Mute Swans: A Beautiful Nuisance
January 19, 2012
Certainly no waterfowl are as celebrated in art and literature as swans.
From early childhood, youngsters are told the tale of the ugly duckling, a young bird that is ostracized by the others, until it eventually grows into a beautiful swan.
In Greek mythology, Helen of Troy was conceived by Leda, Queen of Sparta, and Zeus, who came to Leda disguised as a swan.
Often thought of as symbols of love and fidelity, swans figure prominently in several major operas (Lohengrin and Parsifal) and the famous Tchaikovsky ballet, Swan Lake, is among the most performed of all classical ballets.
But, as with any other species of flora or fauna, there is a negative side to swans. In Michigan, mute swans, the largest and most numerous of the swans in the state, have become a nuisance.
In short, there are too many of them. Overly aggressive toward other waterfowl, and often to humans, as well,mute swans, which are not native to Michigan, are crowding out other species of wildlife, doing considerable environmental damage to wetland habitats, and sometimes creating a public safety hazard.
Mute swans can measure up to five feet from end to end, weigh in excess of 30 pounds, and sport a wing span of nearly 10 feet. So named because they make little sound, except for hissing when they're agitated, mute swans contrast sharply with the aptly named trumpeter swans, which, unlike mute swans, are a native species on the threatened list in Michigan.
The Michigan Department of Natural Resources has partnered with other conservation groups for a number of years in an attempt to increase trumpeter swan populations in Michigan. Though the effort is beginning to bear fruit, the DNR said there is evidence that mute swans may be getting in the way.
According to Barbara Avers, the waterfowl and wetlands specialist with the DNR's Wildlife Division, mute swans are not native to North America. Eurasian denizens brought to the United States from Europe in the mid1800s to adorn parks and private estates, mute swans have proliferated. Michigan now boasts the largest mute swan population in the United States; that's a far cry from when a pair of mute swans was first introduced in Charlevoix County in 1919.
The DNR estimates breeding waterfowl numbers based on aerial surveys conducted in spring. The current mute swan population is estimated at around 15,500, roughly three times the number here a decade ago,and expanding at about 10 percent a year. A long lived (close to 20 years) bird that is capable of producing around five cygnets per pair annually, mute swans have few natural enemies.
"Mute swans are aggressive toward both humans and other wildlife," Avers said. "Numerous mute swan attacks on small boaters, canoeists, kayakers, or those on personal watercraft, have been documented, some resulting in human injury. Mute swans will attack people on land who wander too close to their nests or their young. They will drive other waterfowl from suitable habitat, impacting not only ducks and geese, but native swans as well."
Mute swans affect other species, too. The DNR has been monitoring a nesting colony of black terns (a species of concern) on the Upper Peninsula shore of Lake Michigan in Delta County. A pair of mute swans built a nest in the area, destroying valuable habitat and driving away terns. Black tern counts have been depressed since the mute swans moved in.
But population control efforts can pay off; removal of mute swans from the Crow Island State Game Area has resulted in a pair of trumpeters taking up residence and nesting, Avers said.
Mute swans often congregate in large flocks and are capable of inflicting significant damage to aquatic habitat, by feeding heavily on aquatic vegetation that is valuable, as both food and cover, to fish and other species of wildlife. Anglers complain that large flocks of swans virtually wipe out aquatic weed beds in some lakes.
Because of the mute swan's aggression toward native waterfowl, the DNR has long removed mute swans from state game areas, where protecting and enhancing native wildlife is a paramount goal. As the mute swan population has continued to grow, the DNR has recently increased its control efforts, hoping to halt population growth within the next several years and reduce the overall population to 2,000 by 2030.
"If we don't do anything to reduce mute swan populations, we could have 24,000 in five years," explained Avers. "If we allow this to happen, Michigan's wetlands and wildlife would suffer and there would be unacceptable levels of conflict with people."
Numerous conservation groups,including the Michigan Audubon Society, Ducks Unlimited and the Kellogg Biological Station of Michigan State University, are on board with the DNR goals.
The DNR dispatches aggressive swans that cause conflicts with humans and issues permits for private property owners to remove mute swans or their nests or eggs. In the case of swans on commonly held private property, such as a private lake, the DNR has instituted a set of rules to make sure a majority of the landowners are on board before permits are issued.
Permits for the removal of mute swans or their nests and eggs may be issued by the DNR for public health or safety, concerns over threatened or endangered species, and to prevent additional population growth or the establishment of new populations.
Not sure how to tell the difference? Adult mute swans are easily identified. Mute swans have orange bills. The native Michigan species, trumpeter and tundra swans, have black bills. Mute swans also have a knob on the top of their bills, which is absent in the native species.
Because they are visually striking and symbolically graceful, mute swans are popular with many people. However, it is illegal to rehabilitate injured mute swans.
The DNR has a long way to go to bring mute swan populations to within management goals, but considers it an important step in successfully maintaining other native waterfowl populations - ducks, geese and even other swans.
For more information, visit www.michigan.gov/muteswans or call 517-373-1263.