A Loudoun County subdivision that is home to more than 4,000 houses, 13,500 people, a Food Lion and a McDonald's has been named a Community Wildlife Habitat by a national environmental group.

At a neighborhood festival today, the National Wildlife Federation will award the certification to the South Riding development, the sixth community in the country to receive the distinction. The award is based on the 2,000-acre subdivision's five-year project to register individual back yards with the federation and make the development's common areas environmentally friendly.

The certification is meant to applaud the effort, not provide a stamp of approval for particular kinds of suburban growth, said David Mizejewski, manager of the federation's backyard habitat program, which runs the community certification. "As a general rule, the National Wildlife Federation does not support unsustainable development. Whether South Riding fits that definition, people could probably debate," he said.

Founded nine years ago, South Riding is one of several large planned communities that have contributed to Loudoun's ranking as the nation's fastest-growing county. When it is built out, South Riding -- just south of Dulles International Airport -- will contain more than 6,000 homes.

For residents who worked hard for certification -- handing out literature at community events, recruiting local businesses, creating an elementary school garden to attract birds and butterflies -- the award is a sign that people and wildlife can coexist in the suburbs.

"It's a good demonstration that urbanization doesn't have to destroy anything," said Mary Kay Smith, who chairs South Riding's wildlife habitat team. "We have deer, rabbits, fox. They're not chased out by the community. They have a place."

Their place must be within reason, Mizejewski said. Although the federation urges urban and suburban residents to learn more about plants and animals native to their areas, it advises homeowners in some places to remove bird feeders because they entice bears out of their natural habitats. "That surprises some people," he said.

Nevertheless, simple actions can help preserve disappearing species of insects, birds and plants, he said, and the certification recognizes those efforts. Although the South Riding project was initiated by the community's developers, it has been largely taken over by residents, and Mizejewski said the award reflects their hard work.

Mizejewski said he must guard against the award being used in eco-marketing by developers, who call frequently to ask about the program. He recalled one inquiry from planners of a tourist resort in Puerto Rico. Only later did Mizejewski learn that others at his organization were fighting that resort because they feared it would destroy turtle nesting grounds.

The federation also has certified Reston, where the group is based. Arlington is one of 17 other communities nationally that have signed up with the group and are working toward certification.

In South Riding, 107 families have registered their back yards as wildlife habitats, meaning that they provide food, cover, water and places to raise young. Volunteers put together a thick binder for teachers at the elementary school to show how to integrate the school's outdoor habitat into lesson plans. The community's proprietary has registered habitats at model homes and near the community's town hall. It also has planted vegetation as buffers around ponds, to prevent fertilizer runoff, and has committed to mowing common areas only once a year, providing high grasses for wildlife.

When Beverly Ricci moved to South Riding from New Jersey 31/2 years ago, she had mixed feelings about living in a new house in a new development, she said. Ricci's former home was more than 100 years old, and as a biologist, she had long had interest in the environment.

But the good thing about a new community, she said, is that its philosophies and habits are being shaped. By educating her neighbors and urging the practices advocated by the federation, she can influence how people think about the world around them, she said. Already, her two children delight in watching the insects and birds drawn to their backyard habitat.

"I think the more congested the suburbs get, [the more] you need to feel some of that greener space," she said. "People have to go somewhere, but so do the animals."

Residents worked on a school's outdoor habitat to attract insects and birds.The South Riding subdivision in Loudoun has been named a Community Wildlife Habitat by an environmental group. A hill behind the community's Little River Elementary is covered and planted to prevent erosion.