The Behavior of Noddy and Sooty Terns. 201 



and a general fight would ensue. When the sexual reaction is in progress 

 it is a signal for the surrounding males to encroach. Coition is thus com- 

 pleted only after much fighting. I have seen the male attempt to mount 

 the female 12 to 15 times and at each attempt be interfered with by neigh- 

 boring males. 



The actual construction of the nest, when a nest-structure is formed, 

 begins after an undefended area has been found. The process of nest- 

 building is somewhat as follows : The bird puts the breast to the ground, 

 thereby supporting the body and leaving the legs comparatively free. The 

 feet are used as a combined 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 360° (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 depression 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. 



If we compare the behavior of the noddy during this period with that 

 of the sooty as described above, we find that the former is quietly building 

 its nest and engaging systematically in a fixed routine of instinctive activi- 

 ties. The contrast in the behavior of the two species is always marked, but 

 never more so than at this period of the nesting season. 



THE DAILY RHYTHM OF ACTIVITIES. 

 ACTIVITIES OF THE NODDY BEFORE THE EGG IS LAID. 



While observing the noddies at work upon the nest, it soon became 

 apparent that the daily routine of the female was different from that of the 

 male. From many hundreds of observations it was also evident that the 

 male feeds the female at more or less regular intervals. Incidental mention 

 has already been made of this dift'erence in the activities of the male and 

 female in the previous sections, but a more detailed statement is in order if 

 we are thoroughly to understand the economic conditions obtaining on the 

 island. 



After both birds have worked upon the nest for some time, the male 

 leaves and is gone for varying lengths of time, depending upon the ease 

 with which food is obtained. While he is away the female rarely leaves the 

 nest. She sits usually upon a nearby limb and rarely shows signs of 

 activity. It is not unusual to see four or five females thus sitting motion- 

 less and stupid for hours at a stretch. Observation at such a time becomes 

 exceedingly trying. Quiet is occasionally broken by the males from other 



