As Mayor of Roosevelt Island, Lee Cottrell spreads a half pound of birdseed five days a week, pops paper bags to scatter the crows, slips carrots into raccoon lairs, keeps a lookout for the albino pigeon, broods over the decline of the rabbit population, (she suspects the red fox is involved), chews out teen-agers she happens to catch messing with the Comfort Station, hails fellow hikers, and whenever possible, proclaims the glory of the day.

Mayor of Roosevelt Island is not an elective office, but an honorary title bestowed by U.S. Park Service rangers and maintenance crews on Cottrell, a robust 75-year-old widow who has visited the island nearly every day for 15 years.

"This is my home and my life," Cottrell said a few days ago as she crossed the footbridge that joins Virginia with the island, an 88-acre preserve on which rests a memorial to President Theodore Roosevelt and a commuter bridge named after the great conservationist. "You know I'd build a damn tree house here if I could."

Cottrell, who grew up on the West Coast and ran a beauty parlor before her husband was killed in World War II, could pass for a woman in her late 50s. She clambers up hills and over logs like a goat. She has thick strong hands that can pry open the English walnuts that grow on the island (thus making them accessible to birds). Her ears are large, her eyes alert, and she keeps her gray hair short.

Cottrell rises every weekday morning at 4:30. She has a son and a grandson but lives alone with Tweetie II, the blue parakeet who has the run of her efficiency in Northwest Washington and whose forerunner, Tweetie I, is buried under a tree off Roosevelt Island's Upland Trail. After her orange juice, she climbs into her brown Ford and heads for the island, which she first visited in the 1940s when she took a ferry boat across the river.

Since 1967, when the Roosevelt Memorial was dedicated, Cottrell has tried to stop by every day, unless its raining.

She likes all seasons equally, and knows the pleasures of each, such as the bobcat she and a ranger spotted one winter; the Canada geese whose coming and going mark the equinoxes. She knows where to find the Kentucky coffee bean trees and the ash trees that beavers have logged. While she once gave tours for the Park Service, no one ever paid her to weed the brush, pick up after the litterbugs, or rescue the trapped possum from the garbage can.

Roosevelt Island is an improbable sanctuary, located under the path of National Airport's jet flights, and offering not-so-bucolic views of Rosslyn and the District. But all the same, on a brisk March morning, the air was rife with hints of spring, on the verge of some old and still entirely miraculous renewal. The spice bushes were blooming, willows down in the swamp wore a cloud of greenish-yellow buds, and a pair of mallard ducks drifted on a pond.

"I've gotten so I don't hear the jets anymore," said Cottrell, strolling along Wood Trail, through the chilly early morning air and the cross-hatched shadows cast by oak and maple boughs. She was dressed in a parka, jeans and crepe-soled boots, which she buys three pairs at a time and wears out every six months.

Cottrell paused at selected spots to fling handfuls of seed from a plastic bag cradled under her arm. At each stop all manner of birds fluttered out of the vine thickets and fell to pecking up the seed. There were jays, nuthatches, crows, grackles, chickadees, and the bracing red pointillism of cardinals in the gray woods, as brilliant a sight as last year's bone-white ash leaves still clinging on the branch.

"I came over one day on a full stomach and the birds followed me around," Cottrell said. "I couldn't stand it. I went back to get some food."

Before long, Cottrell's birdfood bag was empty, but she continued to tour the island. She encountered another 75-year-old visitor, Mary Craig, whom she called Miss Craig.

"You used to be with HEW," the Mayor said.

"You used to be with Public Health," Miss Craig said.

"Oh no, I never worked for the government," Cottrell said amiably.

"Must be somebody else."

The pair praised the day and the newly bloomed white-flowered toothwort. Taking leave, Cottrell slapped Craig on the arm with the empty birdfood bag and said, "Just call me Lee."

In three hours, Cottrell circled the island twice. She sat on a log by a small sand beach that looked out on the Kennedy Center, where she said she's never been, although she has lived here 37 years. She skirted the swamp, where the red-winged blackbirds displayed their scarlet chevroned wings and the May apple plants were lifting their umbrella-like leaves; toured under the bridge where she once found a couple of junkies shooting up; passed by the hole in the chain-link fence where a homeless man sometimes sleeps; and sauntered through the presidential memorial where a dead mouse lay on the trail with its throat gashed open.

As well as she knows the island, she never found the den where the red rabbit-eating fox is supposed to live. But nature, after all, is a mystery. At the end of her rounds, she looked gladly out where the Little River channel of the Potomac surged gently over rocks.

"I could sit by these rocks and dream for hours," she said. "When I've been out on the island, I sleep like a log at night. In the morning I wake up Tweetie and go out again. When I die I want to be cremated and I've told my son and my dearest friends to scatter my ashes on the island. My son is so naive. He said, 'They won't allow it, you can't just scatter ashes on the island.' I said, 'Who in hell is gonna know?' "