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
Bird vocalization and prevent an energetically costly fight . In birds with song repertoires, individuals may share the same song type and use these song types for more complex communication. Some birds will respond to a shared song type with a song-type match (i.e. with the same song type). This may be an aggressive signal, however results are mixed. Birds may also interact using repertoire-matches, wherein a bird responds with a song type that is in its rival's repertoire but is not the song that it is currently singing. This may be a less aggressive act than song-type matching. Communication through bird