Trumpeter Swan Facts

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Description:

The Trumpeter Swan is the largest waterfowl species native to North America. Most Trumpeters weigh 21-30 pounds, although large males may exceed 35 pounds. The male is called a cob; the female is called a pen. With a wingspan over 7 feet, these snow-white birds are truly spectacular. Standing on the ground, an adult Trumpeter stands about 4 feet high.

Trumpeter Swans belong to the avian Order Anseriformes, Family Anatidae, along with ducks and geese. Trumpeters have broad, flat bills with fine tooth-like serrations along the edges that strain water when the birds eat aquatic vegetation. Their long necks allow them to uproot plants in 4 feet of water. Trumpeters are often confused with the far more common Tundra Swan (formerly Whistling Swan, Cygnus columbianus), the only other native swan that occurs regularly in North America. Tundra Swans can be seen in the upper Midwest during spring and fall migration.

Observers have described the Trumpeter's call as resonant, deep and loud, sonorous, and trumpet-like. Hence the bird's name: Trumpeter Swan. The Tundra Swan has a high-pitched, quavering call resembling that of a Canada Goose (Branta canadensis) or Snow Goose (Chen caerulescens). From a distance the calls of a flock of Tundra Swans may be likened to the sound of a pack of baying hounds or distant 'whoops' and 'hollers.' Becoming familiar with these calls will aid identification.

The Tundra Swan has a 6 to 7-foot wingspan, weighs 13-20 pounds, and stands about 3 feet tall. Both species are white with a black bill. A swan in its first year is called a juvenile or cygnet. Juvenile Trumpeter and Tundra Swans are grayish. Tundra cygnets are more silver gray than the darker Trumpeter cygnets, which are sooty gray in the head and neck areas. Swan cygnets do not become all white until about a year old. In their first summer, Trumpeter and Tundra Swan cygnets have pink bills with black tips. The bills turn all black during the first winter.

One notable difference between these two species is the head and bill profile. The Tundra's bill is slightly dish-shaped or concave and is smaller in proportion to its smoothly rounded head. The bill of the Trumpeter appears heavy and somewhat wedge-shaped in proportion to its large angular head, similar to the head profile of a Canvasback duck.

Other field characteristics of the Tundra Swan include a distinct yellow spot in front of the eye on about 80 percent of the birds. In contrast, the Trumpeter Swan has a red border or stripe, like lipstick, on the edge of its lower mandible. This red border, however, may sometimes appear on a Tundra Swan's bill, and some Trumpeters may have a yellow mark in front of the eye. The best way to distinguish the two species is by their calls.

A third swan species is not native to the Midwest. The Mute Swan (Cygnus olor) is found commonly along the East Coast and is present in parts of the Midwest. The Mute Swan is a Eurasian bird first introduced by European immigrants. This is the swan that typically is featured in art work and folklore. Mute Swans are an undesirable exotic species that harass native waterfowl and uproot large quantities of aquatic vegetation. Almost all North American breeding populations of Mute Swans were established by the escape or accidental release of captive birds.

Close to a Trumpeter in size, the Mute Swan is easily distinguished from other swans by its orange bill and prominent black fleshy knob extending from the base of the bill to the forehead. Mute Swan cygnets have two distinct color phases: the royal phase (brownish) or the Polish phase (white). Unlike Trumpeter and Tundra Swan cygnets, the Mute cygnet has either a dark bill (royal phase) or pinkish bill (Polish phase) during its first summer; the bill turns orange during the first year.

Mute Swans typically hold their necks in an S-curve with the bill pointed downward. Though described as silent, Mutes actually utter a variety of call notes, including grunts and snorts.

Trumpeter Swans, although protected from hunting throughout their range, are also sometimes mistaken for Snow Geese, which can be hunted. The Snow Goose, however, is significantly smaller, with a wingspan of only about 3 feet and with black wing tips (all ages). Tundra Swans are hunted in North Carolina, Virginia, North Dakota, Montana, Nevada, and Utah.

Status and Distribution

Trumpeter Swans were once fairly common throughout most of the northern United States and Canada. Market hunting and the millinery trade rapidly depleted nesting populations during the 19th century. Swan skins were sold in the fur trade to Europe where they were used to make ladies' powder puffs and feathers were used to adorn fashionable hats.

Trumpeters nested in Minnesota and Wisconsin until the 1880s. In Minnesota, the species occurred in the prairie and parkland areas of western, central, and northern portions of the state. In Wisconsin, Trumpeters may have nested in all but the northeastern forested regions, most likely in large marshes or shallow lakes. Elsewhere in the Midwest, the Trumpeters' historic breeding range reached from western Nebraska to central Michigan. It extended as far north and east as James Bayin Canada.

Breeding Biology

Trumpeter Swans may form pair bonds as early as their second winter and some may nest for the first time at age three years. Most Trumpeters, however, don't nest until they are four to six years old. Trumpeter Swans mate for life and may live for 20 to 30 years. If one member of a pair dies, the survivor finds another mate. A cob usually replaces its lost mate with a younger pen and returns to the former nesting territory. When a pen remates, it also returns to its former nesting territory. As in other waterfowl species, remating and returning to a former nesting territory is more likely if the returning member of a pair was previously successful at raising young on that territory.

