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Birdwatching at Corkscrew Swamp, in southwest Florida
Florida's beautiful Corkscrew Swamp plays an important role in the survival of the Wood Stork and holds in store many joys for visiting birdwatchers
Published: July 1, 1991 At Corkscrew Swamp in southwestern Florida, a weathered boardwalk will take you back in time, to a place where ancient rites of bird courtship, mating, and nesting have occurred for centuries. The boardwalk takes you into a lush, green, primeval forest where you will find the country's largest remaining stand of virgin bald cypress. Some of the trees are over 700 years old, towering to 130 feet. Almost instinctively, you will find yourself looking up, expecting to see pterodactyls flying in the air with their leathery wings outstretched.
Instead, if you visit in March or April, you may be fortunate enough to see a large, white bird with jet black wings and a grayish bald head soaring overhead — the Wood Stork, which has nested for centuries at Corkscrew, although its breeding success is rapidly declining in this land of anachronisms.
From February to August, you'll be certain to encounter Swallow-tailed Kites or Red-shouldered Hawks. Along portions of the nearly two-mile-long boardwalk, you'll be covered by a remote canopy of sounds which will echo in the deepening green. These are sounds that have been heard for centuries, too. Carolina Wrens, which live at the swamp year-round, repeat their "Tea-kettle, tea kettle, tea kettle, teas." Tufted Titmice sing their clear, continual whistles and Pileated Woodpeckers pierce the air with their jungle-like cries.
The best way to get acclimated to this mystical place is just to stand still and listen, enjoying the remoteness. Visitors are courteous and quiet here. Careful listeners cannot only pick out the loud "kleeyur" calls of the Red-shouldered Hawks, but also the quiet buzzes of Northern Parulas and the song of Black-and-white Warblers. Red-shouldered Hawks live year-round at Corkscrew, while Northern Parulas arrive from South American rain forests in early spring to remain until fall.
These are just a few of the 186 species of birds sighted at Corkscrew Swamp, an 11,000-acre, protected forest and marsh. A diligent birder may spot 40 to 50 species in one day along the boardwalk, especially during spring migration in March and April, according to Corkscrew's former naturalist Paul Hinchcliff.
As early as 1912, the recently formed National Audubon Society, which manages the sanctuary, recognized the need to preserve this area because of its importance to birds and other wildlife. Back then, the society employed a seasonal warden, with the permission of the swamp's owners, to protect Wood Storks and Great Egrets from destruction by plume hunters in Corkscrew's nearly impassable swampland.
But development soon ran rampant, and in 1954, 14 conservation organizations united to form the Corkscrew Cypress Rookery Association. John H. Baker, then president of the National Audubon Society, helped to collect monies needed to purchase land and to build a boardwalk on a portion of this remnant of the Big Cypress Swamp of Collier County.
Corkscrew Swamp is tailored to the needs of novice and advanced birders alike. If you have questions, naturalists and volunteer docents with spotting scopes are stationed at several strategic spots to point out nesting and mating activity.
Each year, generally during March and April, you usually can find a scope focused on the long, scissor-like tail of a Swallow-tailed Kite keeping its eggs warm. Scopes are often set up near the kites' nesting sites which are situated at the tops of the tall cypresses. Depending on when you visit, you can see nesting or feeding activity in this area.
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Swallow-tailed Kites, which winter in South America, habitually come to nest at Corkscrew at the end of February where they remain until late August. During those times you can usually see the agile and graceful bird soaring above the swamp — its long, V-shaped, black tail boldly apparent against the blueness of the sky — snatching dragonflies in the air as it has done for centuries. They will also feed on the snakes and lizards of the swampland.
While looking up to see the kites, I noticed long holes in the cypress trees — signs of Pileated Woodpeckers — elusive, red-crested creatures that are often heard but not seen at Corkscrew. At this writing, Pileateds are doing well, in part because of the increased foraging habitat which resulted when lightning storms downed a large number of pine trees.
Next, I came upon a pocket of warblers — Prairie, Yellow-throated, and Black-and-white, and Northern Parula — plus an active little Blue-grey Gnatcatcher — feeding, chattering, and hopping about undisturbed.
On my visit to Corkscrew, I was fortunate enough to see a female Ruby-throated Hummingbird sitting on her mud-packed nest on a tree branch. The swamp is near the southernmost breeding area for Ruby-throats.
Farther down the walk, I arrived at Lettuce Lake, where a Little Blue Heron was daintily searching for crayfish, small minnows, and insects, while a large alligator preferred to laze in the sun. Many large wading birds, such as the Great Blue and Tricolored herons, Black-crowned and Yellow-crowned night-herons, Snowy and Great egrets, and White Ibis can be found here as well. While enjoying the birds, I also looked for red-bellied turtles, a black racer winding through the aquatic grasses, strangler fig trees, and other forms of life that have been here far longer than our ancestors.
A naturalist dipped his net into the swamp to show me why it was unnecessary for me to bring insect repellent to Corkscrew: inch-long, insect-eating mosquito fish, which were keeping the peace here long before anyone ever heard of mosquito control. These mosquito fish are one small part of the delicate balance of Corkscrew's ecosystem, a balance that has existed for ages but now has a precarious future.
Over the years, more land has been purchased to preserve the swamp's integrity, which is continually threatened by nearby development. Maintaining a large swampland provides habitat for the Wood Stork, considered by Everglades National Park authorities to be one of the most endangered species in the United States.
