Exploring nature's teeming nursery grounds

An ``adventure tourist,'' seeking physical challenges in exotic climes, wouldn't be attracted to the South Slough. Neither would a hard-core bird watcher, the sort obsessed with ticking off sightings on a ``life list.'' This quiet backwater has little to offer travelers to whom ``nature'' means a spectacular waterfall or towering mountain range. The South Slough Estuarine Sanctuary, the first such coastal refuge in the United States, instead rewards the visitor with the chance to observe a teeming ecosystem going about its everyday business. From the family stopping at the exhibit center and strolling on a self-guided nature walk, to the canoeist relishing the solitude of the bay's upper reaches, South Slough invites exploration of one of nature's most richly productive yet least-studied habitats: an estuary.

Estuaries are places where rivers meet the sea and the tides mix fresh water with salt. They serve as nursery grounds for a wide variety of fish and shellfish and as crucial resting and feeding places for migratory birds. But they have been disappearing at a dizzying rate. Sheltered bays at river mouths are inevitably magnets for civilization, and an estimated 40 percent of all estuarine tidelands in the continental United States have vanished since the first settlers at Jamestown made themselves at hom e on a branch of Chesapeake Bay, the nation's largest estuary.

Congress established the national Estuarine Sanctuary Program in 1972 with three basic purposes: to protect a number of key habitat areas, to permit continuing scientific research, and to educate the public in the nature of estuaries through school programs and facilities for drop-in tourists. There are now 17 sanctuaries (with an ultimate goal of 20 or more), ranging from Apalachicola Bay in Florida, which encompasses a diverse region of 180,000 acres, to such urban estuaries as the Hudson River near N ew York and the Tijuana River on the US-Mexican border.

South Slough, an arm of Coos Bay on the southern Oregon coast, was set aside in 1974, thanks to a grass-roots local effort to protect the area, which was already under way when the national legislation passed. The area comprises 4,400 acres of channels, mud flats, marshes, and forested uplands at the upper end of the long, narrow slough, which is fed by a number of small creeks. The lower end, toward the ocean, remains in private hands but is little developed. South Slough meets Coos Bay at Charleston, a pleasant if economically depressed fishing village.

Like most estuaries on the West Coast, South Slough is a drowned river mouth, filled by the ocean when sea level rose after the last ice age. At high tide the water laps virtually to the roots of the dark spruce and fir that ring the water. At low tide, a canoeist or kayaker has to keep a sharp eye out to find a navigable channel. Most of the bay becomes a vast mud flat, abounding in invertebrates from clams to infinitesimal worms and copepods, fed upon in turn by a diverse assemblage of birds.

A visit to South Slough will likely begin at the recently opened interpretive center, high on a bluff some five miles inland from Charleston, with a view down the estuary to the ocean breakers beyond. Directions can be obtained here to the several posted trails that wind around the creeks, channels, and coves of the estuary, providing a reasonably thorough natural history lesson along with some excellent vantages for casual birding.

Those inclined to penetrate more deeply will probably want to equip themselves with a canoe or rowboat. It's also possible to hike around to the seldom-traveled east arm of the slough on old overgrown logging roads. The hiker, however, is advised to be prepared for bushwhacking through heavy stands of salmonberry.

Most visitors will no doubt look first for wildlife, and with patience there are many species to be seen. Mink, racoon, and bobcat are found here, although they are unlikely to put in an appearance for any but the stealthiest observers. Deer and elk are a more common sight. Beaver are prominent residents; although the animals are hard to catch in the open, signs of their work are everywhere along the creeks within the sanctuary. In the bay itself, harbor seals and California sea lions are frequent visit ors, especially near the mouth.

Estuaries are usually stopover or wintering places for migratory shorebirds and waterfowl, and many of the sanctuaries are favorite haunts for bird watchers. (Two of the others, Padilla Bay north of Seattle and Elkhorn Slough on California's Monterey Bay, are among the best places for birding on the Pacific Coast.) South Slough isn't famous for sheer numbers; birders visiting the area will also want to go stalking in Pony Slough, another arm of Coos Bay a few miles north, where much larger concentration s can be found. But South Slough is a superb locale for observing birds occupying their natural habitat undisturbed.

``In general, it's a good place to go birding, in terms of watching bird activity,'' says Dan Varoujean, a biologist from the nearby Oregon Institute of Marine Biology who is studying the slough's bird populations. ``I'm not a big bird-list man, myself. I like to go out and watch them behave naturally.''

Among South Slough's residents and frequent passers-through of note are bald eagles, white-tailed kites, peregrine falcons, and osprey. A wide variety of shore birds has been spotted there too, including heron, dunlin, sanderling, black-bellied and semipalmated plover, whimbrels, Western and least sandpipers, . . . and the list goes on. Practical information:

To reach South Slough Estuarine Sanctuary, take the Cape Arago Highway south from the city of Coos Bay; turn on Seven Devils Road out of Charleston. For more information, contact the sanctuary office at PO Box 5417, Charleston, Ore. 97420; (503) 888-9015.