Erica Wasylk and her cockateel, Cappy, used to sit on the prayer bench at church together. She prayed and he just hung around. But then, says Wasylk, "I had to quit taking him when he learned to wolf whistle."

Wasylk, who is crippled by multiple sclerosis, tells this story from her wheelchair at the Washington Home on Upton Street, the private, nonprofit, long-term care facility where she lives.

Cappy has added a sparkle to her life that otherwise might be lacking. "I've fed him since he was 6 weeks old," she says proudly. Without Cappy, the Washington Home "would be dull for me."

Cappy is not the only perky little creature at the home. There are also six finches and two canaries for the 178 chronically ill residents.

All the animals were provided by People Animals Love Inc. (PAL), a nonprofit volunteer organization that places pets as companions in institutions and in the homes of elderly people living alone.

Margaret Pully, activities director at the Washington Home, said the birds have been stimulating to some of the unhappy and withdrawn patients at the institution--just the effect that PAL officials were hoping the animals would have.

"Pet therapy," introduced recently in several District institutions, is gaining credibility and popularity nationwide. Advocates and researchers agree that animals have potential as a therapeutic tool, although they say more hard data are needed on human-animal interaction.

"People that are institutionalized--whether in a nursing home, hospital, or prison--tend to lose the ability to do things for themselves," said Dr. Earle Strimple, PAL president and a veterinarian at MacArthur Animal Hospital at 4832 MacArthur Blvd. NW. "We all have the need for touch, for companionship and for something to look after."

PAL was created in January 1982 under the auspices of the St. Francis Center, a nondenominational counseling service on death and dying at 1768 Church St. NW.

The Washington Humane Society provides dogs and cats for the program; PAL, which gets money from private contributions and a grant, buys fish, birds and rabbits from a Rockville pet store. It also provides food, supplies and volunteers to help recipients care for their animals.

Volunteers, currently 15 of them, are trained for two days at the St. Francis Center "both in animal care and in the psychosocial needs of the recipients," said psychotherapist Judith Pollatsek, PAL's volunteer instructor.

PAL has placed animals in a number of local institutions: The Washington Home, Lorton Prison and the Health Care Institute, a private, nonprofit nursing home at 1310 Southern Ave. SE.

It also has installed aviaries at three long-term care facilities in the District: the Washington Center for Aging Services at 22601 18th St. NE.; the Wisconsin Avenue Nursing Home in Northwest; and the Little Sisters of the Poor at 4200 Harewood Rd. NE, which received a 20-gallon fish tank, too.

People in the institutions say the animals are popular additions.

Ernestine Lawrence, 62, one of 80 residents at the Health Care Institute, cuddles a sleek calico cat named Sappo in her lap.

"Sappo is my best friend," she says. "When Sappo comes around . . . it's uplifting."

Another resident, Richard Anderson, 76, was depressed recently during his recovery from a bladder operation, staff members said, but he brightened at the mention of "Pretty Bird," a yellow cockateel kept in the lounge down the hall from Anderson's room. "I love that bird," he said. "I get up early to get my coffee and stop by to talk to him."

Inmates at Lorton also like having pets. The prison received a handful of rabbits, fish and birds from PAL last August. Since then, the animal population has grown steadily; 32 inmates have enrolled in the pet therapy program, and dozens more are on the waiting list.

In addition to PAL's programs, three units on the grounds of St. Elizabeths Hospital have their own versions of "pet therapy."

A pet shop owner takes animals, including rabbits and hamsters, to two geriatric units at the hospital every Tuesday evening. Volunteers from the Arlington Animal Welfare League bring kittens and puppies to one unit of 50 residents once a month. The animals have been greeted enthusiastically at both units, administrators say.

The Last Renaissance, a long-term drug rehabilitation program for 29 adult residents, is the only part of St. Elizabeths where animals are kept. The director and house psychiatrist, Dr. Ester Ordonez, recalled that the practice began 12 years ago during the winter when patients took in a lost puppy. They named the white mongrel Sugar and pitched in to pay for food and veterinary care. Two stray cats soon followed.

"Taking care of a living thing gives them a sense of responsibility and of being able to help . . . ; before, they were only concerned about themselves and where their next fix would come from," Ordonez said.

Last Renaissance residents say the animals help them adjust to the facility by making it more homey and less lonely.

"I was at the point where I couldn't take care of myself on the street . . . " a Southeast man, 35, said. "Having to care for the animals helped put me back in touch."