Trumpeter swan which is apparent even when the swan is not standing or swimming upright) and larger, wedge-shaped bill as compared to the tundra swan. Trumpeter swans have similar calls to whooper swans and Bewick's swans. They are loud and somewhat musical creatures, with their cry sounding similar to a trumpet, which gave the bird its name. Beginning in 1968, repeated in 1975, and then conducted at 5-year intervals, a cooperative pan-continental survey of trumpeter swans was last conducted in 2015. The survey assesses trumpeter swan abundance and productivity throughout the entire breeding ranges of the three recognized North American populations: the
Trumpeter (bird) bronze iridescence, particularly on the wing coverts and the lower neck. In the best-known taxa the secondary and tertial flight feathers are white, grey, or greenish to black, and hairlike, falling over the lower back, which is the same colour. These colours give the three generally accepted species their names. Traditionally only three species of trumpeters have been recognised. In 2008 a review of the morphology of the dark-winged trumpeter resulted in the recommendation of splitting it into three species. In 2010 a review of the phylogeny and biogeography of all members of the family resulted in a total of