The BeJiavior of Noddy and Sooty Terns. 237 



THE DEVELOPMENT OF THE YOUNG NODDY IN CAPTIVITY. 



The following study of the development of the young terns in captivity 

 is based both upon field observations and upon the observation of young 

 birds reared in captivity. I was enabled to rear 3 young noddies and 8 

 young sooties from birth to 30 days of age.^ At the end of 30 days they 

 were still in good health, but I was forced to leave the island on the i8th of 

 July, consequently my observations are concerned only with these first 30 

 days of the life of the young terns. - 



On account of the great difficulty of securing suitable food, the rearing 

 of the young terns entailed enormous labor both on my own part and on 

 that of my servant. Each morning it was necessary to take a seine and a 

 power-boat in order to catch a supply of minnows for the day. During the 

 first few days of their lives, the young terns can swallow only very small, 

 perfectly smooth fish. In order to keep the fish in good condition it was 

 necessary to tow a live-fish car with us, into which the minnows could be 

 emptied as soon as caught. During the first week, the young birds were fed 

 about five times a day. This consumed an enormous amount of time. 

 Each bird had to be fed individually and only one fish at a time could be 

 given. When one considers that a young, live, healthy tern can eat from 12 

 to 40 minnows a day, depending upon the age of the bird and the size of the 

 minnows, one can form some notion of the labor entailed in rearing the birds. 

 The main difficulty we experienced was in catching the fish. On stormy 

 days it was almost impossible to seine successfully, and even on some fair 

 days, for some inexplicable reason, the fish were not to be found near the 

 shore on any of the islands. As the season advanced, the minnows became 

 scarcer and scarcer. The fact of the increasing scarcity of fish during July 

 and August will be a serious handicap in the future for anyone who may 

 desire to rear these birds and observe their growth for a longer period of 

 time than the above. 



First day: 



The young noddies began to appear on the island about June 9 (1907).^ 

 The first few hours after birth they are extremely helpless. During the 

 first day of their life they exhibit few signs of fear, making little effort to 

 shrink away from the hand. However, their eyes are very mobile. The 8 

 young birds which I observed on the first day were able at 5 hours of age 

 to maintain the head and body fairly well in a standing position. At the 



' I began with 8 noddies and 12 sooties, but owing to my attempting to feed them 

 upon " salted fish " during a scarcity of live fish, 5 noddies and 4 sooties died. 



' The photographs of the young terns serve roughly to show some of the stages 

 in their development during the period in which they were under observation. Sooties 

 I day, 3 days, 8 days, and 30 days of age are shown on plate 3. Noddies i, 3, 18, and 

 30 days of age are shown on plates 4 and 5. 



' About 65 per cent of the young are born with black plumage, the other 35 per 

 cent are born almost pure while. Thinking this might mean a sexual difference. I 

 asked Dr. Charles R. Stockard to make an anatomical investigation. It appeared that 

 the color at birth is not correlated with sex. 



