Mitchell, Carl D., and Michael W. Eichholz. 2010. “Trumpeter Swan (Cygnus buccinator).” The Birds of North America, edited by Paul G. Rodewald. Ithaca: Cornell Lab of Ornithology. Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/truswa doi: 10.2173/bna.105