2iS Papers from the Marine Biological Laboratory at Tortugas. 



the noddy. Figures 23 and 24, plate 9, show the birds engaged in sunning. 

 The peculiarity in the reaction is that the birds always choose this one spot 

 (the one shown in the cut) in which to assemble. Occasionally the noddies 

 are to be found in the same spot. Figure 23, plate 9, shows the noddies 

 leaving the beach in advance of the sootics. They " sun " nearer to shore 

 than the sooties. Until we know more of the history of the life of the 

 sooty, it will be difficult to understand the meaning of this reaction. 



There is one rather interesting difference between the habits of the noddy 

 and those of the sooty which may be mentioned here : Every stake, buoy, or 

 possible resting-place upon the water is utilized by the noddy. It will sit 

 almost motionless upon any object projecting from the water for long periods 

 of time. This habit of theirs is like that found in the cormorants, boobies, 

 and pelicans which are present in the neighborhood. I have never observed 

 a similar reaction in the sooty. 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 in- 

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

 time in such maneuvers. I have never observed the noddies engage in this 

 reaction. 



In a note in the previous section, p. 212, we have already discussed the 

 possible disturbance which the frigate-birds produce in the life of the sooties. 



When I left the island, the oldest of the young sooties were about 30 days 

 of age. They were still in their juvenile plumage. From 20 days on, these 

 young birds could be found quite a distance from the nest, but the nest 

 locality still exerted its influence to a marked degree, both upon the parents 

 and upon the young, as shown by the fact that when one of the parents re- 

 turned from its feeding expedition it always alighted at or near the nest. 

 At the sight or the call from the parent, the young bird would hasten 

 toward the nest to receive food. This ability on the part of the birds to 

 approach within a few feet of a spot which to our eyes had no distinguishing 

 marks, but which had served as a nesting-place, is little short of wonderful. 



The care of the yotmg, especially from 20 days on, must be an exhausting 

 process for the parents. They become emaciated and somewhat bedraggled 

 in appearance. This is not to be wondered at when we consider that a 

 healthy young sooty can eat anywhere from 20 to 40 minnows of no insig- 

 nificant size in a day. It may be of general interest to note that after 

 the first few days the parent always recognizes and feeds its own young 

 and no other, and furthermore, the young tern recognizes its own parents 

 and attempts to feed only from them. Never but once out of many thou- 



