ALIEN SPECIES CAUSE LOCAL ANGUISH

Many changes to our environment are obvious. No one can miss seeing what a new shopping mall or a housing development displaces in the way of wild space. Most negative aspects of environmental change, however, are much more subtle.

Take loosestrife, for instance. It’s a beautiful addition to any yard or garden, but wind disperses its seeds across miles of fields, smothering and supplanting our native vegetation. Similarly, stately phragmites have usurped the indigenous cattails, causing the decline of marsh-breeding species like least bittern, common moorhen and other water birds that used to inhabit cattail marshes. There are many other plants, not showy at all and not native to North America, that also thrive where land is disturbed and then spread out in all directions, choking out native flora.

Unfortunately, mute swans, as handsome, majestic and graceful as they are to behold, are much like the purple loosestrife, the phragmites and other non-native, exotic, plants. Mute swans, native of Europe and Asia but introduced into the United States in New York's Hudson River Valley in the 19th century, "have the potential to do harm in very, very great ways," according to Jim Cardoza of the Massachusetts Division of Fisheries and Game. “They do not belong in North America.”

I know! I know! I can hear your cries of indignation and anguish! I know what many of you are thinking. “But our swans give our ponds real character!” “I love to watch them!” I’ll not argue, for ‘tis all too true. There is little that can match the elegance of a pair of swans parading around a pond, but decorative isn’t enough to cut it — not anymore and not when so many species are declining. So, what’s wrong with swans, anyway?

First off, ornithologists say mute swans are aggressive predators who drive off smaller birds, then take over their territory. 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. They forage by immersing their heads and bills beneath the water, searching through the sediment, and by consuming aquatic vegetation, terrestrial seeds, and grasses on the water’s edge and shore. Occasionally they eat amphibians, fish, mollusks and insects.

Secondly, these swans are known to attack dogs and humans, and being fifty (or a little more) inches in height, weighing 30 pounds, and having wing spans of 8 feet with quills the diameter of a pencil, they can do damage to both. Not only are they nasty, territorial and destructive, they are proliferating at disturbing rates.

The females, who breed once a year, lay up to eight greenish gray eggs in large, mound-like nests built of plants and feathers that are usually located in reedy, marshy zones. Their breeding capability extends for much of their lives, often from 25 to 30 years. 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!"

Some of the mute swans’ sacrosanct quality might be forgotten if everyone knew the truth about them. According to Simon Perkins, naturalist at Mass. Audubon’s headquarters in Lincoln, “Not only are mute swans vicious, alien predators, they're not even all that monogamous; they do divorce and they do cheat. Often, if a female dies, her mate takes up with a new lady before her feathers are even cold.”

Whatever reasoning brought them to this country, mute swans' beauty continues to protect them. Whether it’s those that swim on the pond at the Boston Public Garden, right alongside the popular swan boats that are tourist magnets, or nest on town lakes, everyone seems to feel proprietary about "their" mute swans and worry about them as they go through their courting and nesting cycle.

If you want to worry about and protect birds, put your energies into preserving our area’s bobwhite, whippoorwill, and grassland sparrow populations, as well as our native flora. They may not seem as worthwhile as protecting mute swans, but remember these old adages: “Beauty is in the eye of the beholder.” “Beauty is only skin deep.” “Handsome is as handsome does.” Forget the images of "The Ugly Duckling" and ballets like "Swan Lake" which have given these birds near mythic status and support the wildlife biologists who seek to exterminate these alien avians. Remember, mute swans are alive and doing well in England and Europe, their native lands.