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Yellowstone National Park Trumpeter Swan

The following are some facts about trumpeter swans that should help answer any questions you may have regarding this most interesting species.

The trumpeter swan gets its name from its trumpet-like call.

It is regarded as the largest of all North American wildfowl. Male mute swans can actually get larger at times, but the mute swan is not native to North America.

There are four species of swans that are considered free-flying in North America. Two are wild native species (trumpeter swan and tundra swan), one Eurasian species (whooper swan) is accidental in North America, and one species (the mute swan) escaped from captivity and is now a free-flying swan in certain areas of the country. The mute swan is the species of swan typically found in city parks, however it has the ability to overpopulate and is a sever threat to wild swans and other waterfowl. Mute swans are native to Eurasia and should not be encouraged in North America unless they are placed in a cage or are permanently incapable of flight. Wild swans need all the help they can get.

The trumpeter swan has a trumpet-like call whereas the tundra swan has a whistling call, and the mute swan is relatively silent.

In a standing position, trumpeter swans are approximately 4 feet high. However, if the neck and legs are outstretched they can measure nearly 6 feet long from bill to feet.

The wingspan (length from wing tip to wint tip) of the trumpeter swan varies between young and adults and between females and males. Wingspans in adults can vary from 6to 8 feet.

Male swans are called cobs, female swans are called pens and young swans up to one year of age are called cygnets.

Males are typically larger than females. Sexes can not be told apart, since both have identical white plumage with black bills and feet. Although cob and pen sizes can be told apart if they are side by side, there is still a fair degree of individual variation. Therefore, the only reliable way to sex individual swans is through a cloacal examination.

Trumpet swan cygnets are typically born gray in color and steadily lose their gray plumage becoming pure white by the time they are one year old. Sometimes rare white cygnets are born, these cygnets are termed leucistic meaning white, and retain white plumage throughout their juvenile and adult years. The bill of adult leucistic trumpeter swans remains black.

Adult male swans can vary from 21-32 lbs., but more typically weigh 26-30 lbs.

Adult female trumpeter swans weigh between 20-25 lbs, averaging about 21-22 lbs.

Trumpeter swans have been known to live 29 years in the wild, whereas a swan raised in captivity survived for 32 1/2 years. In the wild, however, typical survival age ranges from 15-25 years.

Trumpeter swans feed on submerged aquatic vegetation and on occasion aquatic invertebrates. Sometimes in the spring, they can be observed feeding on green grass. But this is very rare.

They feed in slow shallow water and dip their heads below the surface of the water. In deep water, they can only feed as deep as their neck will extend. Under these circumstances they balance with their legs and tail out of the water.

Every year adult swans go through a flightless period in which they molt all their feathers at once thus making them flightless for a 1-2 month period of time. This typically occurs during the warmest months, namely July and August.

A trumpeter swan nest commonly consists of a mass of emergent vegetation such as cattail or bulrush. It is large measuring 5 feet in diameter, 1-2 feet high, and weighing hundreds of pounds. Sometimes they will nest on a muskrat house or beaver lodge.

They build their nests in May, and the young usually hatch in June. The eggs are cream-colored, and they normally lay 4-6 eggs. The female does most of the incubating. It takes 33-37 days for the eggs to hatch.

Cygnets fledge (fly for the first time) in late September and early October. So it can take up to 110-120 days , to go from the time they are born to the time they fledge.

Trumpeter swans can fly between 40-80 miles per hour. They are very susceptible to collisions with wires, especially when they migrate.

There are basically two trumpeter swan flocks in Yellowstone., a resident year-round population and a migratory winter population. The resident population can vary from 28-55 swans, whereas the winter population varies from 75-119 swans.

Migrants that visit Yellowstone in the winter are a combination of swans from the Yellowstone/Greater Yellowstone area including swans from Canada (primarily Grande Prairie, Alberta).

Weather plays an important role in cygnet and juvenile swan survival and in swan productivity in general. Mild weather conditions usually are good for swan production. Higher winter survival also occurs during milder winters.

Nest flooding is the primary cause of nest failure. Egg predation by coyotes, ravens, and otters does occur.

Coyote predation is the major cause of swan mortality in the winter.

For the last five years, there have been 8-10 nest attempts per year, fledging 0-7 cygnets per year.

The Trumpeter Swan is one of the most imperiled birds in Yellowstone National Park. 2000 population estimates: 20 adults, 7 cygnets.

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