42 



KEY TO THE BIRDS OF EASTEIJX NORTH AMERICA. 



Forster's Tern. Winter. 



Roseate Tern. 



Common Tern. 



Least Tern. Gull-billed Tern. 



-^ 



Adult Terns (except the Noddy) have the top of the head entirely black, part of the year, varying with age 

 and season. 



