WASHINGTON is perpetually atwitter with political birds: hawks and doves, peacocks, ostriches, the occasional phoenix. They're so noisy and colorful we tend to lose sight of the real thing. More than a quarter of all the kinds of birds found in the U.S. can be seen inside the Beltway over the course of a year -- over 300 species.

"This is a very rich area for birds," says Erika Wilson, who often compiles and narrates the Voice of the Naturalist, a weekly telephone recording of bird sightings in the area sponsored by the Audubon Naturalist Society (652-1088). "One reason is that we have the Potomac River, which is part of the Chesapeake Bay." The river's a migration route for some birds, a wintering spot for others and, for creatures such as the great blue heron, a year-round home.

"Washington itself is on the fall line, the border between the coastal plain and the piedmont. There are different kinds of birds in each area, and because of that I speak on the Voice of the Naturalist about the lower and upper Potomac. You get a terrific variety of waterfowl on the lower Potomac because of the submerged vegetation."

Wilson points out that hydrilla, the vegetation that gets all the attention, is but one of several important bird-attracting plants in the river. Others include eel grass, milfoil and widgeon grass. All trap sediment, oxygenate the water and provide food and shelter to invertebrates that are a basic link in the food chain for birds and fish and people. From a birder's point of view, the same stuff that fouls your propeller and keeps you from waterskiing is the greatest thing since binoculars.

Migration goes on nearly all year here, with slow periods from mid-December to mid-February and again from mid-June to early July. "We're right in the middle of fall migration now," Wilson says. "There are a lot of warblers moving through, and they're folowed by the thrushes . . . Hawk migration is from September through November, and if you can find a good spot where hawks are moving through in numbers, that can be quite a spectacle. But you really need to be on the coast or in the mountains for that. For beginners, I think the arrival of ducks is a good starting place, because these birds are large, they're in this area and have very distinct characteristics." Some of the ducks presently in town: northern shoveler, American widgeon, ruddy ducks, mallards, black ducks, blue- and green-winged teal and wood ducks.

The bird that gets the most ink in our area is the bald eagle. Until the 1950s, when DDT residues in the food chain caused fatal thinning of their eggshells, bald eagles were fairly common in the region; since the pesticide was banned they are becoming so again. There has been a nesting pair at Great Falls on the Maryland side for two years. Virginia's Pohick Bay Regional Park, about 12 miles south of town, is a good place to go eagle watching.

If your image of birders as bookworms in cardigan sweaters persists, meet Bill Thomas, Audubon Naturalist Society member and sometime leader of bird outings. Sixtyish, with a craggy face that exudes character and a voice like sandpaper, he looks like a tugboat captain. When we rendezvous in the parking lot of the Belle Haven picnic area in Alexandria at seven on a Saturday morning, he's wearing black rubber boots, a red watch cap against the morning chill, binoculars, a clip-on compass in a shirt buttonhole, and a bag slung over his shoulder for his Peterson's field guide. He's also toting a Celestron SS60 spotting scope on a tripod nearly as tall as he is.

I introduce myself, telling him that I wasn't sure anyone would show up for the outing, as it was raining when I awoke at 6.

"Oh hell yeah," he says. "Unless it's ice or sleet or a wind above 30 miles per hour, I always come out. At least when I'm the leader." Our group this morning is small: Thomas, me and Betty Pasta, an English professor at UDC. "Most of the others are probably up in the mountains looking for hawks or upriver looking for warblers," says Thomas. "But I'll give you the straight skinny. We haven't had a north wind for a couple days, so there won't be many hawks. And we've got just as good a chance at warblers here."

Our birding begins at the water's edge. Thomas uses his binoculars to determine which birds he's interested in, then the spotting scope to zero in on them. There are 30 double-crested cormorants roosting on a drowned tree several hundred yards offshore.

"Those are the birds the Chinese use for fishing," he says. "They put a ring around their necks so they can't swallow large fish, only little ones. You probably saw movies about it when you were in school."

