Ducks, Geese, and Swans of the World: Tribe Anserini (Swans and True Geese)Ducks, Geese, and Swans of the World by Paul A. Johnsgard
Date of this Version1-1-2010
AbstractMute Swan Black Swan Black-necked Swan Trumpeter Swan Whooper Swan Whistling Swan Bewick Swan Coscoroba Swan Swan Goose Bean Goose White-fronted Goose Lesser White-fronted Goose Graylag Goose Bar-headed Goose Snow Goose Ross Goose Emperor Goose Hawaiian Goose Canada Goose Barnacle Goose Brant Red-breasted Goose The swans and true geese are moderately to extremely large waterfowl, which in common with the whistling ducks have plumage patterns that are alike in both sexes and lack iridescent coloration, and they also possess reticulated scale patterns on the tarsal surfaces. Most of the 20 species are found in the cooler parts of the Northern Hemisphere, the exceptions being 3 species of Southern Hemisphere swans. All are vegetarians, obtaining much of their food from terrestrial surface vegetation in the case of geese, and from subsurface aquatic vegetation in the case of swans. The patterns of the downy young tend to be pale and simple, without strong head or back patterning, and in most species the adult plumages are also fairly simple, with whites and blacks often predominating. The white plumage of most adult swans appears to be related to visibility needs associated with their high degree of territorial spacing. The most highly territorial swans are also the most strongly vocal ones, for the same reason. However, vocalizations of the sexes are very similar, and usually differ only in minor pitch characteristics. Most of the swans and geese are quite strongly migratory, but the insular Hawaiian goose not only has become nonmigratory but also has become semiterrestrial and has evolved reduced toe webbing as it has adapted to a mountainous existence on old lava fields.
Citation InformationPaul A. Johnsgard. "Ducks, Geese, and Swans of the World: Tribe Anserini (Swans and True Geese)" (2010)
Available at: http://works.bepress.com/paul_johnsgard/33/