84 KEY TO THE BIRDS OF EASTERN NORTH AMERICA 
SUBFAMILY CYGNINAE. 
Swans. 
Bare skin, between the bill and eye; tarsus, reticulate; neck, very long; 
wing, over 19 inches long. 
General plumage, white; bill, black with yellow spot (adult); distance from tip of bill 
to nostril, less than distance from nostril to eye (immature birds are gray or brownish gray). 
Common on some parts of the coast. Olor columbianus. Whistling Swan. 
See No. 136. 
General plumage, white; bill, black, showing no yellow; distance from tip of bill to 
nostril, more than distance from nostril to eye. Chiefly foundin the interior of North America ; 
not common on the coast. Olor buccinator. Trumpeter Swan. 
See No. 137. 
Olor columbianus. 
General plumage, gray, or brownish gray; birds of this description may be the 
young of either of the above species, the difference in the distance from the bill to the eye 
being characteristic as in the old birds. 
