For several years my bird-watcher companion and I have been hiking the C&O Canal. No, not wearing backpacks and setting records. We're doing it the easy way -- in segments, lock by lock. On a Saturday or Sunday, preferably early before the crowd arrives, we drive to a parking lot on Canal Road. Then we hurry to explore a section missed on earlier occasions.

The canal on any given day has something for everyone. For me, a people-watcher who hides her avocation behind a Field Guide to Birds, as well as for my friend, it's a constantly changing scene, always enticing. And while eash season the canal assumes a different personality, basically it remains the same: always the water, the wildlife, the beauty, the people -- and sometimes the politicians.

A little over a year ago on a Sunday afternoon we saw the then-president and his first lady jogging on the path in full splendor. Motorcycle policemen ahead, sweat-suited Secret Service men jogging all around. Ten paces back, the first lady in an attractive outfit and looking spiffy. Bicycling Secret Service men and walkie-talkies in front and back of her. More motorcycles. It was exciting! A president and his entourage in the springtime of his hopes.

I nudged my companion, who was fascinated by a water bird out of its realm. "Hey!It's the president!" "No, no, my dear. I'm sure it's a ring-billed gull." I grabbed his arm and pointed at the procession, and he gathered his wits to watch with me. The day's excitement was over except for the bright young thing who jogged up to ask, "Was that who I thought it was?" "No, no, my dear," I answered. "It was a ring-billed gull."

With the summer heat, canal traffic dwindles. Fewer joggers and no celebrities -- all off at the beach or in Maine. Still, a few die-hard joggers pass in the shimmering heat, their features contorted in the jogger's stare, clothing saturated, muscles rippling. Such character. And lots of birds -- all kinds of ducks and geese, gulls, terns, coots -- and wildlife. Nature pure enough to grab the most desensitized of us. I tear myself away from nature in July to watch in horror as a sophisticated lady pedals her bike into the canal. The bird-watcher misses it, but I allow him to help her out and offer consolation. No real harm, just mud and embarrassment.

With the autumn weather, the crowds return, their suntans and bright clothing mingling with the foliage. The bird-watcher glories in a southbound ruddy duck. I look for celebrities but settle with pleasure for older couples stepping sprightly and holding hands, parents teaching young children of the delights of nature. One autumn Sunday we hiked six miles to the park in Georgetown where the canal begins. The area is charming with brick walkways, little shops and art gallerys, gardens and handsomely designed buildings that complement the canal. Still, among the glamorous shops and apartments (with names from the past like the Blacksmith Shop, the Grist Mill, the Glue Factory), the canal seemed like an ancient relative being used for mercenary purposes. I prefer the log section houses placed at intervals along the path.

With winter's first hard freeze, skaters appear. The trees are bare and many of the birds are gone. It's still a pleasant place to hike on unseasonably warm days. There are fewer bikes, more walking room. The sycamores lift their graceful white branches, contrasting with the black gnarled ones of its neighbors. At times it's almost too warm, and then a dash of cold wind cuts right through the jacket. A surprising number of birds do not fly south; the book has to be checked to be certain an American golden-eye is really on our canal.

With the first warm weekend of spring, the canal comes to life in all its parts. Even early in the day a people-watcher has a busy time of it. Everyone, it seems, has come out. On our next outing we seek a more remote section and are surprised by an unusual number of policemen in the parking lot. At first we think a dangerous criminal must be lurking among the sweat-suited populace. Then we spot the limousines, and a sense of deja vu sets in. Although President Carter has fallen with the autumn leaves, we recognize the routine. This is preparation for a leader. A politician cometh. This time it is not a president, but a vice president. The scenario is the same: lots of policemen and motorcycles, big shiny limos, Secret Service all around (dressed like Mr. Such, in shorts), the celebrity pretending to be unaware of the surrounding furor. Only his lady is missing. We watch with interest but soon are distracted by a Canada goose. Are we becoming jaded?