"Turning. Turning. Moving left. Now banking. Flying away fro us. Right between the two power lines. Now flying toward us."
"Adult Thayer's gull!" declares Rick Blom, a well-known Maryland bird-watcher and gull fancier. The bird, one of the rarest of the 17 gull species seen in Maryland, breeds at Baffin Island and other high Arctic sites.
Two decades of practice enable Mr. Blom to use subtle field marks to separate the species from the swirling mass of thousands of more common ring-billed gulls, herring gulls and great black-backed gulls at Conowingo Dam in northeastern Harford County.
"See how the underwing is almost entirely white?" he says.
Gulls, which seem to be everywhere in metropolitan Baltimore during winter, also are among the most challenging birds to study.
Motivated by that challenge -- and a desire to know more about these highly mobile, unpredictable birds -- a small, growing fraternity of gull-watchers fanned out across the state yesterday.
On the second annual "Gull Day," several dozen men and women positioned themselves at some of the finer -- and smellier -- birding spots in the state: Back River Waste Water Treatment Plant in eastern Baltimore County, Alpha Ridge landfill in Howard County, Millersville landfill near Annapolis, Montgomery County landfill near Laytonsville, and elsewhere.
This year, gull-watchers in Delaware also were recording sightings yesterday, and counters were in the Norfolk, Va., area and on a boat off Virginia Beach, Va.
The Maryland count, supplemented by the Delaware and Virginia data, is the only one of its kind in the country.
The churning water below Conowingo Dam, a smorgasbord of gizzard shad, is a magnet for the birds.
In some winters, gulls come by the tens of thousands to feast on stunned and dying shad that have gone through the dam's turbines.
The birds share the feast with bald eagles, common mergansers and other ducks, great blue herons and black-crowned night herons.
Roughly 36,000 of the 100,000 gulls seen on "Gull Day 1992" were spotted at the dam.
But yesterday, only about 1,500 gulls were feeding at the dam.
"This could be the smallest number of gulls I've ever seen at Conowingo," Mr. Blom says.
He and June Vaughn, a bird instructor employed by Philadelphia Electric Co. at the dam's visitors center, theorize that heavy rains have flushed many of the shad downstream, so the gulls simply may be feeding elsewhere.
But, Mr. Blom says, with double the number of gull-watching sites this year, the statewide count will probably be comparable to last year.
The "best" gull spotted at the dam by yesterday afternoon was a common black-headed gull, which breeds regularly in Europe and in much smaller numbers in Iceland and the Canadian maritime provinces.
A member of the same species -- possibly the same bird -- has been seen periodically at the dam since last month.
Learning the field marks of the different gulls, some of which change plumage four times before reaching adulthood, "is sort of like learning a foreign language," says Claudia Wilds, who has conducted gull-identification seminars for the past decade for the Chevy Chase-based Audubon Naturalist Society.
"It gives you a sense of accomplishment and power," she says.
Ms. Wilds, an associate editor of Birding magazine, also is author the book "Finding Birds in the National Capital Area." She is working on a field guide to gulls and terns of the world.
Gulls -- scavengers that eat just about anything -- are adapting extremely well to the human world, turning man's dumping grounds into their own fast-food restaurants.
They roost on the water at night and by day they commute to feeding areas.
"The population of gulls has absolutely exploded, primarily as a result of the increase in garbage and sewage," says Mr. Blom, a Bel Air resident and consultant for the popular National Geographic Society's "Field Guide to the Birds of North America."
Remember 1990 sighting?
That explosion has sent bird-watchers scrambling to find rarities, such as the diminutive and beautiful Ross's gull, which has been seen once in the state, at the Back River sewage plant in 1990.
That bird's dalliance with Baltimore's finest sewage attracted some 2,300 people from 16 states eager to add to their "life lists" of birds they've seen.
Most people know the birds as "sea gulls," and they could no more tell them apart than they could fly.
Although gulls frequent coastal areas, they also are at home in cities farther inland, at shopping centers, in farm fields and at school ball fields.
The birds are as skilled at finding cold french fries in a McDonald's parking lot in suburbia as they are at plucking small fish from around the mouth of a gorging humpback whale at sea.
"Gulls have some endearing qualities," Mr. Blom says.
They are tough, enduring, with members of some species living more than 30 years.
They wander great distances -- sometimes far from their species' normal haunts.
They're superb aerialists, soaring and sailing with the wind and sometimes seeming to play for hundreds of feet in up-drafts.
They frequently harass each other over scraps of food.
Their raucous cackling is one of man's best reminders of the seashore.
Some, such as the great black-backed gull, with a wingspan of more than 5 feet, are serious predators. Mr. Blom recalls seeing one kill and eat a common merganser, a rather large duck.
True gull bums
Gene Scarpulla, a city government worker who leads birding excursions in the Atlantic off Ocean City, has become "addicted" to gull-watching in recent years.
Being the first person to find the Ross's gull in Maryland fanned his interest, says Mr. Scarpulla, who also helped organize "Gull Day."
"When Rick [Blom] first told me he would go to Conowingo in January and spend all day looking at 30,000 gulls, I said, 'Who in their right mind would want to do that?' "
"There are people as foolish as me doing this all over Maryland," Mr. Blom says, standing in the soft mud of the Cecil County
landfill near North East yesterday.
He took a brief side trip to the landfill to count about 7,500 gulls, including two lesser black-backed gulls, feeding there.
"There are so many things that can turn up in the wrong place," says Mary Gustafson, a biologist and Laurel resident, who teaches at Howard Community College.
She calls herself a "true gull bum."
But the gulls' population boom has caused some serious problems for wildlife managers and airport operators.
In Massachusetts, the most aggressive species are pushing endangered roseate terns from their nesting grounds. Biologists have responded by poisoning thousands of gulls.
At Long Island's Kennedy International Airport, 15,000 gulls were shot last year in an effort to prevent the birds from causing airplane crashes.
Herring gulls have colonized in Maryland since the 1950s and are thought to have pushed all the laughing gulls from their nesting grounds, said David Brinker, a state biologist who studies Maryland's gulls, terns and other birds that nest in colonies.
But no conflicts in Maryland warrant government-sanctioned shooting or poisoning of gulls, he adds.
"We want to look at gull populations over a long period of time," says Mr. Blom, the veteran gull-watcher.
Besides, he says, the prospect of spotting more rarities will keep gull-watchers tramping around landfills, sewage plants and other hot spots."
There's always hope of seeing an ivory gull or mew gull, says Mr. Blom, referring respectively to Arctic- and West Coast-oriented species that have appeared occasionally in nearby states in recent years.
"I'm still learning something every time I go out."