Swans usually form pair bonds where they spend the winter. Pairs may select a nesting area near where the pen hatched. The pen chooses the specific nesting area and the cob defends it, sometimes joined by the pen. If a pair spends at least two summers at the same nesting location, it will form an almost unbreakable attachment to the site.

A Trumpeter pair typically arrives on the breeding grounds soon after ice melt in early spring. For the first few weeks after arrival the pair engages in courtship behavior, bobbing their heads and quivering their wings while facing each other.

A newly formed pair usually does not build a nest during their first spring and summer together.

Trumpeter Swan nesting territories range from 6 to 150 acres in size. Large, shallow wetlands 1-3 feet deep with a diverse mix of emergent vegetation and open water offer ideal habitat. Such locations support a rich variety of submergent (underwater) plants used for food, such as sago pondweed and water milfoil. These are preferred by Trumpeters, along with such emergent plants as arrowhead, burreed, bulrush, sedges, and wild rice.

Nest-building begins in mid-April and may take up to two weeks. The nests may reach a diameter of 6 feet or more. Trumpeters build their nests on top of muskrat or beaver lodges, or they pile sedges and cattail tubers into a mound. The cob uproots the vegetation and transfers it to the pen, who piles it high, then uses her body to form a depression for the eggs. The same nest structure may be used from one year to the next. Usually, water surrounds the nest making it difficult for a mammalian predator to surprise the pair.

Beginning in late April to early May, the pen lays one off-white egg about 4 1/2 inches long and 3 inches wide every other day until a clutch of five to nine eggs is complete. If it is the pen's first clutch, fewer eggs may be laid and they may be infertile. Once all eggs have been laid, the pen incubates the eggs and the cob protects the nest against all intruders.

During the incubation period, which lasts about 33-34 days, the pen occasionally leaves the nest to feed, bathe, and preen her feathers. Preening is vital to maintaining the bird's plumage. When preening, a Trumpeter presses its bill against the base of the tail to extract a greasy fluid from an oil gland. This is used to recondition, clean, and waterproof the feathers.

When the pen leaves the nest, she covers the eggs with nest material. The cob, meanwhile, stands guard on or near the, nest to deter predators. Intruding swans or predators are vigorously chased away. The adults perform a "triumph display" after intruders are repelled. Facing one another, they quiver their wings and trumpet loudly.

When the cygnets hatch in June, they weigh about 7 ounces. After a day or two, they take to the water to feed on insects and other aquatic invertebrates. For the first several weeks, a cygnet may concentrate on this protein-rich food source to support its rapid growth. At early stages cygnets may gain 20% of their body weight every day.

By the time the cygnets are four to six weeks old they are feeding on aquatic vegetation, using their bills to uproot plants as their parents do. About this time the adult pair begins their annual molt. Flight feathers on the wings and tail are shed and replaced.

The pen usually molts first, two to three weeks after egg-hatching. The cob's molt follows after the pen has regrown her flight feathers. The molting period lasts about 30 days. Because even an adult is vulnerable to predators during this flightless period, the swans may seek shelter in tall emergent vegetation. Since the molt is staggered, at least one adult is always capable of flight and defending the cygnets.

The cygnets grow rapidly. Scapular, tail, and flank feathers begin to replace gray down when the cygnets are four weeks old. At six weeks, the belly, breast, and cheek are fully feathered. By seven weeks, cygnets have most neck and crown feathers. Cygnets have little down left at eight weeks and are fully feathered by nine to ten weeks though they are unable to fly until about 15 weeks of age. At 15 weeks the cygnets weigh about 20 pounds. Their growth rate exceeds a pound a week!

The first flights in late September are typically short. Daily practice prepares the cygnets to migrate with their parents just before freeze-up to wintering areas where ice-free streams and ponds allow subadults and unmated adults to mingle. Family groups and mated pairs keep to themselves. Parents and their cygnets return year after year to the same winter feeding sites. The quality and quantity of winter foods influences productivity during the next breeding season.

Cygnets will remain with their parents during winter and migrate north with them. Then the parents drive them away. By this time the cygnets are about one year old. They remain together in sibling groups until about two years of age when they, too, begin to seek mates and a new life in a remote marsh.

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Banko, W. E. 1960.
The trumpeter swan: its history, habits, and population in the United States.
N. Amer. Fauna. No. 63. U. S. Fish and Wildlife Service, Washington, DC. 214 pp.

Bellrose, Frank C. 1978.
Ducks, geese, and swans of North America.
Stackpole Books, Harrisburg, PA-540 pp.

Gillette, L N. and T. M. Dyhr. 1977.
A guideline for propagation of captive trumpeter swans.
The Trumpeter Swan Society, Maple Plain, MN. 24 pp.

Hansen, Skylar.
The trumpeter swan, a white perfection.
Northland Press, Flagstaff, AZ. 76 pp