84 



KEY TO TIIK BIRDS OF KASTEKN NOUTH AMERICA. 



SUBFAMILY CYGNIN/E. 

 Swans. 



Bare skin, between the bill and eye; tarsus, reticulate; neck, very long; 

 wing, over 19 inches long. 



General plumage, white; bill, hlai-k with yi-ljow spot (adult) ; distance from tip of bill 

 to nostril, U's.s than distance from nostril to eye (immature birds are gray or brownish uray). 

 Common on some parts of the coast. Olur columhianus. Whistling Swan. 



See No. VM\. 



General plumage, white; bill, black, showing no yellow; distance from tip of bill to 

 nostril, more iliaii distance from nostril to eye. Chiefly found in the interior of North America ; 

 not common on the coast. 01<>r hnccinator. Trumpeter Swan. 



See No. V.M. 





...«S»i»,»W^''W'*'"''' 



Olor columbiiinus, 



General plumage, gray, or brownish gray ; biids of this description may l)e the 

 young of either of the above species, tiie diflerence in the distance from the bill to the eye 

 being ciiaracleristic as in tlie old birds. 



