Our Animals - Trumpeter Swan
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The Trumpeter Swan, Cygnus buccinator, is the largest native North American bird, if measured in terms of weight and length, and is (on average) the largest living waterfowl species on earth. It is the North American counterpart of the European Whooper Swan.
Males (also known as Cobs) typically measure from 145 to 163 centimeters (57 to 64 in) and weigh 11.8 kilograms (26 lb); females typically range from 139 to 150 centimeters (55 to 59 in) and weigh 10 kilograms (22 lb). The average wingspan is 2.03 metres (6.7 ft). It is rivaled in size among waterfowl only by the introduced Mute Swan, which is native to Eurasia, but the Trumpeter usually is longer-bodied. Exceptionally large male Trumpeters can reach a length of 183 centimeters (72 in), a wingspan of 3 metres (9.8 ft) and a weight of 17.2 kilograms (38 lb). The Trumpeter Swan is closely related to the Whooper Swan of Eurasia, and even has been considered the same species by some authorities.
These birds have white plumage with a long neck, a black bill subtly marked with salmon-pink along the mouth line, and usually has short black legs. Leg colors may vary.  The cygnets (juveniles) are grey in appearance, becoming white after the first year. The Mute Swan can easily be distinguished by its orange bill and different structure (particularly the neck, which is almost always curved down). The Tundra Swan more closely resembles the Trumpeter, but is quite a bit smaller and usually has yellow lores. Although extremely rare, Trumpeter Swans have been known to have yellow lores. Distinguishing Tundra and Trumpeter Swans from a distance (when size is harder to gauge) is quite challenging, and can often be done only with experience and knowledge of structural details.
Range and habitat
In winter, they may eat crop remnants in agricultural fields, but more commonly they feed while swimming. Their breeding habitat is large shallow ponds and wide slow rivers in northwestern and central North America, with the largest numbers of breeding pairs found in Alaska. Natural populations of these swans migrate to and from the Pacific coast and portions of the United States, flying in V-shaped flocks. Released populations are mostly non-migratory. In the winter they migrate to the southern tier of Canada, the eastern part of the northwest states in the United States and have even been observed as far south as Pagosa Springs, Colorado.
These birds feed while swimming, sometimes up-ending or dabbling to reach submerged food. The diet is almost entirely aquatic plants. In winter, they may also eat grasses and grains in fields. The young are fed on insects and small crustaceans along with plants at first, changing to a vegetation-based diet over the first few months. Predators of Trumpeter Swan eggs include Common Raven (Corvus corax), Common Raccoon (Procyon lotor), Wolverine (Gulo gulo), American Black Bear (Ursus americanus), Brown Bear (Ursus arctos), Coyote (Canis latrans), Gray Wolf (Canis lupus) and Northern River Otter (Lontra canadensis). Most of the same predators will prey on young cygnets, as will Common Snapping Turtle (Chelhydra serpentina), California Gull (Larus californicus), Great Horned Owl (Bubo virginianus) and American Mink (Mustela vison). Larger cygnets and nesting adults are preyed on by Golden Eagle (Aquila chrysaetos), Bobcat (Lynx rufus), Red Fox (Vulpes vulpes) and Coyote. Few predators, apart from the Bobcat and possibly the Golden Eagle, are capable of taking adults when they are not nesting.
Trumpeter Swan brood - The female lays 3-10 eggs on average in a mound of plant material on a small island, a beaver or muskrat lodge, or a floating platform. The same location may be used for several years. The eggs average 73 millimeters (2.9 in) wide, 113.5 millimeters (4.5 in) long, and weigh about 320 grams (11.3 oz). The incubation period is 32 to 37 days. These birds often mate for life, and both parents will participate in raising the cygnets, but only the female will incubate the eggs. The young are able to swim within two days and usually are capable of feeding themselves after at most two weeks. The fledging stage is reached at 3 to 4 months.
Adults go through a summer moult when they temporarily lose their flight feathers. The females become flightless shortly after the young hatch; the males go through this process about a month later when the females have completed their moult.