Grethe Hall perches on the edge of a stool and peers through her bathroom window. She waits with excited anticipation for the birds to visit the backyard feeder station that she’s built for them.

Nearby rests her bird diary and her Peterson’s guide to birds. Outside, the chickadees flutter down and land on the roof of the wooden shelter. They peck at the bark of some pieces of white pine before moving on to the peanuts, their favorite treat. On the ground, a frustrated squirrel paces, waiting to snatch up any crumbs the birds may drop.

“I do this for them because they literally saved my life,” she says as she watches the birds. “They help make each day worth living, and there was a time in my life when I never thought I would be able to say that.”

Up until 1978, Hall, 58, was a healthy adult operating a successful business from her Bangor home. In January of that year, however, she was hospitalized with a fever of unknown origin that spiked to 105 degrees. The medication she was given to control the fever sent her into a deep depression. She lost weight and interest in her business.

By 1981, Hall’s depression had become so severe, she was hospitalized. She spent the next five years in four different institutions in northern New England. When she returned home, Hall realized she needed something to keep her from focusing on her illness.

The former businesswoman kept busy renovating her Wood Street home, using the skills she had learned in woodworking classes while institutionalized. She began sewing and knitting for needy children, but it was not enough to keep the depression at bay.

“I needed something badly to draw me outside of myself emotionally,” she explains. “I had always enjoyed watching the birds. So one winter day a couple of years ago, after a storm had knocked down a lot of small branches, I gathered them up and built a shelter. It was kind of like a stovepipe resting on the ground. But it was 6 feet tall and the birds loved it.”

So did the squirrels. And last year, Hall realized she would need the wood on the bird stand for fuel for the upcoming winter.

“I see a squirrel and all I can think of is a big rat,” she declares. “That’s all they are to me. They scare away the birds and hog all the food.”

Like many bird lovers before her, Hall set herself the challenge of defeating the squirrels. A confessed scrounger, she gathered pieces of an old telephone pole, plastic sewer pipe, used wood from a neighbor’s remodeling project, a cast-off sled, an air mattress.

At yard sales, she bought hanging wire baskets, bowls and discarded pieces of plastic sheeting.

“On Dec. 18 [1996], it was 55 degrees and I went out in my shirtsleeves and built the station,” she recalls. “I had it all put together. Then I put some wooden pieces on top that were too heavy, and the whole, entire thing collapsed. I was pretty devastated.”

The next day, however, in much colder weather, Hall got back to work and finished her feeding station. This time she anchored it to a steel pole she had found on one of her long daily walks. “It hasn’t budged since,” she brags.

The station, which looks like an elaborate lean-to, is approximately 6 feet long, 4 feet wide and 10 feet high. Each of the four telephone-pole pieces that serve as supports are wrapped in plastic sheeting. The front of the station, which faces Hall’s bathroom window, is open. The other three “walls” are made of recycled wood, as is the roof.

Attached to the lower portion of each wall is some item made of plastic — the sled, the air mattress, an old shower curtain. The plastic is her secret weapon against the squirrels. Their claws can’t penetrate it, so they slide to the ground, unable to disturb the birds feeding above.

Wire baskets, the kind usually seen in kitchen windows, hang from the ceiling. Bowls brimming with sunflower seeds and peanuts are nestled inside them. Hall offers her birds several different landing sites, including a 5-gallon water jug hung upside down, as well as traditional bird feeders.

Since beginning her bird watch, Hall has recorded some unusual sightings at her city home, including a Cooper’s hawk usually found in woodlands and river groves.

“One morning I was watching my chickadees feeding when suddenly a Cooper’s hawk swooped down and snatched up one of them,” she says. “He landed on a stump by the side of my driveway. From my side-door window I could see him.

“I stared at him and he stared at me for the longest time. Then, very slowly, he plucked each feather from the poor chickadee. It just broke my heart. I couldn’t bear to watch him eat it.”

Now Hall is content to feed her “regulars” — six chickadees that nest nearby and come to her station each morning. This summer, however, she plans to put a small pond or birdbath in the bottom of the station.

“I give them raisins, cereal, thistle, peanut butter crackers, sunflower seeds, suet, a bird-seed mixture, oranges and apples,” she says. “This year I haven’t had as many different birds as I had last year. I guess it’s because it hasn’t been as hard a winter, and we’ve had so little snow.”

Hall believes it is the least she can do for the creatures who’ve saved her life.