486 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1917. 



and in feeding. The birds spend little or no time together except at night. 

 The one comes to the nest, the other flies away to feed. 



The period of incubation varies for the noddy from 32 to 35 days. This fact 

 was determined on the basis of 16 observations. The young began to appear 

 on the island about May 9 (1917). 



The young are cared for in the nest until they become strong enough to 

 leave it and live upon the ground. The young birds born in low nests, 

 even at a very early age (20 days and even earlier), clamber from them 

 with alacrity and hide in near-by bushes when danger is imminent. In 

 many cases these young birds can not get back to the nest. Under these 

 circumstances they remain near the nest locality, and the parents on returning 

 first alight on or near the nest and later hop to the ground and feed the young 

 bird. * * * 



As the young advance in age (20 days and at all later ages) the parent will 

 readily leave the nest when disturbed. The tendency in this respect is to revert 

 to the behavior exhibited during the egg-laying season. 



Examination of the stomach contents of both young noddies and Booties 

 showed the presence of representatives of the two families of fish, Carangidae 

 and Clupcidac. * * * 



The birds fish by following schools of minnows which are being attacked by 

 larger fish. The minnow, in its efforts to escape, jumps out of the water and 

 skims the surface for a short distance. The terns pick off these minnows as 

 they hop up above and over the surface of the water. * * * 



The birds feed singly or in groups, usually in groups. The group may be 

 composed of both noddies and sooties and may contain sometimes as many 

 as 50 to 100 individuals. All during the day groups of noodies and sooties 

 may be seen at work. As the minnows cease to jump above the surface of the 

 water, the group disbands and scatters in every direction. An instant later, 

 as an attack is made upon the minnows in some other locality, the birds im- 

 mediately rush there and renew their feeding. (See plate 21.) 



In this connection I would add that I have at such times seen 

 noddies dive for their prey with almost the same vigor that the 

 common and least terns engage in their pursuit. 



I will let Watson continue. 



Apparently, at the end of two hours the noddy has supplied its needs, for at 

 this time it returns to the island and relieves its mate at the nest. The latter 

 then comes out upon the water and takes, roughly, a two-hour turn at fishing, 

 then likewise returns to the nest. This routine of spending two hours at the 

 nest and two hours on the water is engaged in by all of the noddies during the 

 seasons of brooding and of rearing the young. 



Watson and Lashley also record an interesting and rather rare 

 habit. 



In 1910 we saw one noddy fly into the water, fold its wings, and begin swim- 

 ming like a duck. About 10 other noddies joined this one. This is the only 

 occasion upon which we have ever witnessed swimming movements. We have 

 never seen the sooty in the water, except when accident has overtaken it. 



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 al- 

 most 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. 



