Waterfowl watches around the Chesapeake Bay are training telescopes on the marshes and backwaters with hope of adding another chapter to the saga of T002, a female whistling swan.

T002 didn't always have such a dull name. Once she was the flashy C028. she wore that number on a plastic neck band after she was trapped on the Rhode River near Galesville, Md., in the winter of 1970.

Dr. Bill Sladen was behind that banding exercise eight years ago. And he was along when C028 was sighted next in the summer of 1970.

This time Sladen was aboard a light airplane 40 miles from the Prudhoe Bay oil fields on the North Slope of Alaska.

It was an exciting moment, because it marked the first time Sladen could confirm that flocks of whistling swans that winter in the Chesapeake Bay are largely Alaskan birds. The swans make the long transcontinental flight twice a year, once in the fall and again each spring as they head for their nesting grounds in the tundra.

Chesapeake swan watchers are looking for T002 because she has the most extensive flight history of any of Sladen's banded birds.

She was spotted several times with her mate, T001, between Alaska and the Chesapeake during 1971-75. She got her new number when the old one wore off. Then T001 was found dead in 1975 near Centreville, Md.

Last year no one saw T002 in Alaska or on the Chesapeake, and Sladen and others wondered if she had met the fate of her mate.

Happy news came in March from Jean and Louis Frank of Gettysbury, Pa. T002 had set down for a few hours on a pond near their home, then continued on her way north.

She had with her a new mate and one fresh yearling offspring, the Franks reported.

The Gettysbury sighting brought the confirmed mileage total for T00i to 60,000 miles over eight years, not counting day trips for groceries.

This kind of information, and plenty more about the nesting and migrating habits of the majestic white whistler swans, is relatively new to the scientific community.

It comes largely because of the banding, radio-tracking and sighting work of Sladen, a medical doctor, a professor of public health at Johns Hopkins and a swan freak of the first order.

He is swan coordinator for the International Waterfowl Research Bureau, a 30-nation organization. He recently returned from Moscow, where he delivered a pair of trumpet swans that he escorted over on an Aeroflot flight. The swans traveled with him in the passenger section.

There is an inevitable question of why anyone cares enough about whistling swans to go around banding them with individual numbers and tracking them across the land.

This question would not occur to anyone who had spent a morning or evening in an Eastern Shore field watching flights of the huge birds zoom overhead.

Swans resemble Canada geese in their flight patterns, only they are about twice as big, weighing up to 20 pounds, twice as visible because they are snow white, and they generally fly about half as high because they are not afraid of hunters.

They also make a remarkable, high-pitched howling sound when they fly and when they rest in the marshes. It is an eerie warble-not a whistle.

Add these factors, multiply by 25,000 to 35,000 birds, and one has a rather memorable spectacle.

In an article on whistlers in the July 1975 National Geographic, Sladen wrote:

"Some of my friends have puzzled over my giving up a medical career for studies in conservation and environmental health.

"But, I respond, wouldn't they perhaps trade whatever they are doing to witness the spectacle of 300,000 Adelie penguins in Antarctica, to round up thousands of pink-footed geese in Iceland, to sit among harems of fur seals on the Pribilof Islands in the Bering Sea, or to take inspiration from the wandering albatross as it soars majestically above the southern oceans?

"All these experience have been mine," Sladen writes, "and they are all unforgettable, yet for me the liftoff of whistling swans from the Chesapeake Bay on spring migration equals or even surpasses, in emotional and scientific impact, those other more exotic adventures."

Whistling swans began arriving in the Chesapeake about four weeks ago. Their stocks are high now, particularly in marshy areas where there is good submerged vegetation growth, their principal diet.

They will remain here until the first breath of spring of which time they will depart in the spectacular fashion Sladen described.

Meantime, they are most easily observed at the Eastern Neck Wildlife Refuge near Rock Hall, Md., or at Blackwater Wildlife Refuge near Cambridge, Md.

They usually raft up off shore with the geese during the day, but at dawn and dusk they often can be seen flyin in great vees to the nesting and feeding grounds, squawking their eerie warbles as they go.

Perhaps T002 is among them.