150 BULLETIN 196, UNITED STATES NATIONAL MUSEUM 



feeding of the young and at all times take meticulous care of the 

 sanitation of the nest. The excrement is received in their beaks as 

 soon as it is emitted. The young are carefully examined and even 

 stimulated by a stroke of their bills after each feeding until the fecal 

 sac appears. During the first few days it is eaten, but thereafter it 

 may be carried away and dropped at some distance from the nest. 



The food at first consists of small green larvae, but as the young 

 become older, mature insects, small grasshoppers, moths, beetles, and 

 spiders are added to the diet. While the nestlings are very small 

 they are frequently unable to swallow the food brought to them. 

 After a morsel is thrust into an open mouth or into different mouths 

 without being swallowed, the adult will mince it in her bill, or if the 

 larva is large and both parents are present each will grasp an end and 

 pull it apart. Sometimes after repeated failures of the young to 

 swallow the food it is eaten by the adults. At one nest there seemed 

 to be a great deal of difference in the choice of the food delivered. 

 One of the birds would invariably bring food of the proper size and 

 tenderness, while the other would bring enormous larvae or winged 

 insects such as large sphinx moths totally unsuited as food for the age 

 of the young being fed. The latter may have been a young inexperi- 

 enced parent with its first offspring. Perhaps it was the male! At 

 least human fathers are not supposed to know much about proper 

 infant feeding. 



On the third day the eyelids of the young are parted, and from then 

 on their reactions are more and more responses to sight rather than 

 sound. On the fourth day the papillae of the remiges have pierced the 

 skin, and by the fifth day the chief feather tracts are welt defined. On 

 the seventh day the tips of the primaries and secondaries are un- 

 sheathed, and those of the other tracts have tips which display the 

 olive-brown and buffy colors. By the ninth day the young frequently 

 preen their feathers, thus facilitating the unsheathing process, so that 

 on the following day or two the full colors of the ju venal plumage are 

 acquired. The young now exhibit evidence of fear when one ap- 

 proaches or when there is a disturbance near the nest. The tail feath- 

 ers are well developed at this time but do not attain their full length 

 until later when they are about six weeks old. When the young are 

 12 days old they are ready to leave the nest. If they are Dot fright- 

 ened and not forced to leave the nest prematurely they are encouraged 

 by the adults, who stay away from the nest and perch at some distance 

 with an appetizing morsel in their beaks. The parents hop from perch 

 to perch calling constantly until the hungry youngster responds. At 

 such times I have seen one or more of the nestlings standing on the rim 

 of the nest preening their feathers, flapping their wings, and going 

 through all the gymnastics of a young osprey whose first venture away 



