The breeze blowing off Lake Erie seems premature, far too soon and too cool for dusk on an early September evening. Yet before Erie's inland feels the chill, autumn comes to Presque Isle State Park, the "almost island" that jets out like a hook into the waters of the Great Lake. The vivid colors of the beach's summer sky have already muted: The setting sun today is draped by a layer of clouds, the dark blue water, as if shaded by a child's crayon, blending smoothly into a gray horizon.

The shorebirds feel it too, heading south or to the Atlantic shore as soon as the September winds cross the lake. Ironic that these birds, which thrive best in unpopulated places, must leave the park just as the tourist season ends.

Nearly 30 years ago, shorebirds nested along the distal tip of the peninsula, a secluded section of beach too far from the road for people to use. But in the '50s and '60s, boaters began to anchor there and swim ashore. As a result, the tiny, earth-toned shorebirds -- sanderlings, sandpipers, piping plovers, ruddy turnstones, dunlins, redknots, whimbrels -- simply stopped nesting there. In 1993, to see if the birds would come back, the park closed the end of the peninsula to boaters (and to everyone else).

Though they have started to use the area for resting and feeding, only common terns have yet nested, raising the question: Did the park close the right stretch of beach? According to Penn State-Behrend biology major Lisa Borgia, the perimeters of the managed areas were based on subjective research -- on where the birds had nested before, not on why the birds had chosen those areas.

"There's never been any scientific research that I know of to show that this is the area birds prefer, that these are the characteristics of the habitat that they prefer," she explains, sitting on a piece of driftwood facing the calm water of Lake Erie. A brownish-gray sanderling, apparently a late migrator, pecks at the sand nar the shoreline; it is smaller and more jittery than the gulls flying nearby. "What kinds of organisms do you find out there? Do the birds like open areas or vegetated areas? Do they like beach or grass? How can you say what areas you want to protect if you don't know which areas the birds really use?"

Supported by a fellowship from the National Science Foundation and a permit from Harrisburg to use the managed areas, Borgia is studying the shorebird population on Presque Isle to answer these questions.

On each of five different areas of beach, which include shorelines, ponds, and grasslands, she randomly laid three 10-by-2-meter nylon rope grids. She moved to a spotting scope set up far enough away not to disturb the birds but close enough to see them in the grids. Every 10 minutes for 70 minutes, she counted the birds in the grids.

"You have to do it with a strict method, otherwise it becomes just birdwatching," she explains. The single mother of a 10-year-old son, Borgia says it was her intense interest in ecology research that inspired her to stop trying to balance a daytime job with night school and to enroll in college full-time. "The bird has to be there at 7 a.m. or 7:10 or 7:20. If he moves off the grid or comes back onto the grid in between, I can't count him."

Then she collected samples of the sand in the grids, jamming a glass into the sand, "taking the muck," and later examining it under a microscope to see which organisms the birds might be eating: midges, insect larvae, tiny crustaceans, or zooplankton.

"I now know where certain birds like to be. I know when they like to be there. I don't know what they eat when they're there, but I know what's in the soil they may be eating out of," Borgia says, after two morning and two evening observations in each of the five areas (one public and four in the managed area), the whole process conducted during spring migration 1995 and repeated during the fall.

"Now not only can I say, 'Yes, the managed areas are working,' I can also say, 'Dunlins prefer more vegetated inland ponds and no human interference. Spotted sandpipers don't care who's walking down the beach, and they like big waves and no vegetation.' So if you want to attract more front-beach birds, for example, you need to protect more of the shoreline."

But the shoreline is a highly dynamic environment: The lake's waters constantly dump sand at the tip. Since 1986, says Borgia, three or four large ponds have formed, and acres of sand have been deposited. As the peninsula grows, so does the controversy in Erie over who has the right to use the beach -- birds or boaters?

"We need to know what the birds like and where they like it, so that as the peninsula changes," explains Borgia, "the managed areas can change with it."

Lisa Borgia is an undergraduate student in biology at Penn State Erie, The Behrend College, Station Road, Erie, PA 16563; 814-898-7132. Her adviser is Pamela Botts, Ph.D., assistant professor of biology; 898-6105. Borgia's research was funded by a summer fellowship from the National Science Foundation. She has also received the Sylvia Stein Memorial Space Grant Scholarship to use satellite technology to examine ecosystems and track environmental changes. Vicki Glembocki is a former Research/Penn State intern and current associate editor at Pitt Magazine.