Caren Pauley was sitting with her husband at a fashionable Georgetown restaurant along the C&O Canal amid the flowers and soothing ambiance of an evening out when she looked out the window and saw them - eight or 10 of them - creeping along the towpath.

"It was a whole school of them," said Pauley, a Georgetown resident and advisory neighborhood commissioner. "They were so big at first I thought they were cats."

At a popular sidewalk cafe on Capitol Hill, a place alive with quiet chatter and the flicker of table candles, a waiter pretended not to notice the sleek shadows scurrying back and forth nearby. Nested under the sidewalk less than 10 feet away, some four-footed uninvited guests were sniffing around for gourmet tidbits.

Rats.

Like social climbing predators following a trail of canapes, the rats of Washington are moving to Georgetown and Capitol Hill.

Displaced by downtown construction and neighborhood cleanups elsewhere, they are strolling with new openness among the fern-hung bayfronts and English basements of Washington's highest priced real estate.

Sometimes they may even take the subway.

An assistant manager of a men's store in Northwest Washington recalls seeing "two ordinary, everyday rats" come up the escalator "just like people" at the Farragut North Station at Connecticut Avenue and L Street NW.

Other rats have been seen near the still-unopened Zoological Park station on upper Connecticut Avenue near Woodley Road and Calvert Street NW, at the Judiciary Square station at 4th and F streets NW, and at Metro Center at 12th and G streets NW.

At times, it seems, they're everywhere.

When a staff member for Sen. Jake Garn (R-Utah) had trouble transferring calls on his Dirksen Senate Office Building phone - even after it was replaced - an investigation showed the phone's wires had been gnawed away by little teeth.

There is nothing really new, of course, about rats in Washington. They flourish despite 50 tons of poisoned bait spread around by the city each year.

What is new is their sudden visibility in Georgetown and Capitol Hills, where native rat populations have traditionally stayed more or less in the closet.

City officials last month logged about 120 rat complaints from Georgetown and Capitol Hill - more than three times the number reported for the same period last year.

With more complaints than usual coming in from Georgetown recently - 35 in the last two weeks - city workers have begun baiting along the Georgetown waterfront, the scene of warehouse demolition and renovation.

"It's the construction, the litter from snack and fast-food restaurants and the food that people dump on the street," said Pauley.

Its not that the city can't kill rats effectively. When the "War on Rats" program, which costs about $1 million annually, started in 1968, one out of every four Washington homes was rat infested. Today, officials said, the figures show one out of every 25.

John Gallagher, of the U.S. Department of Health, Education and Welfare's Center for Disease Control, said, "without reservation, the D.C. program is among the best in the country."

But while the program has proven effective in targeted areas, it is less effective against rats on the move.

City officials noted the shifting rat population as early as 1970, two years after the highly-touted "War on Rats" program began in the downtown Model Cities area, one of the most heavily infested even today. Eleven years ago in the area bounded by Florida Avenue on the north, 16th Street NW on the west, Massachusetts Avenue to the south and Maryland Avenue to the east, every other house had rats.

By 1970, the rat rate in the Model Cities area dropped from rats in every other house to rats in every sixth. But Capitol Hill and far Northeast - areas not in the program - began seeing more rats.

From rats in every fourth house in those areas, the rate jumped to rats in every third. Program officials believed the rats were migrating out of the Model Cities area in search of food and shelter.

Today rats are not only more prevalent in some areas but but more visible.

Ordinarily, rats are seldom seen except at night, unless something is radically wrong. In the 13th century a population boom among black rats in Europe triggered the Black Plague. $ Millions died from plague bacilli spread by fleas the rats carried.

The black rat, however, was all but wiped out in Western Europe by the ferocious Norway rat, an uninvited immigrant who jumped ship from Scandanavia in the 18th century.

Washington's rats are Norway rats, although time and circumstance has improved the breed. Brown, beady-eyed and furry, they are supposed to grow to a maximun adult size of 18 inches nose-to-tail and top weight of about one pound.

"But when you hear complaints about them, they're the size of cats and dogs," said James Murphy, head of the "War on Rats" program.

And rat bites are no laughing matter.

Four rat bites have been reported in the city so far this year, and officials say the total would be far higher if reporting procedures were better and if people took time to report bites.

Most of those bitten were infants.

"I've seen a baby bitten 22 times about the face and lips," said Harold Laster of the "War on Rats" program. "I know of peole who sleep with lights on, sleeping in shifts while other family members stay up with sticks and bats to keep baby brothers and sisters from being bitten," Laster said. "And it's still happening today."

"Usually, it's the baby that is bitten by rats," Anderson said. "The baby is put to bed with a bottle, falls asleep with milk on its fingers and lips and the rat climbs in the bed looking for food. Rats don't see well. When they smell food, they start to nibble."

Elbert Ramsey, a pest controller, said rats spend most of their time looking for food. "Get rid of the food source and you can get rid of rats," he said.

The "War on Rats" program is based on a three-step method. The first, and most important step is removing any source of food so that rats will eat the poison bait - Rozol or Warfarin, anticoagulants that cause rats to bleed to death internally.

The next step, Ramsey said, is to plant the bait inside rat burrows, making it easy for them to find it.

The last step is to remove the trash, weeds and debris around homes, vacant lots and alleys - good nesting sites for rats.

There is a certain irony in the migration of rats to Georgetown, which tacitly fulfills a threat made by the late city councilman Julius Hobson during his militant days in the late 1960s.

When Congress appeared to be balking at approving money for the rat program, Hobson collected a cage of truly enormous rats in the alleys of the District's Shaw area. Then he called a news conference to announce plans to turn the rats loose in Georgetown to help people there learn to understand the problem.

Hobson drove around with cages of rats on his car roof for a few weeks while horrified congressmen called each other in alarm. He got his money.

"Those people moving into newly renovated areas are going to have to deal with the rat problem just like the people they replaced," Ramsey said.

"But maybe they can have some effect on cleaning up the neighborhoods and reducing the rat's favorite environment.

"The rat problem is a people problem," Ramsey said. "Our problem is not how to kill them, but how to keep them from coming back." CAPTION: Illustration, Norway rat (Rattus norvegicus) - By Susan Davis for The Washington Post