We take a speed boat out to Bird Key Stono on a warm evening in late May. The air is sweet and humid and as we level out at speed, it fills our eyes and mouths and clothes. We only shout occasionally, briefly, our voices lost to the wind. From the west, Bird Key doesn’t look like much: a flat disc of shimmering sand on the crisp blue of the horizon.
Officially protected since 2006, Bird Key Stono Seabird Sanctuary sits in the wide estuary of the Stono River, between the easternmost point of Kiawah Island and the south end of Folly Beach. As a small barrier island, it is dynamic, constantly shifting in shape and size. A mixture of salt marsh, vegetated dunes, beach, and intertidal shoal, the roughly thirty-five acre preserve is one of five seabird sanctuaries in the state.
As we draw near, the shoreline comes into view and the breath catches in my throat. The boat slows and we idle at the buoys, not saying anything. Pelicans, too many to count, line the beach. They stamp their flat, waxy feet and cool their bodies with abbreviated flaps of massive wings. They are magnificent, relics from a prehistoric past, and in such numbers, their presence feels weirdly divine.
South Carolina supports around ten thousand brown pelicans, 40 percent of the Atlantic population. According to Janet Thibault, South Carolina Department of Natural Resources (SCDNR) wildlife biologist, Bird Key is currently the biggest rookery in the state and crucial to that population.Though the statistics, she tells me, are constantly in flux. This year the pelican count was down to 2,770 from a staggering 3,313 last year. The previous year they counted 3,790. Thibault attributes this to a couple of factors. The fluctuating numbers have a lot to do with other seabird islands. If other sanctuaries are threatened, Bird Key sees an uptick. Pelicans need an island with no mammalian predators or human disturbance, with enough material to build their nests. These isolated barrier islands are ideal, with dunes for nesting and a wide intertidal zone to cool off and to learn to fly.
The official sanctuary status, she notes, also has a lot to do with population numbers. It is strictly prohibited to land on the island from March 15 to October 15, and even in the winter months, the dunes are still off limits. But it took a couple years for boaters to realize they couldn’t land on Bird Key. That, Thibault reports, makes all the difference. Human contact dramatically affects seabird habitat, and if the birds don’t feel safe, they move on.
As far as predation goes, it’s too far for most mammals to swim from the mainland. However, in the last year, Thibault tells me, they’ve noticed mink tracks out on the island. Mink are incredible swimmers and prime predators for beach nesting species. If a predator does make it to the island, it can make quick work of a seabird colony.
It’s hard to imagine a beach more alive with birds. As we idle north against the leeward shore, the birdlife becomes more diverse. A few pelicans still stand at attention, but numerous other species punctuate the landscape. Willets skitter through the lapping tide and royal terns hunch solidly in groups, their punky, tufted heads ruffling in the breeze. The island is home not only to seabirds like pelicans and terns but also to shorebirds like oystercatchers and willets. Waders, a category that includes ibis and egrets, come to and from the island throughout the year as well, though they don’t require such a specific nesting profile.
The north end of the island is a rise of white sand connected by a skinny sandbar. This sand was deposited as part of a renourishment project a few years ago. We idle around the corner, and the wind hits us at full force. From this side we can see the topography a bit better. Crested dunes slope up from the striated intertidal zone. In the higher areas the dunes are dense with scrub and grasses. A bit further south along the shore, the water has cut a steep cliff of sand, and it rises six vertical feet. It feels a bit like a desert island, a romantic undiscovered isle governed by the tides.
But that is to say nothing of the birds. There are infinitely more pelicans on this side of the island. The beach, the water, the air is alive, teeming with ibis, egrets, oystercatchers, and willets. As we idle south along the shore, the birds seem to surround us, a dense crush of wings and feathers. In their sheer size, the pelicans dominate the scene, but terns and gulls skim and swoop in the air. Hordes of birds crowd the beach, preening and flapping. And the sound! It is a literal cacophony, layer upon layer of squawking and shrieking. Groups of five or six pelicans fly to and from the island together, gliding uniformly in a line. The way they land and take off together reminds me of an airport. There is an air of business to their comings and goings. Occasionally we see a pelican nosedive, dropping dramatically into the ocean without so much as a splash and then bobbing to the surface a few moments later.
Bradley Wilkinson is a PhD student at Clemson University and an affiliate of the South Carolina Cooperative Fish and Wildlife Research Unit. He spends nearly every day during the breeding season on Bird Key, studying the migration, diet, behavior, and environment of the brown pelican. He explains later that these pelicans are “plunge diving” for Atlantic menhaden, a schooling fish that makes up the majority of their diet. Their heads, neck, and chest are padded for this tremendous impact and instant density change of the dive. And though the pelican’s wings, beak, and feet are quite substantial, Wilkinson says the bird is surprisingly light. Their bodies are filled with small air sacs to counteract the weight of these extremities and to buoy them from their deep dunk into the ocean.
The oxeye and seagrass on the upper dunes of the island are alive with movement. I can just make out the pale yellow heads of the nesting pelicans. Unlike other seabirds, pelicans actually build a nest from branches and grass (by contrast, terns scratch a shallow depression in the sand). In early March they gather to court and mate. By April the couples are building nests, and the colony is in full swing. They lay three eggs each season, and both males and females incubate the eggs (with their webbed feet!) for about a month. Eggs begin to hatch in late May. The chicks are altricial, meaning they don’t leave the nest and they depend on care and food from their parents during the first three or four weeks of life.
After this phase, the pelican hatchlings develop downy feathers and start to wander from the nest. And the following month, they become independent from their parents and grow their flight feathers. That’s when the beaches of Bird Key are really alive with birds, says Thibault. The population appears to explode in the later months of summer, when the juveniles inundate the beach.
Many of these pelicans migrate south in the fall. The pelicans we see in the Lowcountry in winter are often birds from North Carolina or Virginia, says Wilkinson. However, he explains, that pelican migration is facultative. Some pelicans stay year round, and some fly as far south as Cuba or Belize. Wilkinson and his colleagues aren’t entirely sure why, though previous work by his research lab has shown a strong correlation between the size of a bird’s nesting colony and whether or not that bird migrates. The larger the colony, the more likely the bird is to head south in winter. Also pelicans are extremely sensitive to cold weather. The Lowcountry hit record lows two winters ago, and Wilkinson tells me that not a single bird from the cohort they study with specialized GPS transmitters stayed in the state. And though their migration is likely based on resources, habitat, and weather, I like the idea that it’s preferencial, that they head south when they feel like it (anthropomorphic, admittedly). Imagine these very pelicans gliding through the sky somewhere warm in six months, enjoying the tropical climes of Mexico or the Carribean like a bird on vacation.
We don’t speak much on our windy ride back up the Kiawah River. A wall of thunderclouds builds in the west, and the air becomes even more dense with the impending storm. The sun breaks through here and there in luminous, crepuscular rays. We slow and idle towards the dock at Rhett’s Bluff, where a few small groups have gathered to watch the dramatic display of clouds and light. — H.W.