The natural side

Author: By Carol K. Dumas, Globe Correspondent

Date: SUNDAY, November 16, 1997

Page: M1

Section: Travel

Then, if you have a chance, drive south toward Naples and rediscover the old Florida, before man's intrusion, before the swamps were drained for amusement parks, where real animals and birds live undisturbed. Walk along a boardwalk and listen to the sounds of birds you've never heard before, the whisper of reeds growing thickly together, the crackle of an unseen animal moving in a thicket -- the sounds of nature, preserved.

Southwest Florida's Corkscrew Swamp Sanctuary is off the beaten path -- that is Interstate 75 south, some 15 miles off Exit 17 -- and thank goodness for that. Otherwise, this 11,000-acre wilderness where the oldest remaining stand of virgin bald cypress in North America is found, would be paved over just like much of Florida appears to be. Ever see old black and white footage of the pre-Disney World area? Corkscrew Swamp looks like that today and is sure to remain that way, thanks to its caretakers, the National Audubon Society.

The effort to preserve the area grew out of an initial concern to protect wood storks and great egrets in 1912. It wasn't until 1954, however, that the Corkscrew Cypress Rookery Association was formed through the merger of 14 conservation groups and many individuals. Owners of the standing timber, which was once the Big Cypress Swamp, agreed to cooperate in the conservation effort, even contributing acreage of bald cypress and cut-over lands for buffer zones.

Audubon accepted responsibility for managing the area and called it Corkscrew Swamp, after the name given by the first settlers to the winding river that snakes throughout the swamp area.

For a small fee ($6.50 for non-Audubon Society members), compared with most of Florida's man-made attractions, visitors take a self-guided tour along a 5,800-foot-long boardwalk that weaves through swampland and forests, along ponds and wet prairies, with guaranteed sightings of many common and rare birds, mammals, and reptiles, including alligators.

The trail has stopping points that correspond with numbers in the trail guide lent to each visitor. There are benches for resting or pausing to observe nature's creatures in the wild. Visitors can also buy for a quarter a checklist to mark any bird sightings, a good activity to occupy the children, who may be so Disney-ized they may think nature is just plain unexciting in comparison.

Corkscrew Swamp is a bird-watcher's paradise. Depending on the season, visitors can see 12 kinds of heron (we saw little blue herons, great egrets, and many, many white ibis in February), 11 kinds of ducks, black and turkey vultures, kites, hawks, eagles, osprey, and three kinds of falcons. Wild turkey are common and there are seven kinds of woodpeckers (we saw a beautiful pileated woodpecker busily hammering away at a dead cypress tree), four kinds of owls, numerous warblers, thrushes, finches, and other common birds -- probably a large number of the birds listed for the eastern United States in any bird book. The rare wood stork, which has a wing span of 66 inches, was seen nesting in the cypress trees along the Lettuce Lakes during our visit. Vultures circle overhead and the red-shouldered hawk is a common sight along the boardwalk.

But many visitors hope to see Corkscrew Swamp's bigger attractions, and they are usually rewarded with several sightings of alligators who like to sun themselves, lying completely still, just a couple of feet from the boardwalk. We easily saw a dozen, not counting a mother and her numerous babies lounging on a fallen log that projected out into the water. Some of the adults are more than 10 feet long.

Besides alligators, there have been bear and bobcats seen from the boardwalk, and an occasional otter. Bright green Carolina anoles or blue-tailed skinks are two of the most common lizards seen running along the boardwalk. Keen observers can also detect turtles (there are eight species living in the Corkscrew Swamp, the red-bellied is the most common) or snakes, like the eastern cottonmouth, slithering along, partially submerged in the water.

The most active place to view alligators, turtles, and birds are the Lettuce Lakes, most of which are covered by pistia straitotes, or water lettuce. The water level in the Lettuce Lakes can be as deep as 4 feet to just a few inches in the dry season. When the water is low, it becomes a lifeline for the reptiles, birds, fish, and mammals who are drawn to it feed on other forms and on each other. Many other areas of the swamp are covered with the dainty green duckweed, one of the smallest of all flowering plants.

There seem to be two varieties of cypress within Corkscrew Swamp, but the smaller variety, seen at the beginning of the boardwalk, is actually a site adaptation. According to Audubon, the pond cypress, which has different foliage and is smaller than the bald cypress, evolved because it sits on higher levels of bedrock. The trees often have bromeliads, a type of air plant, attached to their branches and trunks.

Farther into the swamp lie the famed baldcypress, which boardwalkers will immediately recognize for their larger girth. The name comes from its shedding of leaves in the winter, leaving the trees bald; cypress are the only conifers that shed their needles in winter. Mostly all of the large stands of bald cypress have been cut for timber; the Corkscrew Swamp holds the largest left in its natural state in North America.

One of the strangest site adaptations are the so-called cypress knees. Growing up from the roots of the cypress trees, these peculiar, 3-foot-high kneeslook like stumps, except they are rounded off at the top, and their actual purpose has long been debated by naturalists. Some say they act like breathers for the tree, but others feel the knees may provide structural support for the cypress where it grows in unstable sites. The knees do not produce foliage or grow into trees.

While plant life and trees are easy to spot and identify, visitors should bring binoculars along for the best views of birds and other wildlife that are hard to see in the swamp and forest camouflage. The sanctuary gift shop rents good quality binoculars for just $3 if you've forgotten your own. Don't forget your walking shoes.

While the trail may be long, especially in the hot afternoon sun in southwest Florida, visitors don't have to worry about one pesky creature: Mosquitoes are virtually absent because of the tiny fish called gambusia or mosquito fish, which are so numerous in the swamp water. Their main diet is mosquito larvae. It's another example of the way nature's food chain works remarkably well when left undisturbed by man.

The sanctuary is open from 7 a.m. to 5 p.m. December through April and from 8 a.m. to 5 p.m. May through November. Admission is $6.50 for adults ($5 for Audubon members), $5 for college students, and $3 for children in kindergarten through grade 12. Children under 6 are free.