The Maryland Department of Natural Resources has wrestled with the issue of invasive species for years. But, the story of the Mute Swan stands out among similar stories, mostly because many bird lovers have such affection for this beautiful, but environmentally destructive, species of swan. Here, an update on the agency’s efforts to resolve the fate of the Mute Swan in Maryland.
Despite their aesthetic appeal, mute swans can cause problems. The mute swan is native to Europe and Asia, but is an exotic species in the United States. In Maryland, a feral population of about 4,000 mute swans has become established from the original escape of five captive swans in 1962. The largest number of mute swans occurs in Talbot, Queen Annes, and Dorchester counties. Population growth and range expansion of this species has increased the number of swan-related problems for people and native wildlife.
Public opinion about mute swans is mixed. They are very large birds, measuring 56-62 inches in length. With little or no fear of humans, they are easily observed and provide opportunities for people to come in close contact with wildlife. Their vibrant orange bills with black knobs, white plumage and long, gracefully-held necks make them conspicuous. Their young, which have a dusky tinge and grayish bill, usually remain with their parents for about four months. Mute swans reside primarily in estuarine river habitats with smaller numbers on inland lakes and ponds.
Citizens frequently complain that mute swans reduce the availability of submerged aquatic vegetation, or SAV, to native wildlife, reducing recreational crabbing and fishing opportunities. Presently, we estimate that Maryland's mute swan population consumes about nine million pounds of SAV annually. Concentrations of mute swans have over-grazed bay grasses, eliminating habitats for crabs, fish, and other wetland dependent species.
In the early 1990s, a large molting flock of mute swans caused a colony of least terns and black skimmers, both state-threatened species, to abandon their nesting site on Barren Island in Dorchester County by trampling nests containing eggs and chicks. This was the only skimmer nesting colony in the Maryland portion of Chesapeake Bay. These swans also displaced nesting Forster's and common terns, declining species in Maryland. In other areas of the state, mute swans have also been documented killing mallard ducklings and Canada goose goslings.
* Maryland Department Of Natural Resources Page