WYE ISLAND - There is nothing silent about the mute swan standing guard on the sandy spit of land across from his nesting mate.
Hissing and puffing himself up, the huge white bird makes for biologist Larry Hindman's small boat at ramming speed. But the menacing swan is no match for the biologist armed with a squirt bottle filled with cooking oil. Within minutes, the embryos inside the nest's six eggs will be suffocating.
Hindman is part of a state and federal effort to reduce the population of the beautiful, yet destructive, bird before it can do any more harm to its Chesapeake Bay habitat. The two-part plan calls for smothering 1,500 eggs now and killing as many as 1,000 adult birds later this year.
Congress removed the birds from a list of protected species in December and the U.S. Fish and Wildlife Service did likewise last month. That opened the door for Maryland to begin its program.
But animal-rights activists are challenging the federal wildlife agency's authority to lift the swans' protection and Maryland's right to kill them.
"The [Maryland] Department of Natural Resources has not been able to prove that the swans are causing a problem," says Michael Markarian, executive vice president of the Humane Society of the United States. "For whatever reason, the DNR is hell-bent on killing these swans."
Opponents plan to file for a preliminary injunction this week to prevent Maryland from killing the adult birds pending the outcome of a lawsuit against the federal government.
So for now, egg addling is the biologists' only tool.
Hindman beaches his boat along a secluded stretch of the Wye River in Talbot County and tromps in shin-deep mud toward his objective: a huge basket of reeds and corn stalks holding a clutch of seafoam-green eggs.
The female swan stretches her long neck to view the approaching man, then waddles into the cove, a V-shaped wake marking her retreat.
With four or five quick squirts, Hindman coats each egg with a thin sheen of oil, then places it back in the nest. Within hours, whatever life was growing inside the shell will be snuffed out.
"It's very effective, more effective than just shaking them," he says as he works on an egg, about the size of a man's fist. "These won't hatch."
Not far off shore, the agitated swans beat their 4-foot wings against the water, creating a sound like war drums.
"They've been known to attack people," says Hindman dryly as he finishes up.
Today's mute swan population is descended from a handful of birds imported from Europe in the 1950s by a wealthy Eastern Shore landowner to decorate his estate. The birds took to their new surroundings and bred throughout the bay.
An aerial survey in January put the Maryland population at about 3,500 birds, but several prime nesting sites near military bases could not be viewed because of security issues.
The swans take their toll on the bay. Each adult can eat up to 8 pounds of underwater grasses daily - destroying critical vegetation that filters bay water and controls erosion. The birds also squeeze out native waterfowl, such as least terns, black ducks and tundra swans, bay experts say.
"It's hard for people to believe that a fairy book creature could be a problem for the Chesapeake Bay," says Jonathan McKnight, the head of the state's invasive species program. "None of us hold the swans responsible for this. The swans are doing what swans do, and they are doing it well.
"It's just another case where man has done something dumb, something inadvertent, and it's gotten out of whack."
Addling is designed to fool the birds so that they continue to sit on the nest and don't attempt to breed again. This year, state biologists and volunteers will reach about 250 nests, or 70 percent of the nests in Maryland's portion of the bay.
"It's a more humane way to deal with wildlife," says Markarian, in one of his few agreements with DNR. "If done properly ... it certainly is preferable to shooting or rounding them up and gassing them."
However, wildlife managers say, it's not enough. Mute swans reach breeding age at 3 and live to be 20 to 25 years old. Each year, the female lays an average of six eggs. About half of the baby birds make it to adulthood, and most of those birds live to old age.
The prolific breeding has allowed the population to increase by more than 1,000 percent since 1986, according to state figures.
"Addling is a stop-gap measure. We're just putting our finger in the dike," says Hindman. "This is a bird that has the ability to increase its population almost exponentially. To reduce the population, you need a combination of addling eggs and shooting the adults."
Last year, Maryland and eight other East Coast states with mute swans put their addling programs on hold during litigation with animal rights groups.
"Everybody lost when we lost a year," says McKnight. "It allowed an entire generation of birds to get that much closer to breeding age."
Opponents, led by the Humane Society and the Fund for Animals, believe that despite the congressional action, the swans are protected under international migratory treaties.
"These aren't migratory birds. They're here all year round, feeding on grasses, getting ready to reproduce," Hindman argues.
Other conservation groups, including the National Audubon Society, the Nature Conservancy and the American Bird Conservancy, have sided with DNR, believing that the mute swans are not covered under the treaties because they were introduced to the bay by man.
"This has split the environmental community right down the middle," Markarian acknowledges. "There are groups that, unfortunately, like certain birds and don't like other birds. Some of it is driven by birdwatchers who want to see certain species. It's really based on aesthetics."
As occasional raindrops pockmark the silky surface of the Wye River, Hindman marks the GPS coordinates in a ledger and on a map and moves on. His work this month and next is being duplicated around the bay-on Anne Arundel's South River, in the creeks near Rock Hall and in marshes around the Key Bridge and Havre de Grace.
Hindman prowls the bay, map in hand, trying to beat the biological clock.
"We've only got this small window," he says, gunning the engine and moving upstream. "Once they get out, there's nothing we can do."