The cat moved silently from her hiding place in a garage, stepping over broken pavement to find a safe spot to watch the quiet Tenleytown alley. She appeared to be posing for a celebrity photograph, her white bib glowing in the dusky setting and her tail wrapped neatly around her.

Cat trapper Sue Nelson had waited an hour for this moment. Speaking softly, Nelson encouraged the cat she had named Chessie to try some tempting white tuna left in a nearby cage.

"Hello there, pretty girl," she purred. "Come on, Chessie."

Chessie contemplated Nelson and the cage and thought better of it all. She turned and walked back through the six-inch square hole cut in the garage door and was gone.

"She is following her intuition," Nelson said. "Cats are like that."

And that ended Nelson's 44th night as a volunteer cat trapper who has assigned herself the task of capturing seven adults cats and 11 kittens who had made their home in the garage behind the 4700 block of Wisconsin Avenue NW.

After an initial wave of success, she has stalked the three remaining adults for the past month.

Nelson said she became involved with the cats because she feels there are too many strays breeding too many unwanted kittens.

She has the adult cats spayed or neutered. She said she would pay the costs herself if the alleged owner of the cats did not.

She extracted promises from those adopting the kittens to do likewise with their new pets.

The owner of the garage where the cats stay, Clarence Schatz, said cats had moved in several years ago and he fed them.

Since meeting Nelson and hearing of her concerns, he said, he has agreed to pay the veterinary costs for four of the cats that are his favorites. Chessie is one of the four.

He said he anticipates the costs to exceed $1,000 because of the boarding times for two of them.

The District government has long recognized the need to have adult animals spayed and neutered and offered a low-cost procedure on a five-day-a-week, walk-in basis. However, as of July 13, city budget cuts have forced the Washington Humane Society, which runs the city's shelter, to reduce the hours to one day a week on an appointment-only basis, said Humane Society director Jean Johnson.

"We are very concerned about the long-range effect of this reduction in service," Johnson said. "The availability of low-cost neutering and spaying is key to some of these animal control problems."

Johnson said volunteers like Nelson are needed to help control the alley-cat population.

She doesn't know how many cats populate the city's back streets or how many volunteers are trying to reduce the population. But she does know they perform an "invaluable" service.

"Usually we pick up the animals or they bring them to us," Johnson said. "They will work with us until the problem is eradicated. We are so short-staffed, there is no way we can sit in the alleys and wait for the cats to come out."

Johnson noted that Nelson was placing the kittens and cats in homes rather than bringing them to the shelter.

"We are concerned that some of these wild kittens will never become completely domesticated and they will be a disappointment to the adopting families," she said. "We have many healthy, round-faced kittens available for adoption at the shelter and we'd love to see them placed."

Nelson said she found homes for the cats because she feared they would be euthanized at the shelter. Johnson agreed that was possible. Schatz said he became an owner of the many cats quite by chance. "A few years ago, some cats just showed up and adopted me," he said. "Sometimes there would be two and sometimes nine. I never thought of them as my cats exactly. I was just trying to help them out."