Tol. XXIXI 

 1912 J 



Gross, The Yellow-hilled Tropic-bird. 



63 



merely the regurgitated juices and semidigested food from the 

 gullet of the parent bird. When the birds are between 15 and 30 

 days old, more than 90 % of the food consisted of squids, the 

 remainder being made up of small minnows and some unidentifiable 

 material. During the latter half of the young bird's life fish con- 

 stitutes a large part of the food, although many squids, some of 

 considerable size, were present in nearly every specimen examined. 

 It was not necessary, in most cases, to kill the bird in order to 

 make an examination of the food, for the young birds, especially 

 those of an age in which the instinct of fear was acquired, violently 

 regurgitated their food on the slightest provocation, even the mere 

 handling of the birds unaccustomed to my visits would cause them 

 to throw up the entire contents of their gullets. By taking advan- 

 tage of this simple means, it was easy to gain information about 

 the food without causing the birds any serious injury. Below 

 are lists of the animals, with their weights, which were found in 

 five such regurgitations of different birds ranging from 30 to 50 

 days old, arranged in the order of the ages of the birds, No. 1 

 being the youngest. 



No. 1. 



No. 4. 



