62 



Gross, The Yellow-hilled Tropic-bird. 



fAiik 

 LJan. 



Table of Measurements (^Continued). 



The above table of measurements is made from the studies of two birds 

 which stand one at either end of the series. The two life histories seem 

 to overlap but match comparatively well at the 33rd day of development. 

 The age of the older bird is only approximately known (within 4 or 5 days), 

 since the measurements of different young of the same age may vary as 

 much as the growth of four or five days. 



The weights of the young birds fluctuated a great deal from day 

 to day; this was due to the fact that they were weighed in the 

 morning after feeding time. A series of weighings made during 

 the night, or very early morning before any food has been received 

 by the young birds, would undoubtedly be less variable. 



One of the young at the time of hatching when thoroughly dry 

 and before it was fed weighed 25 grams, or 19 grams less than the 

 egg from which it hatched. Another young bird weighed on the 

 day of hatching 30 grams; but this individual was not watched 

 and therefore it may have received food. 



The food of the young during the first 10 or 15 days consists of 

 snails and soft marine animals. In some cases it seemed to be 



