LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 285 



panied by flocks of sooty terns and gannets, which appeared to be animated by 

 the wildest excitement. The terns hovered over the foaming sea, uttering shrill 

 cries and darting down into the water, evidently after food ; and in the midst 

 of the turmoil the blue-footed gannets swam about, beating the water with 

 their wings and adding to the noise made by the terns and leaping fish. While 

 on Maria Madre I saw a flock of terns some distance offshore, and, taking a 

 canoe, managed to get out to them and directly in the course of the school of 

 fish tliey were accompanying. Letting the boat drift I stood up and watched 

 the swarm go by. Thousands of large fish and hundreds of terns and gannets 

 passed the boat on every side, amid loud cries from the terns, a rushing sound 

 from the fish and gannets, and a bewildering complexity of motion in sea and 

 air that was intensely exciting. This novel sight was so interesting that I 

 came near losing a chance to secure some of the birds. 



Behavior. — Dr. Frank M. Chapman (1908) says of the flight of 

 this species : 



Sooty terns in fiight are much like common terns, and, when alarmed, they 

 have the common tern's habit of hanging in the air above their nests. Because 

 of their comparative tameuess and of the steadiness of the easterly trade wind, 

 an admirable opportunity was presented to observe these birds in the air at 

 close range. So even was the breeze that the birds, all facing it, seemed to be 

 suspendetl and motionless. There was, in truth, but little change in their posi- 

 tion, but it was maintained by constant adjustment to the slight variations in 

 the force and direction of the wind. Wings were raised or lowered, widely 

 spread, or partly closed ; tails depressed or slightly elevated, and fan-like, 

 opened or shut. In short, there was a ceaseless, if unconscious, effort on the 

 part of the birds to maintain the balance between gravity acting in one direc- 

 tion, and air pressure in another, and so well did they succeed that it was a 

 common sight to see one put its foot through its inner wing feathers and 

 .scratch its ear with as much ease as though it had been on its nest. 



Professor Watson (1908) noted that the sooty tern seldom, if ever, 

 perched upon the stakes, buoys, or other resting places, as the noddy 

 does, but spends most of its time on the wing when away from its 

 breeding place. He writes : 



I think the sooty always leaves the island and returns to it without at any 

 time having ceased its flight. This seems rather remarkable when we take into 

 account the fact that the sooty leaves the island in the early morning and 

 oftentimes does not return until toward nightfall. 



The sooties often soar round and round, getting higher and higher until lost 

 to sight. They usually join the frigate birds in this reaction. I am inclined 

 to think that the sooty when sufficiently fed spends a large part of its time In 

 such maneuvers. 



Audubon (1840) also remarks that this "species rarely alights on 

 the Avater, where it seems incommoded by its long tail ; " also that it 

 "never dives headlong and perpendicularly, as the smaller species 

 ai'e wont to do, but passes over its prey in a curved line, and picks it 

 up. Nor is the flight of this tern characterized by the buoyancy and 

 undecidedness, if 1 may so speak, of the other species mentioned 

 above, it being as firm and steady as that of the Cayenne tern, ex- 

 cepting during the movements performed in procuring its food." 



