IT LOOKS VAGUELY suspicious. At six o'clock in the morning, two scruffy-looking men and shambling up the path between the C & O Canal and the sylvan glen that presses against the eastern bank of the Potomac. Sometimes they creep like children playing Indians. Sometimes they make cooing signals into the bush. Occasionally, they whip out Zeiss binoculars and peer at objects invisible to the untrained eye.

Spies? Two old coots having a rip after an all-night bringe?

Neither. It's James Schlesinger, White House counsel on energy, and Sir Peter Ramsbotham, the British ambassador to the United States. They are stalking an elusive warbler.

Washington birding - birdwatching to the uninitiated - includes some of the city's most powerful men. Birders crop up where you least expect them: in the diplomatic corps, the military, and in the halls of Congress. Their roster boggles: Thomas Jefferson, John Quincy Adams, Teddy Roosevelt, Everett Dirksen, Prince Philip, Prince Bernhard, John Foster Dulles, Edna St. Vincent Millay and Rachel Carson. Elliot Richardson birds with Schlesinger; Schlesinger birds with Ramsbotham; Ramsbotham birds with just about everybody. Senator Charles mcC. Mathias Jr. and his wife Ann haunt Chesapeake Bay, taking in the waterfowl, as does Russell Train. Dillon Ripley likes the upper C & O Canal, and Senator James Buckley trundles around the corner from his house to Battery Kimball Park.

In addition to what you might call birders-in-high-places, Washington can lay claim to a large contingent of the best birders in the world. They seem to seep out of the woodwork at places like the Smithsonian, Patuxent Wildlife Research Center, and the Fish and Wildlife Service.

It is an extremely popular activity which hardly anyone knows anything about.Most people think of birding as an eccentric pastime for a great many nuts - some seven to eleven million Americans, by the best count. A few years ago, Nathaniel Reed, then undersecretary of Interior and a birder, said there are more birders in this country than fishermen and hunters combined. That's a lot of eccentrics.

Non-birders tend to think of birdwatchers as meek sorts. Nothing could be farther from the truth. Down at Dyke Marsh, one can see osprey swooping over man-tall grasses, eagles napping on air currents and great blue heron posing as if for cheesecake layouts. A pretty picture. But murkier cross-currents are at work as well: The marsh is a magnet for birders, and therefore for strong egos and fierce competitiveness. It is not always the pleasant, relaxing, rural pastime it might seem. And it is hard work: Birders habitually rise before dawn (early morning is the best time to catch most birds' acts), slog through swamps and marshes, climb mountains and brave below-freezing temperatures to satisfy their passion. No birder of any worth would laze around in a bucolic field waiting for an indigo bunting to flit by. He'd march right out and track the bird down.

Theoretically it is the most democratic of sports, because anyone who wants to can take it up. It is basically a cheap activity, requiring nothing more than a paperback field guide and a pair of seven-magnification-by-thirty-five-millimeter binoculars. But it takes time to become really skilled. It helps, therefore, to either be a child, a retired adult - or rich.

Washington's elite birders are a rarefied little group, brilliantly educated and moneyed. But most of these fellows would eagerly haul themselves out of bed at five in the morning to drive three hours to Chincoteague, Virginia, to tag along with a blustering government bureaucrat who comes on like an overenthusiastic Boy Scout leader - Paul DuMont. DuMont is the world's most illustrious birding lister, for he has seen more species of birds on the North American continent then any other person, dead or alive. He seems agreeably pleased with himself, although he is forever running off to Alaska to add a misplaced Asia species to his long life list. Of Schlesinger and Richardson, DuMont says: "Neither of them are what you would call 'good birders.' They're just average. I saw Schlesinger the other day and he rushed up to meet me. He seemed very excited. I didn't recognize him; he had more reason to recognize me than I to recognize him."

There are other superstars on the Washington birding scene: Floyd Murdoch, a good-natured high school principal who in 1973 set the American Birding Association record for North American species sighted in a single year. Claudia Wilds, who took up birding only five years ago when an inheritance enabled her to quit her job, has become the aknowledged best woman birder in Washington. She records the Voice of the Naturalist (652-3295), a telephone message which offers advice on where to spot the rarest bird of the week and other nature treats.

