SCDNR staff.
The early days of the sanctuary designation were not always easy. Having an isolated island just off Folly Beach that was historically open to boaters and visitors, but now closed during the summer, took a little time for people to accept. Because of the potential conflict between recreationists and nesting seabirds, and the constant need for sign maintenance, a seabird warden was hired to act as an emissary between the public and the SCDNR Coastal Bird Program. The position was paid for through grants obtained by Audubon South Carolina, USFWS and the SCDNR to promote protection of South Carolina’s coastal resources. For several seasons, the seabird warden’s duties were to patrol all SCDNR sanctuary islands, especially on weekends, to educate the public about the importance of seabird nesting sites and the potential impacts of humans on those sites. After a few seasons, the birds returned to Bird Key Stono and residents of Folly Beach were excited to see flocks of pelicans soaring overhead, coming and going from the island to feed and rest.
To better understand the habitat needs of the species, and to understand the health and productivity of the birds nesting at Bird Key Stono, several research and long-term monitoring projects related to management have been undertaken. With the new protections of the seabird sanctuary designation, the SCDNR attempted to attract terns and black skimmers back to the island using social attraction techniques in 2007. Plastic decoys of royal terns, least terns and black skimmers were ordered, and Horry County school children painted the models under the supervision of Huntington Beach State Park staff. The decoys were placed on Bird Key Stono to resemble a nesting site and calls of terns and skimmers were broadcast from a sound system on the island. Immediately, the seabirds found the island and settled in among the plastic neighbors. The project was successful in drawing these birds to the island; although, avian predation kept them from being successful in nesting for a few years.
Annually, the SCDNR conducts counts of seabird colonies, and data have been collected at some sites since the 1960s. These long-term datasets help biologists detect population trends and distribution of nesting across the state. In the old days, pelican colonies were surveyed on the ground, walking among the nests and tallying numbers. Since 2012, nests are counted from aerial photos taken from a plane at the peak of nesting. Flying with SCDNR Law Enforcement Division pilots, biologists can census all of the seabird colonies in one day. South Carolina supports 38 percent of all brown pelicans nesting on the Atlantic coast. In the 1980s and 1990s, Bird Key Stono was the largest pelican nesting colony in the Southeast, but the final year that pelicans nested on the island was in 2004. After a ten-year hiatus, pelicans recolonized the island in 2014 with more than two hundred nesting pairs. The following year, the nesting numbers increased more than six-fold with 1,299 pairs of pelicans nesting on the island. Bird Key Stono is currently the largest pelican rookery in South Carolina, with more than 3,000 nesting pairs.
Most recently, Bradley Wilkinson, a PhD candidate with the South Carolina Cooperative Research Unit at Clemson University, has been deploying GPS transmitters on adult pelicans nesting at several colonies in the Charleston area to track their movements. By gathering information on pelican whereabouts in near real-time, they have been able to document where and how often pelicans use certain important pieces of habitat during the nesting season and to determine when adults leave the colony and migrate to winter resting grounds. Wilkinson is also recording reproductive success and aspects of the diet adults feed to their growing pelican chicks.
Migratory and Wintering Shorebirds
Not only does Bird Key Stono provide habitat for beach nesting birds, it also serves as a roost site and stopover location for migratory shorebirds. Hundreds of dunlin, semipalmated plovers and western sandpipers rest huddled along the sand mounds that serve as a wind break at high tide. As the water drops with the tide, these shorebirds spread out along the intertidal zone and forage on invertebrates such as polychaete worms and small crustaceans hiding within the mud flats and wet shoreline. The SCDNR conducts monthly surveys of shorebirds at Bird Key Stono for the International Shorebird Database, which helps in conservation planning.
The federally threatened piping plover, a small shorebird species, also utilizes Bird Key Stono as an over-wintering site. Tapping their orange legs upon the wet sand, these plump, greyish birds seek out polychaete worms in the substrate and once upon them, they pull them from the soil like a spaghetti noodle. Research on piping plovers has been conducted throughout their range, with scientists color banding birds in order to determine survival. The SCDNR conducts band re-sightings of plovers and, from that data, SCDNR biologists know that piping plovers from the endangered Great Lakes population spend the "wintering" months of September to March at Bird Key Stono. Because of this, Bird Key Stono has been designated as Critical Habitat for piping plovers by the USFWS under the Endangered Species Act.
A few months after the renourishment was completed at Bird Key Stono, seabird nesting was in full swing. Dunes lined with sea oats, beach morning glory, and sea oxeye were ringing three sides of the island, and shrubs and old snags were dotting its interior. Brown pelicans had built stick nests within the bowl of the island and terns were scraping out depressions to lay eggs atop the sandy dune ridges. Egrets, herons and ibis perched precariously in nests of twigs among gnarled tamarisk trees. With the help of the USACE, the island has been revitalized several times for South Carolina's coastal birds. The partnership between the SCDNR and the USACE is solid, built upon more than just sand.
If you are interested in learning how you can help coastal birds in South Carolina, SCDNR on-going research and information about the birds that inhabit the state, visit www.sccoastalbirds.com.
Bird Key Stono Renourishment Project
by Sara Corbett, U.S. Army Corps of Engineers, Charleston District, Public Affairs
In between Folly Beach and Kiawah Island lies an isolated island where thousands of birds flock and humans are not allowed.
While this might sound like the beginnings of a scary movie, it’s actually Bird Key Stono Heritage Preserve, a 35-acre bird sanctuary that the U.S. Army Corps of Engineers, Charleston District recently renourished.
"There were thousands of birds flying all around us," said Environmental Engineer Alan Shirey. "It was like a scene from 'The Birds,' except they weren't attacking us, they were more interested in their lunch that was being pumped out."
Historically, the District has placed fill on Bird Key Stono when dredging the Folly River Federal Navigation Channel, since it's the least cost disposal site for the operations and maintenance dredging of Folly River.
"This project is a win-win," said Shirey. "We are able to be good stewards of the taxpayers' money since pumping the dredged material onto Bird Key is the cheapest way to dispose of the material and protects the environment by increasing the footprint of Bird Key."
There are several government agencies that work together to protect the bird sanctuary. Bird Key Stono is listed as a U.S. Fish and Wildlife Critical Habitat for Piping Plover and protected under the Endangered Species Act, but it is owned by the State of South Carolina and maintained by the South Carolina Department of Natural Resources. So the Corps coordinated closely with USFW and the SCDNR to ensure that sand was placed in the best locations for the upcoming bird nesting season.
Renourishment on Bird Key Stono was important, as the island suffered significant erosion from Hurricane Irma, which left little room for birds to live and nest on. Forty-thousand yards of material was needed to replace the lost sand, approximately 4,000 dump trucks, which cost $300,000 and was 100 percent federally funded by the Corps. The cutterhead dredge Cherokee was used to suck up sand and water from the floor of the Folly River which was then pumped onto Bird Key Stono through pipes. Finally, bulldozers shaped the sand.
"It's a rare opportunity for us to renourish Bird Key Stono," said Shirey. "But I know…that the project will make a long-lasting impact to the birds and wildlife that reside on Bird Key Stono."
The Corps planned the dredging project around the spring nesting season so that the birds would have a new habitat before the season started.