Four-year-old Sean Wood clutched his flashlight and bent over the stream bed, peering through the dark in silent amazement at the neat mounds made by crayfish and delicate hoof marks left by drinking deer.

As others clustered around, one overly anxious explorer announced the origin of another track in the mud: "That's from a tennis shoe, I'm sure of it."

Fact was, they weren't exactly roughing it on the one-mile nighttime nature hike in Fairfax County's Burke Lake Park. But the signs of civilization didn't hinder the frontier spirit among the 30 in attendance.

And the less-than-stealthy approach to wildlife watching still allowed all to enjoy the graceful dance of a great blue heron along the lakeshore as swallows swished by overhead.

"Listen for the sounds of the night," whispered Elianne Lieberman, a Fairfax County parks naturalist, trying to curb excited voices and jostling. "You'll hear the crickets going and the frogs calling."

Members of the group, half of whom were children, were participants in a journey that included flashlight views of various habitats, ranging from manicured lawns to wooded poison ivy thickets and soppy swampland.

Along the way, endless questions ensued -- "What's that moving?" "Why does it smell funny?" "Are we going to see bears?" -- and imaginations were given free reign for the evening. In a rush to solve the mysteries of the night, children retrieved half-buried bottle caps and carefully examined automobile tire tracks.

Passing by an edge of dense woods, the guide described how many common plants are edible. Lieberman's recipes for stir-fried day lilies and rose hip or sumac lemonade brought mixed reactions from the crowd. "Oooh. Blech," commented one listener.

As the sun disappeared, young Wood was asked if he wasn't wary of wandering into the night. "I'm not scared," he pronounced bravely, before adding, "well, maybe just a little bit."

His mother, Colleen Wood, had brought her two sons camping at Burke Lake and joined the night hike in hopes of getting some exercise before turning in. "Hopefully, this will be a nice wearout," she said with a smile as her boys romped ahead.

A close look at bird tracks revealed a city slicker in the group. "Maybe it was a pigeon," a boy said, then, "or an eagle or a hawk."

Lieberman knelt beside a stand of Indian pipes, explaining that the flowering plants are white from stem to stamen because they don't have chlorophyll. Flashlights shining into the woods also captured mushrooms along the moist forest floor.

As the group approached the marsh leading to the lake, Fairfax County natives noticed that the swamp has begun overtaking the open water area. Lieberman confirmed their fears, explaining, "All lakes are shrinking, but most will take hundreds of thousands of years to disappear." Decaying plants actually create a soil-like layer under water on which thick aquatic vegetation grows, she said.

Parental questions were answered faithfully. No, the lake is not a source for drinking water, Lieberman said, and yes, it is important to be aware of the potential for rabies in wild animals.

Hiking home from the lake along the same path, participants carried shells and feathers, souvenirs of their journey. Two boys stopped to point a small telescope at the sky, hoping that the help of a flashlight might bring the moon closer to their grasp.

Back at the parking lot near the park's amphitheater, members of the group prepared to part ways. Lieberman announced that the trip netted only one firefly, and warned youngsters always to put holes in their jars when catching the insects because their illuminating apparatus depends on oxygen. The lighting by fireflies is a mating call, she explained, with "the duration of the flashes and the pauses in between identifying the various species."

Lieberman invited the visitors back to the park, for any of the Fairfax County Parks outdoor education programs running Wednesday, Friday and Saturday evenings, and Sunday afternoons throughout the summer. Topics will include stars, hawks, owls, snakes, turtles, cooking at a campsite, and general tours of the park on the miniature train, she said.