Chandler Robbins, a new hero of birders for his compact Birds of North America , one of the two indispensable field guides, works at Patuxent Wildlife Research Center as a wildlife research biologist studying migratory non-game bird populations, and does most of his birding these days on the Patuxent grounds. The lowest-key, most soft-shoe guy imaginable, Robbins also enjoys taking monthly chartered boat trips with Richard Rowlett of Laurel, Maryland, who regularly turns up "real goodies" like the yellow-nosed albatross, Sabine's gull, Manx shearwater and razorbill lark, none of which had evern been spotted in Maryland before Rowlett did.

And Roger Tory Peterson, the biggest name in birding since John James Audubon and author of the indispensable field guide (The Field Guide to the Birds ) until Robbin's book came out a few years ago, is an old Washington hand, having lived here for eleven years after the Second World War.

It was Peterson who got Elliot Ricchardson interested in birdwatching when he had Richardson as a student at the River School in Brookline. "The thing that got me started," says Richardson, "was a contest he initiated when he was my art and drawing teacher in seventh grade. The purpose of the contest was to see how many birds we could identify between spring vacation and commencement. Well, I threw myself into this contest. I started getting up earlier than ever, searching for birds. I finally saw about 130 species; not a lot for an experienced birder, but it was a lot for me - and I won."

Richard Vine flips his legs over the arm of his puffy upholstered chair and curls up, cat-like. It is an unexpected gesture. He is Deputy Assistant Secretary of State for European Affairs - and "a total nut about birds," he admits.

"When I was in my twenties, I was stationed in Tel Aviv," Vine says. "I was driving to Jerusalem on a beautiful, cloudless day. I went through a valley which was a carpet of wildflowers. It's unbelievable to see that short, swift spring in the Middle East. Just as I passed, a flock of about 2000 white storks fluttered down and landed in the field nearby. I stopped my car. I walked up to them, and they let me touch them. It seemed almost mystical. When I got to Jerusalem, I was still taken with what had happened, and I asked the fatal question: Why? Why did 2000 whtie storks land in that very field at that time? By the time I got the answer - and found out that they were migrating and that it was perfectly natural - I was hooked.

"Now I'm never bored; I don't have to go any place to birdwatch," he says. "Once I was at a Dallas-Redskins game, and I was probably the only person in the stadium who noticed a merlin flying overhead. Not long ago, I was in the Smithsonian tower trying to install barn owls. Just at midnight, I looked up, and a black-crowned night heron flew right across the mall. For years, my wife was trying to see her first pileated woodpecker. Where do you think she saw it? On a telephone pole on Connecticut Avenue one morning when we were walking to church."

Sir Peter Ramsbotham didn't discover birds until he was at Oxford. "They had marvelous gardens," he says. "I could walk about in there for hours. When I was about nineteen, I had a friend who had a falcon. He taught me bird songs - I suppose I've loved it ever since."

Ramsbotham, such a Kriss Kringle of a man that his refined British accent comes as a surprise, had cheerfully made up a list for me, as a student would for a teacher, of the "high points" of his American birding experiences. In Phoenix, he saw his first roadrunner "with a lizard in its mouth." In Florida, "I was privileged because I saw and photographed the rare Everglades kite. I also saw a pomacea, a fresh-water snail, which exists for the kite to eat. It is a very great privilege for the snail."

The ambassador frankly uses birding as a tool to connect with "average" Americans. "In this job," he says, "the pomp is very thick and hard to avoid. Birding is a way of cutting through and meeting people. You put on old, torn clothes, tramp about in the muck, and people tend to forget that you're an ambassador."

Then there is the curious case of Jim Schlesinger, who is the best-known non-professional birder in town. Ask anyone. "I've gone two or three times with Jim Schlesinger," says Ramsbotham. "Up around Seneca. He really is frightfully good - one of the best."

