He had never painted a duck before. Except for Donald and Daffy, he didn't really know what one looked like. But when Nolan Haan heard about the Federal Duck Stamp Contest, said to be the richest art competition in the world, he got educated in a hurry.

"I went down to the Smithsonian to look at a stuffed duck they had in a display case," says Haan, a 34-year-old self-taught painter and writer who earns his daily bread by waiting tables at an Italian restaurant in Bethesda. "It was kind of a weird looking duck . . . but I needed something to paint."

Earlier this month, Haan's painting of that duck, a King Eider, earned him second place in the contest and a way out of the restaurant business.

"Two weeks ago I was a nobody. Now agents are calling me up. I'm invited to show at galleries. A hundred doors have opened," says Haan, a red-haired, blue-eyed former Peace Corps volunteer. "I think my days (as a waiter) are numbered."

The duck stamp competition, held every autumn in an auditorium of the U.S. Department of the Interior building in Washington, is the World Series and Super Bowl of art contests. This year five judges looked at more than 1,500 paintings from wildlife artists before choosing one that will be made next year into a stamp that anyone 16 years or older who wants to hunt waterfowl must purchase.

The winner gets nothing from the government but a free set of 30 stamps. And the $7.50 price of the stamp is used for waterfowl conservation. But first place is still worth more than $1 million to the winner from the sale of reproductions to art collectors.

"It's nice that we are elevating unknown artists to national acclaim," says David Klinger, an official at Interior. "The government in a sense is making a millionaire."

Last year's winner, David Maass of Minnesota, had 22,500 prints made of his painting of three canvasbacks in a storm. They sold for $135 each for a total of more than $3 million. Wholesalers, retailers and an agent got most of that money. But Maass' share was hardly shabby.

"The pie gets cut into lots of little pieces, but it's still very lucrative," concedes Phil Scholer, this year's winner who is also from Minnesota. Until this month, the 31-year-old Scholer was a professional sign painter. His best known works are unsigned pieces, such as Joe's Bar and Grill, Happy Center Horse Ranch and Barbecues on Special, which appear on the nation's highways.

The duck stamp program was begun during the Dust Bowl days of the early 1930s when drought threatened to dry up the nation's prime waterfowl habitats. President Franklin D. Roosevelt and Jay (Ding) Darling, a Pulitzer Prize-winning cartoonist and outdoorsman, joined forces to create the Federal Migratory Bird Hunting and Conservation Act of 1934.

Since then, sales of the stamps have raised $400 million for the purchase of 3.5 million acres of prime waterfowl habitat.

From 1934, when Darling drew the first federal duck stamp featuring a pair of mallards, until 1948 the stamps were drawn by federally commissioned artists. The contest began in 1949. But the artists did not begin to really cash in on winning it until the 1960s. And it wasn't until recently that anyone but collectors and a small group of artists became aware of the money to be made in painting birds. In 1976, for instance, fewer than 300 artists submitted entries.

The quality of the art has increased dramatically in the last decade. The ducks entered in this year's contest, floating or flying, displayed a breathtaking sophistication.

"When I saw the other entries, my hopes went out the door," says Haan, who taught himself to paint 10 years ago while serving in the Peace Corps in Indonesia. "I thought if I place in the top 20, luck is with me."

Haan handicapped himself by choosing to paint a sea duck that is little known outside of Maine and Alaska. By painting a closeup of the Eider's head, he also flew against the tradition of depicting full-bodied birds. Despite those choices, he managed to earn perfect scores of 10 from two of the five judges. If a third judge had not scuttled him with a score of 4, Haan probably would have won the contest.

If Haan didn't know a mallard from a moose before the contest, he has been educating himself ever since. He makes regular pilgrimages to Maryland's Eastern Neck wildlife refuge and jokes that he has spent so much time at the National Zoo's duck pond, "they're giving me a cage I can sleep in."

"I'm definitely concentrating on ducks for a while," says Haan. "I love those birds."