Glassing the small bay where Hunting Creek empties into the hydrilla-choked river, he quickly points out some American coots, several types of ducks and a pectoral sandpiper. Through his scope I can see the yellow eye of a great blue heron as it stalks fish with a stealthy, knees-first gait reminiscent of Groucho Marx. The mats of hydrilla cover this part of the river; through the scope they look as solid as asphalt.

"I've got a pied-billed grebe," announces Pasta, showing me a small, duck-like bird floating passively near a log that's standing room only for mallards. A caspian tern flies overhead, a sleeker version of a seagull but with a forked tail. Unlike gulls, they dive headfirst but seldom swim, Thomas says. A belted kingfisher hovers on rapidly beating wings, then plunges into the water.

After a while we get in our cars and caravan a short distance to a parking lot on Jones Point under the Wilson Bridge. Walking out on a sort of boardwalk behind the Hunting Towers apartments, we run into more blue herons, black-crowned night herons, snowy egrets and great egrets. Both species of egrets are completely white, but can be differentiated in that the snowy has a black bill and yellow feet (known as golden slippers) while the reverse is true of the great.

Elsa Porter, who lives in the nearby Ponte Vecchio apartments and has come out with her spotting scope to join us, informs me that Jones Point used to be a roosting place for thousands of snowy egrets in the early part of the century. They were so plentiful that this one colony supported a ladies' millinery shop in Alexandria, where their feathers were in such demand that they were finally killed off.

"Aw heck, we've got all kinds of birds here," Thomas says, chainsmoking as he screws his eye to his scope. "The waders are the high-interest ones, because there aren't many places you can see them this close up. Hear that? That's a yellowlegs. Let me check my Peterson to see if it's a greater or a lesser. Here it is . . . a three-note call: That's the lesser."

Porter shows me a sandpiper between two great blue herons, perched next to a styrofoam clamshell that once housed a Big Mac.

"It's either a semipalmated sandpiper or a least sandpiper," she says, thumbing through her Peterson. "See," she frets, showing me the plates, "it's either that one or this one." I tell her the two plates look identical to me. "I know. You can go crazy out here."

A little later she has found a male wood duck in full breeding plumage, a bird so brilliantly marked that even a first-timer is impressed. "Oh," she says. "The light's just right on him. And you can see his reflection in the water. That just makes my whole day." ORGANIZATIONS

AUDUBON NATURALIST SOCIETY --

Most of the birding organizations in the Washington area are run by volunteers who work out of their own homes. A notable exception is the ANS, located at 8940 Jones Mill Road, Chevy Chase MD 220815. 652-9188. ANS offers a bookshop and self-guided tours on its 40-acre headquarters/wildlife sanctuary. It sponsors classes, workshops and field trips on birds and other aspects of natural history for beginners to experts. ANS provides guided tours on its headquarters grounds by arrangement. ANS field trips are wide-ranging, both in the capital area and to places such as Hawk Mountain in Pennsylvania and to coastal points such as Delaware Bay and Chincoteague.

NORTHERN VIRGINIA CHAPTER

of the Virginia Society of Ornithology (VSO), P.O. Box 5424, Arlington VA 22205, publishes a newsletter with information about its weekly trips, most of which are in Northern Virginia. Write for further information or call newsletter editor Valerie Kitchens at 536-9310.

MONTGOMERY COUNTY CHAPTER

of the Maryland Ornithological Society (MOS). Publishes a newsletter six times a year with information about trips for members. For information, write Robert Caswell, 11626 35th Pl., Beltsville MD 20705.

SMITHSONIAN RESIDENT ASSOCIATES

offers periodic birding trips. Upcoming are an overnighter to Cape May October 17-18; winter birding in Prince George's County November 14; swans on the Eastern Shore December 6. Call Moya King, 357-2278. WALKS

VIRGINIA --

At 8 a.m. every Sunday of the year, barring only hurricanes or blizzards, volunteers lead two-hour birdwalks in Great Falls Park. Meet at the visitor center. 235-3884.

MARYLAND --

Every Wednesday at 10 volunteers lead two- or three-hour bird walks in the C&O Canal National Historic Park. Meet at Great Falls Tavern in the park. Walks are also usually conducted on the third Sunday of the month. 229-3613.