LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 245 



Occasionally in young birds the first nuptial plumage, described 

 above, is not assumed, but instead a plumage like the adult winter 

 plumage is acquired by a late prenuptial or an early postnuptial 

 molt. This plumage is worn throughout the spring and summer, 

 probably by the less vigorous birds which do not breed. It is the 

 plumage which was once described as a species under the name 

 Sterna portlandica. 



Adults have two complete molts each year, a prenuptial early in 

 the spring, before their arrival on their breeding grounds, and a post- 

 nuptial in September or later. The adult winter plumage is similar 

 to the first winter except for the wings and tail ; the latter is shorter 

 than in spring. 



Food. — The food of the common tern consists almost wholly of 

 small fish, not over 3 or 4 inches long, such as the sand launce 

 (Ammodytes americanus) and the pipe fish (Siphonostoma fuscum) , 

 and probably the young fry of larger species. Shrimp and aquatic 

 insects are eaten to some extent. Mr. Ora W. Knight (1908) speaks 

 of seeing a tern chase, catch, and devour a yellow swallow-tail butter- 

 fly (PapiUo turnus). The fishermen about Nantucket find the terns 

 very useful in helping them to locate a school of bluefish, for a hover- 

 ing, diving flock of terns is almost sure to indicate the presence of the 

 fish. The small fry on which the bluefish feed are driven to the 

 surface in dense schools to escape from their enemies below only to 

 be pounced upon by their enemies in the air. It is remarkable to see 

 how quickly the terns will gather, from far and near, as soon as one 

 of their number has discovered such a school. It is an exciting scene, 

 for the water fairly boils with rushing, plunging fish, and the air is 

 full of screaming, fluttering, diving birds ; but for the poor fry it is 

 a strenuous struggle for existence. 



Doctor Townsend describes its feeding habits as follows : 



The plunge of the common tern resembles In miniature that of the gannet. 

 Down they drop like winged arrows, folding their wings as their bodies enter 

 the water. Often they disappear entirely under the water to emerge victorious, 

 with the fish in the bill, or prepared to try again. They scream their triumph 

 or failure, for they can scream even with a fish in the bill. Sometimes a fish 

 is diflicult to swallow, and it is dropped to be caught again before it strikes 

 the water. As the terns leave the water they generally shiver violently, 

 probably to shake off the water. At times they fly down at the beach for a 

 small crustacean or a sea worm. Off the southern Labrador coast I have 

 seen flocks of terns follow small whales and dart down screaming at the water, 

 after the whale had broached and gone down. It is probable that the whale 

 and tern both relish the same small fry. 



During the month of August one of this tern's favorite food fishes, the 

 sand eel or sand launce (Ammodytes americanus), abounds in the shallow 

 waters about the beaches and inlets at Ipswich, Massachusetts, and thither 

 the terns flock in large numbers from distant breeding places. These fish 

 are 3 or 4 inches long and swim in compact schools of many hundreds. Where 



