Mute Swan

In the context of North America, the ornamental park swan. Introduced in the 19th century from Europe, where Mute Swans have long been domesticated (since the 12th century, according to numerous online sources). Native to northern and central Eurasia. Large, undeniably beautiful and impressive in flight (especially at close quarters), but despised by many serious birders and conservationists because they are aggressive and can be destructive of native species. Many are being killed in cull programs, especially on the East Coast and Great Lakes area, where the largest North American populations are established. My 1990 Peterson guide says, "Kept locally in parks; escapes not yet established" in reference to the Western United States. Clearly that has changed. Breeds at Ellis Creek Water Treatment Facility. Feral birds fairly common at Shollenberger Park. Despite the common name, Mute Swans make a variety of hissing and honking sounds. Wings produce a noisy hum in flight.

Adult birds are easily identified by large size, bright orange bill, conspicuous black knob above the bill, long neck usually held in an S-curve, and all-white plumage. Will sometimes swim with its wings raised and arched--the pose that is often transformed into designs for fanciful carriages, carousel seats, and pedal boats. Tundra Swan (Cygnus columbianus), the only other swan likely to be seen in Sonoma County, although common in the winter months only a few hours' drive to the north and east of us, is nevertheless only a rare winter visitor here. Adult Tundra Swan has a black rather than orange bill and lacks the black knob. There is usually a yellow spot at the lores in adult Tundra Swan. Tundra Swan holds its neck fairly straight, while Mute Swan is typified by a tendency to hold its neck in an S-curve. Trumpeter Swan (Cygnus buccinator) is highly unlikely in Sonoma County, so can probably be discounted. I don't believe there is any historical record of Trumpeter Swan in the county (although nothing's impossible; Trumpeter Swan has been reported at least once in neighboring Marin County--Rich Stallcup, 2005).

Difficulty may arise with juvenile Mute Swans, which look very similar to juvenile Tundra Swans. Juvenile Mute Swans may be quite white, but usually have considerable brownish grey on the head, neck, and wings (photo below). The color may persist to some extent into the first year. Juvenile birds have a pink bill and lack the black knob at the base. Juvenile Tundra Swans share these two characteristics, but there are important differences. The juvenile Mute Swan is likely to show the S-curve in the neck; the bird has a longer, pointed look at the rear; and the tip of the juvenile Tundra Swan's bill is more likely to fade into black. In both birds, the base of the bill appears to connect to the eye in a dark line. This line is more pronounced in Mute Swan and quite black. In Tundra Swan, the extension will usually be the pinkish color of the bill. The Peterson guides have good comparative illustrations. The National Geographic guides additionally point out that juvenile Mute Swans initially have a grey bill with black base that turns pink by midwinter.