323 



The Food of Nestling Birds. 



Howard E. Enders and Will Scott. 



The surprisingly rapid growth of fledgling birds is a matter of common 

 observation but the activities of the parents in the collection of food and the 

 care of the young is scarcely realized by persons who have not carried on 

 observations throughout the whole of a bird's working-day. 



It has been the practice of the authors, each summer, for a period of years,* 

 to assign students in groups of four to the work of observing the activities of 

 birds and their fledgling young from dawn until nightfall. The work was 

 carried on in relays such that two persons were at the nest at all times, one 

 to make the observations at close range with the aid of field-glasses, and the 

 other to make the notes. By this method it was possible to observe, time 

 and note in considerable detail, the activities of the birds, also the character 

 and number of pieces of food brought at each trip to the nest. 



Observations, many in duplicate, have thus been made upon seventeen 

 different species of the birds common to Winona Lake, Indiana. In the 

 several instances, the birds were under observation for a period of several 

 consecutive days, and we have reason to believe, without markedly modify- 

 ing their activities after the first hour or two. 



The object of the present paper is to indicate the nature, quality and 

 quantity of food brought to the young throughout a bird's full working-day. 

 A transcript of a single example is given in full while others are given in sum- 

 maries to indicate the number of feeds, number of pieces. Both "soft" 

 and "hard" food are fed to the young birds in proportions which change 

 somewhat with the age of the nestlings. 



It is contended that the stomach contents afford the only accurate and 

 reliable method of study of the food of birds. We believe that this method is 

 not applicable to the food of nestling birds for two reasons: first, the food is 

 soft and not readily identifiable; and the second and more important reason 

 is that the food is digested very rapidly. The stomach contents do not serve 

 as a criterion of the quantity of food that is eaten in the course of a day. 



♦Biological Station of Indiana University at Winona Lake, Ind. 



