478 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



bined scraper and shovel. A few backward strokes of the feet are made, which 

 serve both to loosen the sand and to remove it from beneath the body. The 

 bird then turns slightly and repeats the process. When it has turned 3GO (or 

 less) it begins to use the breast as a shaper. By continuing this process, the 

 depression is soon made to assume the required diameter and depth. My notes 

 show that the bay cedar leaves are often gathered up and placed around the 

 rim of the nest as the hole is being dug. I can not say which sex does the work, 

 but I believe that both male and female engage in it. As soon as the depres- 

 sion is made, both birds begin to defend it. Naturally, where no nest is made, 

 the nest site alone is chosen and defended as described above. 



An approximate count of the total number of the sooty nests was made in 

 1908 in the following way : Those parts of the surface of the island containing 

 nests were subdivided into 10 separate areas. The number of square feet in 

 each area was next determined. The average number of nests (spots where 

 eggs were deposited) per square foot was then determined separately for 

 each area. By means of these data, the total (approximate) number of nests 

 on the island was found to be 9.429. Multiplying by two, as in the previous 

 case, we have 18,858 as the total number of adult sooties. It may be said that 

 the above determination was made late in the brooding season, after all the eggs 

 had been laid. It may also be of interest to note that in localities where the 

 nests are very numerous they often are not more than 10 to 12 inches apart. 



Plates 5, 6, 8 show the disposition of the nests, for each bird in 

 the picture is occupying his home. 



The sooty usually lays but one egg, though occasionally two are 

 deposited. Watson found only 25 nests containing more than one 

 egg in all the thousands examined and but a single one in which two 

 birds were actually hatched and reared. On plate 8 are figured five 

 eggs selected to show the greatest range of color variation observed, 

 for although the general type of coloration is very similar, a con- 

 siderable diversity is found to be present when one actually searches 

 for variations from the typical form which is represented by the 

 figure. 



Watson gives us an intimate picture of the changes that take place 

 in the habits of the adult bird during the various stages of the 

 cycle that begins with nest building and probably ends with the 

 birds leaving the island. He has with infinite patience worked out 

 the daily life routine, with all of its vicissitudes, of the young bird 

 from the time it breaks from the shell until it finds its wings. I shall 

 therefore let him speak. 



The general disposition of the sooty, like that of the noddy, changes after the 

 egg is laid and in the same way. Some of them become far bolder than the 

 noddies in a corresponding situation. It was possible for me to lie down within 

 a few inches of a brooding sooty and have it remain on the nest indefinitely. 

 If the hand is extended toward the sooty it will attack vigorously, but I 

 have never had a group of flying sooties attack me as I approached the vicinity 

 of their nests, as was sometimes the case when I ventured too near the nests 

 of the noddies. The birds are very variable in this respect. When one ap- 

 proaches a neighborhood containing many nests, the majority of the birds will 

 fly up into the air, circling round and round, screaming all the while. If one 

 remains quiet, the birds will gradually return and cover the eggs. Gradually 



