246 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. 



they abound the terns congregate and busily bombard the water, disappearing 

 completely below the surface in order to capture their prey. As the bird rises 

 from the water, with the fish hanging from its bill, it occasionally throws it into 

 the air either from pure fun or to get a better hold on the fish. Sometimes a 

 bird drops a fish, but catches it again before it has fallen more than a yard 

 or two. The presence of the fish in the mouth never interferes with the capacity 

 of the bird to scream or cry out. In fact, the fish bearer generally screams 

 constantly, as if to announce its success in the chase or the fact of food to its 

 young. 



Behavior. — The flight of the common tern, like that of all of its 

 congeners, is light, airy, and graceful. At times it seems listless and 

 desultory, as it flits along the shore looking for its prey, the slow 

 beats of its long wings lifting its light body at every stroke; but 

 again it is swift and direct when traveling high in the air or when 

 hurrying to join a bevy of its fellows hovering over a school of fish; 

 but always the bird has better control of its movements than it 

 appears to have. Its diving habits have been described above. It 

 seldom indulges in swimming, though it can do so if necessary. On 

 hot days large numbers may sometimes be seen swimming and 

 bathing. 



In life the common tern can not be easily distinguished from the 

 Forster's tern, and it still more closely resembles the Arctic tern; 

 the movements of all three are almost exactly alike, and the common 

 tern is intermediate in color between the other two. Its voice will 

 distinguish it from the former, but not from the latter. Its some- 

 what harsh rolling call, " tee ar-r-r-r-r," is almost musical at times 

 and has a decidedly pleasing cadence, a tinge of wildness, associated 

 with the poetry of summer seas. There is a delightful variety in its 

 notes, with the repetition of the same theme, varying in rapidity 

 and tone, expressive of its various moods. Doctor Townsend writes 

 to me in regard to it : 



I have had them fly directly at my head to within a few feet, when they 

 suddenly swerve upward. As they dart down they emit in their rage a rapidly 

 repeated and vibratory tut tut or kik kik kik, followed by a piercing, screaming 

 tear. These sharp rapidly repeated notes are sometimes followed by a loud 

 rattling sound, as if the mandibles were vibrated in anger. 



The Muskeget terns have suffered seriously at times by the intro- 

 duction of cats, kept by the life-saving people, which also nearly ex- 

 terminated a local species of field mouse {Microtus hreiveri). Per- 

 haps their worst enemy, next to. man, has been the short-eared owl. 

 A colony of these owls lived on the island, making their home on 

 some high grassy knolls, about which hundreds of dead terns lay, 

 partly eaten and drying in the sun. Mr. William Brewster (1879) 

 has thus described their destructive work : 



Every day at a certain time these owls sallied forth in search of fresh prey. 

 We used regularly to see them about sunset, sailing in circles over the island 



