Trumpeter swan was still capable of flight due to its bulk. The adult trumpeter swan is all white in plumage. Like mute swan cygnets, the cygnets of the trumpeter swan have light grey plumage and pinkish legs, and gain their white plumage after about a year. As with a whooper swan, this species has upright posture and generally swims with a straight neck. The trumpeter swan has a large, wedge-shaped black bill that can, in some cases, be minimally lined with salmon-pink coloration around the mouth. The bill, measuring , is up to twice the length of a Canada goose's ("Branta canadensis")
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