An exotic species in North America, the Mute Swan, a native of Eurasia, was introduced to this continent from the mid-1800s through the early 1900s. Individuals were imported to many areas of North America as an adornment to city parks and large estates, and for zoos and aviculture collections. All North American feral Mute Swan populations originated from the release or escape of individuals from these early captive flocks. The largest concentration of Mute Swans now occurs along the Atlantic Coast from Maine south to South Carolina; it has increased significantly since 1970 and shows few signs of slowing. Smaller flocks occur in the Great Lakes region and the Pacific Northwest.
One of North America's heaviest flying birds, the Mute Swan is highly territorial. It forms strong pair bonds and has few natural predators. Distinguished from other swans by its long, S-curved neck and its orange red bill with a large, black, basal knob, this species (in North America) is second in size only to the native Trumpeter Swan (Cygnus buccinator). The male is properly called a “cob,” the female a “pen.”
Mute Swans domesticate easily and historically have been kept in captivity; they have also been pinioned and released back into the wild, most notably in Great Britain since about 1186 ( Lever 1987 ). Adaptable, this species can be found in a variety of aquatic habitats, including municipal ponds, shallow saline embayments and coastal ponds, large, slow-moving rivers, and lakes and ponds.
As an exotic, feral species, the Mute Swan's effects on native ecosystems are of concern. Potential effects range from overgrazing aquatic vegetation to displacing native waterfowl. Strategies for controlling the expansion of Mute Swan populations include egg-addling (i.e., shaking), capture, and euthanizing of nuisance and escaped individuals.