Molly Pallavicini has seriously considered selling her house to get away from her new neighbors. "They're disgusting," she said. They carry on in public. They hiss at each other. They use her driveway as a toilet.

"They are big black and turkey vultures," Pallavicini said, enough to darken the sky when she drives home from work about 5 p.m. to her house in Staunton, Va. "I've had as many as 50 of them at the house. When they take off and leave, it's such a loud noise, like a wreck or something."

Staunton, population 24,000, is the latest winter destination of federally protected vultures - about 500, according to the U.S. Department of Agriculture Wildlife Services, more than ever before. After trying unsuccessfully to scare them away for weeks with fireworks, the USDA recently turned to firepower, killing at least two dozen each Monday and Tuesday night, and still the vultures haven't retreated.

Each year, this goes on with vultures and various birds and other wildlife in cities across the nation. Large numbers of vultures have also roosted in Leesburg and Lynchburg, Va., and recently in Columbia.

European starlings often invade Indianapolis and Omaha; they also flock to dairy farms, where they eat much of the food set out for cows and drop excrement in the rest. Canada Geese foul every golf course and park in the District and numerous states with their waste.

The USDA is the only agency authorized to kill vultures and other birds protected by the Migratory Bird Treaty Act of 1918. A felony if convicted of killing a protected bird, the penalty is up to $200,000 for an organization, $100,000 for an individual and/or up to one year in prison.

Public works officials in Staunton and residents like Pallavicini can look at vultures but can't touch them. Vultures, of course, aren't much to look at. Dressed appropriately in black plumage, they serve an important role as the undertakers of the natural world, scarfing down carrion.

Vultures are what they eat, Pallavicini said. They stink, and they're mean. On New Year's Eve, they fought on her lawn. The next morning, "I walked out . . . and one was in my back yard, split open, bloody. I had to go out and get it so my dogs wouldn't eat it."

A USDA spokesman said vultures are the only birds that can't be banded for tracking because their excrement - which coats their legs - would quickly corrode the hardware. Their waste matter is so strong that pine needles have fallen off trees in Staunton where they roost overnight.

Staunton's problem started the way it always does this time of year in many cities. Like other living things, vultures get cold in remote country areas. Staunton and other cities are attractive because they're slightly warmer.

Late in December, the birds swooped into the northern sections of the city, including Baldwin Acres and Gibbs Hill.

At City Hall, phones at the public works department lit up. Director Thomas Sliwoski gave every caller the same spiel - basically, there wasn't much he could do. The birds usually fly off when the weather warms, but officials in Staunton didn't want them to get comfortable.

"You come here after 3:30 [p.m.], and you can see masses of black in the sky with them just circling," Sliwoski said. "For some reason, they like rubbery stuff. They like pool covers and windshield-wiper blades. People are afraid to put out their cats and dogs."

Homeowner Scott Koehn had a bright idea to chase away vultures. He stepped outside his split-level home in northern Staunton with his son, Andrew, 9, and started firing paint balls into their roost in pine trees.

A single vulture sailed into action, swooping toward them. "It vomited on my son," Koehn said. "It was like a half pound of ground beef on his shoulder. It was so disgusting. We got it off him. Got his shirt off. And got him to stop screaming."

Sliwoski had a better idea. He called Scott Barras, state director for the USDA Wildlife Services program in Virginia. The USDA seeks to resolve an estimated 200,000 conflicts yearly between wildlife and man in the United States.

In 2009, the agency dispersed more than 27 million wild animals from communities and farms and killed 4 million, according to a report on its Web site. Black vultures and turkey vultures accounted for 121,000 of dispersed animals and 4,000 kills. But Barras's hands were also tied. Although his agency is authorized to kill vultures, he can't march his workers into neighborhoods with their guns blazing. The USDA is trying to resolve the problem without violating the spirit of the migratory bird act.

"You have to understand what the law is there to do," said Kevin McGowan, who studies birds at the Cornell Lab of Ornithology. "That was the law that stopped people from market-hunting birds and driving them to the brink of extinction."

USDA took plodding steps to remove the birds and their ammonia-like smell.

Step 1 in late December: Scare the bejesus out of them with bottle rockets that shriek and pop. The vultures scattered for a few hours and flocked back.

Step 2: Hang dead vultures in effigy in their roost the way Vlad the Impaler, the original Count Dracula, once did to his enemies in Romania. That troubled the vultures but not as much as hanging out in the cold countryside.

Step 3: Blast them.

Tuesday night, Pallavicini returned home from work about 5 p.m., when the birds start to gather around her house after a day of searching for food, and she ran into a USDA worker.

"He's carrying bags out," she recalled. "He says, 'I think I got three, maybe four.' I said, 'They're dead in there?' He said, 'Yeah.' "