Cygnus olor Gmelin, 1789

Unlike the tundra swans (Cygnus columbianus) that migrate to the Bay for the winter, the mute swan is a year-long resident, and, therefore, reports of conflicts with nesting native waterbirds and the consumption of submerged aquatic vegetation (SAV) have raised concerns among resource managers. Populations of black skimmers (Rynchops niger) and least terns (Sterna antillarum) nesting on beaches and oyster shell bars have been eliminated by molting mute swans. (Perry et al. 2002)

The mute swan Cygnus olor (Gmelin) is native to the Palaearctic but has also been widely introduced, both within its native range and elsewhere (Birkhead & Perrins 1986). In North America the species is viewed as an undesirable alien (Conover & Kania 1994). In Britain, since 1943, there have been reports of damage by mute swans to arable crops and to pasture (Eltringham 1963; Birkhead & Perrins 1986; Trump et al. 1994; Parrott & McKay 2001). Mute swans are also believed to have an adverse effect on brown trout Salmo trutta L. fisheries in southern England through overgrazing of aquatic macrophytes, especially Ranunculus spp. (water-crowfoot) (Eltringham 1963; Birkhead & Perrins 1986; Trump et al. 1994). (Watola et al. 2003)

Competition for space and food imposed by mute swans has the potential to reduce the quality and availability of breeding, staging, and wintering habitats for native species of migratory waterfowl in areas where feral populations of swans are established (Cobb and Harlan 1980, Allin 1981, Allin et al. 1987). This could be a particular problem around the coastal Great Lakes, given the already extensive reductions in availability of coastal wetlands in that region and the importance of these wetlands for staging native waterfowl. (Petrie and Francis, 2003)