It is speculated that in the mid1930s, some 15,000 pairs of Wood Storks nested in what is now Corkscrew Swamp. Three decades later, 6,000 pairs of Wood Storks bred at the Corkscrew rookery and 17,000 young were fledged. In 1988, less than 2,000 were fledged.
Hinchcliff explains how human forces, coupled with the unpredictable forces of nature, have plagued the Wood Stork. Seasonal dynamics play an important part in the life cycle of the Wood Stork, a particularly sensitive and narrow-niched species. The bird feeds by a touch/grope method, rather than by sight, probing the shallow waters for fish.
For successful breeding, Wood Storks need a wet season in which fish will breed and multiply, followed by a dry season so the fish will be concentrated in one area. Says Hinchcliff, "Once a parent stork makes a commitment to nesting, he or she prefers to feed within a 20-mile radius and will then spend four months rearing young." Unusually long dry seasons or unusually short wet seasons can disrupt the Wood Stork's nesting ability, causing fluctuations in the number of young fledged.
"The plot thickens as the water regime in this area is manipulated and fewer fish are available," says Hinchcliff. "Draining, diking, conversion of marshes to agriculture, and polluting of estuaries has reduced the numbers of available fish. This affects not only the Wood Storks but other wading birds that frequent Corkscrew, such as egrets and herons, along with alligators, raccoons, opossums, and on up the food chain to the Florida panthers and us."
When and if the Wood Storks will return to Corkscrew from their winter homes in South America becomes more of a mystery each year as areas that surround their nesting territory are altered. But the recent purchase by the South Florida Water Management District of 7,000 critical acres adjacent to the sanctuary is certainly good news for such species as the Wood Stork.
Subsequent visits to Corkscrew showed me how the forces of nature can cause fluctuation in the Wood Stork's reproduction rate. In 1988, I had the chance to see Wood Storks flying and later huddling quietly on their nests. I didn't realize how extremely fortunate I had been. I returned exactly a year later, but the Wood Storks didn't.
Hinchcliff explains, "The Wood Storks historically arrived at Corkscrew from early December to mid-February. But since the winter of 1988 was unusually wet in Florida, the storks didn't arrive until mid-March. We knew it would take them four months for their young to be fledged," he says.
But the rainy season usually starts in mid-May at Corkscrew, and officials feared more rain would further disperse the fish, making fishing more difficult for the storks. Hinchcliff envisioned half-grown chicks starving on their nests. "We needed a miracle," says Hinchcliff. And they got it. Corkscrew's unusually long wet winter in 1988 was followed by an extended dry season which kept the fish concentrated in smaller pools. Nineteen hundred young Wood Storks fledged at Corkscrew that year, a total not surpassed since 1980.
But the dry season (usually October through May) continued, and there wasn't enough of a rainy season to again increase the abundance of fish that would bring the storks back in 1989. It was a bittersweet day in March, when we looked for the Wood Storks and found none. At the end of April they still had not returned to Corkscrew.
Hinchcliff says there were small rookeries of Wood Storks reported in southern Georgia and to the north of Corkscrew in 1989 (see Manry, "Living on the Edge," Vol. 4, No. 5, 1015), but certainly not the sizes that had been seen at Corkscrew in the past. "Wood Storks are being displaced from their historic breeding center," Hinchcliff says.
As Corkscrew Swamp continued to experience a drought, the fate of the Wood Stork continued to be a burning question. But just as things seemed hopeless, the Wood Stork, which didn't nest there in 1989, came back in March of 1990 and set up housekeeping. The colony of 310 pairs of "flintheads" fledged 470 young last July. Says Corkscrew Swamp Manager Ed Carlson, "The efforts and dedication expended to raise those young were just amazing. Because conditions were so dry, the adults were forced to fly great distances for food. Toward the end of the nesting season, it was common to see only one or two adults in the entire colony of 300 nests. All the rest were out searching for food. The nestlings would sit patiently, waiting for hours at a time. They were subject to rain, wind, heat, and predators, but they made it."
The latest word on the Wood Storks at Corkscrew is a good one. By the end of March of this year, 300 nesting pairs had returned.
When should you visit Corkscrew Swamp? Any time of year. If you're lucky, you can time your arrival a day or two after a weather front moves through, as fronts will bring in a variety of wading birds to the area. If you want to search for songbirds and wading birds, come sometime after December. By April and May, you can observe southern migrants passing through on their way north. In summer, it's quiet, peaceful, hot, and often rainy until October. A flurry of migration activity begins again in the fall.
Come to Corkscrew for the Wood Storks. Hinchcliff worries that the next generation of birdwatchers may not have a chance to see this unusual species in the United States. "It's not just a matter of seeing a striking bird," He says. "You have to think that if the land here in southwestern Florida can't support this species, how much longer can it support us? If we can protect lands like Corkscrew, we can protect a piece of the past that could greatly affect our future."
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Author's Note: Corkscrew Swamp is open daily from 9 a.m. to 5 p.m.
An entrance fee is charged. Children under six are admitted free when
accompanied by an adult.
To get to Corkscrew, take I-75 north
from Naples or south from Fort Myers to Exit 17, which is County Road
846. Head west on 846 for 16 miles to signs directing you to the
visitor center.
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Sheryl DeVore, in addition to her freelance photography and writing, is the staff feature writer for Pioneer Press in Illinois. She volunteers her time as a docent and bird-walk leader at Ryerson Conservation Area.
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