Assertion: whooper swan | /r/HasProperty | c. cygnus
Facets:
Source sentences:
text: Bewick's swan is similar in appearance to the parapatric whooper swan (C. cygnus), but is smaller, shorter-necked and has a more rounded head shape, with variable bill pattern, but always showing more black than yellow and having a blunt forward edge of the yellow base patch.
text: Of the seven or eight species—some of them probably races of a species, as indicated below by scientific names in parentheses—five are all-white, black-legged birds of the Northern Hemisphere: the mute swan, with a black knob at the base of its orange bill, curved posture of the neck, and aggressive wing arching; the trumpeter swan (C. cygnus buccinator), named for its far-carrying low-pitched call and having an all-black bill; the whooper swan (C. cygnus cygnus), a noisy bird with black bill having a conspicuous yellow base; the similar but smaller and quieter Bewick’s swan (C. columbianus bewickii), of which Jankowski’s swan (C. columbianus jankowskii) may be merely the eastern race; and the whistling swan (C. columbianus columbianus), named for its voice and having a black bill with, usually, a small yellow spot near the eye.