"I've encountered him only once," said Shirley Briggs, colleague of Rachel Carson, Louis Halle and Roger Tory Peterson. "I was walking up near Seneca, on the canal. He was with his son and a remarkably disciplined dog - a dalmatian. He is a very good birdwatcher."

"I'm not in the same league as Jim Schlesinger," Elliot Richardson admits, somewhat ruefully. "When he was Secretary of Defense he would see to it that a Defense trip would bring him to a patch of New Mexico land with a rare species on it, and he would always arrange to go birding."

The odd thing about all this is that, in spite of the fact that every birder in Washington knows that Schlesinger is a top-flight birder, he seems to try to keep it a secret. During his days at the Department of Defense, he flatly refused to speak about it. He thought it was bad for his image.

Like any sport, birding is rife with conflict, battle, schism. A common thread which weaves through birding tales is the theme of war. Christmas counts and spring and fall censuses are plotted, and carried out, like military campaigns. Historically, many of the most important amateur ornithologists have been military officers, especially in Great Britain, where the British Naval Birdwatchers Society, presided over by Rear Admiral Sir Nigel Henderson, is composed of the cream of the British Navy. The late Field Marshal Earl Montgomery, who launched a brilliant defeat of the Germans at the battle of Alamein in Africa, was another member of the birdwatching brotherhood. And Dillon Ripley, a noted authority on the birds of India, was an intelligence agent in Southeast Asia during the Second World War.

Some people get into birding in prison. "One of my best friends became interested in birds when he was in prison," says Ripley. "He had been captured by the Turks, and he told me later that the only thing he could do was learn the birds that sat on a telegraph pole outside the prison wall.

"And Mrs. Gandhi told me that when she was jailed by the British, she devoured my book on Indian birds. She began to notice the birds perching on the trees, and became quite excited about it."

We have talked here of many men who bird, but not many women. This may surprise a few of you who think of birdwatchers as little old ladies in tennis shoes babbling inanities in a New Yorker cartoon.Here we have an interesting definition problem. Birding, as opposed to birdwatching, is a strong male preserve. Birders are supposed to be serious - people who make list, get up early, make themselves uncomfortable and are highly skilled at recognizing virtually any bird in the field by sight or song. Secretly, however, many male birders seem to believe that "birdwatchers," those who putter with the idea of birding but never bother to learn the birds' names, are mostly women.

"Birding, at its highest levels, is completely dominated by men," observes Claudia Wilds, who is definitely a birder herself. "A woman is automatically considered inept until she proves otherwise. I guess that's why I never went birding with anyone during the first year I started birding. When I appeared on the scene, I wanted to be really impressive."

Unlike men, few women take up birding when they are children. No one really knows why, but there are some fascinating theories. "Do you suppose it goes back to the natural submisiveness of the female?" suggested Paul DuMont. "Perhaps a gal might be afraid to tromp off through the woods by herself; perhaps she'd rather stay at home. Whereas boys have in their souls the urge to roam."

Charlton Ogburn, author of The Winter Beach and a number of other books, figures it another way. "Boys have a tendency to be collectors; to try to get a grip on the wonderful variety of things in the world." What about girls? "Boys just get this passion for birds. I don't think it's in a girl's nature. Of course, girls have a passion for horses. Horses seem to do the same thing for girls as birds do for boys."

Some people bird for the challenge of listing; others bird to satisfy their fascination with science. Ornithology is the only remaining branch of science in which an amateur can make a solid contribution. Most people, however, bird because it gets them out of doors into the sheer beauty of the world. Birdwatching gives us a fragile connection with our rural roots, which are too frequently forgotten in the concrete webbing of our cities.

More than anything, birdwatching is one of the few things you can set out to do which, almost every time, will swell your soul. "You feel a spell; you sense the richness of life," says Charlton Ogburn. "Nature speaks to you through birds more articulately than anything else."

"I always think of the Earl Grey of Fallodon," mused Sir Peter Ramsbotham. "He was the British foreign secretary during the First World War. In his old age, he went blind. Every day, his family would lead him out to a lake on his great estate, and he would sit for hours and listen to the birdsongs. It was like poetry."