There’s a reason Filene Center concert-goers probably don’t think of Wolf Trap National Park for the Performing Arts as a place where wolves are trapped. According to the National Park Service, which runs the sylvan performance space, the wild canines vanished from the area about 1739.

Yet the 130-acre expanse is not without wildlife. The Northern Virginia chapter of the Audubon Society is halfway through a year-long survey of the park’s birds.

“Our job is to walk this trail for a couple of hours and mark all the species we can identify,” said the society’s Bill Brown, who coordinates the 28 volunteers. “We’ve found about 90 species so far. And we haven’t had spring migration yet.”

Brown calls the survey “a true citizens’ science program. It gives a good idea where birds are and shows where numbers might be increasing.”

The final count will result in a bird list to be distributed to visitors by the Park Service. Although the gray-haired birders are clearly not of the generation that grew up with computers, they’re tech-savvy enough to record their sightings on

BillBrown of the Northern Virginia chapter of the Audubon Society inspects a feather found along the Wolf Trap Trail. (Mark Jenkins)

The path hiked one cold November morning by Brown and three other birders, Mark Leckert, Jeanne Leckert and Mike Corrigan, is new to the park. Developed in partnership with the Potomac Appalachian Trail club, the 2.5-mile trail was begun in 2010 and is “just about done,” said Phil Goetkin, Wolf Trap’s land manager.

The trail, the bird survey and other initiatives are part of a redefined mission for Wolf Trap. “We’re becoming more of a natural history park,” said Park Superintendent Karen Pittleman.

“The Filene Center has been our focal point,” Goetkin said. “We are a national park, though, and a lot of people don’t realize that.”

“So we really started looking at our natural resources. We started looking at sustainable landscape techniques.”

That meant reducing the land that’s mowed — down to 25 acres from 35 — and replacing invasive species with native ones. The most conspicuous example of the change is the “native meadow” in a hollow near the Filene Center entrance.

“Nobody ever noticed it was there,” Pittleman said. “Yet we mowed it, and we fertilized it. Now everybody notices it.”

“At a time when budgets are being reduced, having less manicured land is really a saving for us,” she added.

Another goal in returning formerly mowed land to a natural state, Goetkin said, was to create habitat for native species. “We started to attract a lot of insects, birds and animals, and then we said, ‘Well, we need to know exactly what’s showing up here.’ ”

So the Park Service turned to the Audubon Society for the bird survey. It’s also doing studies of bees and butterflies in association with the Smithsonian and the U.S. Geologic Survey.

The new trail generally follows the borders of the park, with one switchback through the largest area of uninterrupted woods. The area it traverses is not exactly wilderness. Once the Filene Center is out of sight, the Dulles Access Road comes into view. Farther along, nearby suburban houses can be seen.

Also disrupting the pastoral vistas are Trap Road, which bisects the park, and almost 3,000 parking spaces. “We’re very green,” Pittleman said. “Except when it’s time to leave at night.”

Despite these intrusions, Wolf Trap abounds with flutters and chirps. “Because the park encompasses a variety of habitat and has remained largely undeveloped, it attracts and shelters a much larger variety of birds than the highly developed residential and commercial areas that predominate in Fairfax County,” Brown said.

That November morning, the spotters identified titmice, Carolina wrens, starlings, pigeons and chickadees. They also glimpsed larger birds, including a pileated woodpecker, a bald eagle, a great blue heron and, unusually, a barred owl.

“Owls are hard to see,” Brown said. “They’re probably always here. But it’s very rare to see an owl in daylight.”

In three hours on one-quarter of the trail, the Audubon crew counted 28 species, which Brown said was on the high side of the average number. They also watched a large buck on a ridge, and rounded a pond where a beaver had built a lodge.

The hike began to the tune of a non-native species: a motorized leaf-blower clearing the parking lot behind the Filene Center. The machine is not yet a rara avis at Wolf Trap, Goetkin said.

“In the areas where we have a lot of people coming to events, we have maintained turf. That’s what people expect,” he said. “But more and more areas are no-mow zones. So we’re doing a lot less blowing than we used to.”