Every day this Christmas season, as he has for the past seven years, Vaughn Barkdoll enters a small shelter at the back of a plywood manger protecting a nativity scene located near the Ellipse.

Barkdoll, the director of public works for Prince George's County, shucks his business suit for brown corduroys and a heavy work shirt and is ready to tend the spirit of Christ in Christmas as part of the national holiday pageant.

Across the street, the official Christmas celebration is a festive winter carnival dominated by the bold lines of the Washington Monument in the background and the giant national Christmas tree near the center of the Ellipse.

Children drag adults past ranks of small trees, each named for a state, to get to the large petting zoo where they can touch the dozens of goats, lambs and other furry animals.From the loudspeakers, Tony Bennett cajoles them not to pout because "Santa Claus is coming to town," his recorded voice ringing clear across the frosty Ellipse.

Off the main pathways of the observance, and much more quietly, Barkdoll and about 15 other parttime volunteers tend two small sheep, a burro and the cracked plastic figures of the Holy Family in the manger. They watch over the scene from Dec. 18 through Jan. 4.

Barkdoll, 38, formed the American Christian Heritage Association which built the manger, after a September 1973 court ruling prohibited the National Park Service from including the creche in its then 19-year-old pageant, finding the Christmas scene a violation of the First Amendment's guarantee of separation of church and state.

Barkdoll's manger scene is 60 feet long and about 14 feet deep, stained in dark brown, with a low chain link fence around the front.A homemade wooden "Nativity" sign rises above the display against the backdrop of the long grey Commerce Department building.

On a typical day, Barkdoll drove from his home in Greenbelt at 6 a.m. to check the nativity scene, got back to his office in Upper Marlboro by 7 a.m., made another midday round trip to check the scene and returned again to the park for a 6 p.m. to midnight vigil.

He has devoted himself to the manger exhibit every Christmas since 1973, and has not taken a holiday trip during that time although his wife and two children have gone without him once or twice.

Writing in a fund-raising pamphlet, Barkdoll explained why he puts in the time and work: "I can remember going to the Ellipse as a child to see this gigantic Christmas tree with ornaments the size of basketballs and thousands of twinkling lights. There was always Santa's reindeer . . . the Yule Log where you could warm up those frozen fingers and toes . . . and yes, there was always the nativity scene with the Christ child lying the manger.

With the help of friends and the Prince George's Knights of Columbus, the American Christian Heritage Association -- which consists chiefly of Barkdoll, who is executive director and the only year-round, full-time member -- put on the first two-week display in 1973. It cost $9,000 that year, although only $6,000 in contributions arrived.

Since then the annual operating cost has run about $3,000, donations always somewhat less. Barkdoll has made up the difference himself every year. Last year the deficit was just over $1,000, but he hopes to get his money back from surplus donations one of these years.

"A lot of people (write) and wish us good luck. I've had some people send a quarter wrapped in paper towel, saying, 'That's all I can afford.' Retired people and all," said Barkdoll.

"If we ever get rich, I'll pay myself back," he added. "We're very lowkey."

Only the figures of Mary, Joseph and two shepherds attend Barkdoll's baby Jesus; the wise men and another shepherd were cracked beyond recognition after 25 years of use. Barkdoll said new ones would cost almost $4,000.

"The figures seem to be in disrepair," said Nick Rizzo, a visitor from California, as he leaned against the fence surrounding the manger, his eyes tearing in the wind. Rizzo said he had not gone to church since he finished parochial school four years ago, but thought the creche deserved more attention.

Judie Craine of Takoma Park stopped by on her lunch hour after visiting the petting zoo across the street. She said the frolic of the children and the decorated trees seemed more like Christmas to her than the creche set off to the side.

"I don't know if this is bringing the right kind of emotions out," she said. "But the petting zoo is packed. Everybody is over there. It has a humanity, a kind of warm feeling, you know. This seems awfully isolated. It's too bad. Who's going to know it's over here?"

Barkdoll and a young helper rearranged some of the animals' bedding hay and checked the supply of straw they comsume at $3 a bale. He fed the pot-bellied burro some horsecrunch, a sticky mixture of cracked corn and molasses.

The weather, Barkdoll said, plays a big part in the attendance. "Most of the traffic comes by at lunchtime, business people shopping around," he said. But when it's cold or inclement most people stay in their offices.

"We literally could not dig the 4-by-4s out one year. We had to dig up the electrical wires with a truck. One year this place was a solid sheet of ice," he said, back inside the warm little room of sheet rock walls behind the display.

Back behind the scene, with a pot of coffee brewing on a shelf near a cot with a foam rubber mattress, Barkdoll could not really say why he stays with his time- and money-consuming project.

"I'm not a real religious freak," he said. "I believe that this country was founded on freedom of religion. I don't disgree with the separation of church and state, but when (the Nativity) was removed from the pageant . . . I said somebody's got to do it. It might as well be me."

He will continue taking his turns on the cot until Jan. 4, behind the simple display of his convictions, listening for footsteps on the wooden runway leading to the scene, especially late at night.

"That's when it's interesting," said Barkdoll. "Then you get a young couple, maybe at 2 or 3 a.m., maybe coming from a party. They just stand there, looking."