Naturalists Cry Waterfowl Over Bird

They are the subjects of myth and poetry, the stars of operas and ballets. Silent and serene, swans are the embodiment of elegance, gliding with nary a pure-white feather out of place. Thought to mate for life, swans are all but synonymous with romance. In the spring, trailed by smoke-gray cygnets, they are widely admired as devoted parents.

But naturalists who study the ecology of New England’s ponds and saltwater marshes say that particularly in the case of the mute swan, the most common variety, this idealized image is nowhere close to correct. They are not only nasty, these experts say, but they are also territorial and destructive. Worse, they are proliferating at disturbing rates.

“They are an exotic species. They are not native to this continent--and their potential to do harm is very, very great,” said Jim Cardoza of the Massachusetts Division of Fisheries and Game.

Mute swans are aggressive predators who drive off smaller birds, then take over their territory, ornithologists say. They upset pond and marsh ecology by swallowing four to eight pounds of foliage per day--roots and all. Then they further foul their habitat by depositing their droppings. Swans have been known to attack dogs and humans--and with 7-foot wingspans and quills the diameter of a pencil, their wings can do damage to both.

None of this would be so worrisome if the region’s mute swan population was not undergoing a mini-explosion. In the Atlantic Flyway--stretching from Maryland to Maine, from the Atlantic Ocean to Michigan’s eastern border--the mute swan population has increased by 93% in the last 10 years. In Massachusetts alone, the bird’s numbers have grown by 57% in the same period.

“Imagine if this were some kind of burrowing rodent,” Cardoza said. “Imagine the outcry you’d hear to get rid of them.”

But if mute swans came to this country because they were easy on the eyes, their beauty continues to protect them. Wealthy Long Islanders first imported the birds from Western Europe in the mid-19th century so the man-made ponds on their lavish estates would look like true castle moats, swans and all.

From there the big birds were released to city ponds. In Boston, the mute swan assumed a kind of totem stature. Mute swans swim on the pond at the Boston Public Garden, right alongside the popular swan boats that are tourist magnets.

Towns come to feel proprietary about “their” mute swans. At the Massachusetts Audubon Society, naturalist Linda Cocca said she receives more calls about mute swans than any other avian species.

“People call, worried that the female is sitting on her nest for too long, or worried that she’s not getting enough to eat,” Cocca said. “Nobody calls worried about a sparrow.”

Mute swan protectiveness took on near-vigilante proportions recently in Vermont, said James Bressor of the state’s Agency of Natural Resources. At Arrowhead Mountain Lake in the northern part of the state, a group of mute swans happily--if destructively--set up housekeeping. Well aware of the bird’s population growth in Massachusetts, Rhode Island and elsewhere, state wildlife biologists decided it was time to “stop ‘em before they multiplied,” Bressor said. But when they announced plans to exterminate the alien avians, residents rose up in protest.

Eventually, a wildlife park in Texas rescued the birds in question. In the meantime, however, the birds had apparently told their friends about the great conditions at Arrowhead Mountain Lake. When a new swan colony showed up this spring, state wildlife specialists shot the birds with no announcement beforehand.

“Nobody up here liked doing it,” Bressor said. “But we had just heard too many stories from other states where they didn’t nip the problem in the bud.”

Bressor added that none of the same protesters seemed to object when hunters took aim at Vermont’s deer population.

In Rhode Island, environmental officials have taken to addling--or shaking--the nests of mute swans to prevent their eggs from maturing. But this practice is cumbersome, naturalists say, because mute swans lay from four to eight eggs in large, mound-like nests usually located in reedy, marshy zones. Their breeding capability extends for much of their lives, often from 25 to 30 years.

Addling eggs is both labor-intensive and risky because nesting mute swans are even meaner than usual. Maternal fierceness is not the only hazard, either. A pregnant volunteer in Rhode Island said she was addling mute swan nests when a bird lover marched up and asked how she’d feel if someone did that to her.

“People don’t want any harm to come to them because they are so beautiful, because--they think--they are so much like us,” said Massachusetts Audubon Society ornithologist Simon Perkins. A steady diet of stories like “The Ugly Duckling” and ballets like “Swan Lake” has given these birds near mythic status, Perkins said.

“Just because we find them elegant, we take it beyond the bounds,” Perkins said. “We invest them with some special sense of eminence.”

One possible way to reduce the mute swan population might be to harvest them. Gourmets munch on ostrich, after all, and quail is also a sought-after delicacy. Much like the turkey, swans are large--often weighing more than 25 pounds.

But if swan steak showed up on diners’ menus, Perkins said, “they’d be horrified. No one would order swans.”

Some of that sacrosanct quality might be forgotten, he conceded, if the public knew the truth about mute swans. Not only are they vicious, alien predators, they’re not even all that monogamous.

Mute swans do divorce, Perkins said, and they do cheat. Often, if a female dies, Perkins said, her mate takes up with a new lady before the feathers are even cold.

Still, the mute swan remains ennobled by good looks and powerful press agentry. Even in the bird world, Perkins said, “image is everything.”