540 



THE POPULAR SCIENCE MONTHLY 



Pii;. 4. Robix ix Similar Phase of the Feeding Pbocess, but with yoimg at later 



stage of nest-life. Illustrating type of direct feeding, where one bird only is 



commonly served at each visit. After photograph by John B. Parker. 



to the nest itself or to the branches about it, and if hungry respond 

 with the greatest vigor and excitement. When response is dull or 

 lagging, however, the parent usually utters a call-stimulus, a peculiar 

 note, of low pitch, and varying in quality in different species; if this 

 should pass unheeded, it may become very shrill and rasping. 



Feeding the young in birds is either (a) a passive process char- 

 acteristic of certain precocious birds like gulls, in which the food is 

 regurgitated from stomach and gullet upon the ground (Figs. 11 and 

 12) or (b) it is very direct, in which case the food is generally in- 

 serted into the throat (Figs. 7 and 8), the common practise of altricious 

 birds. In the first instance, a young gull, the hatching of which was 

 witnessed, received its first food, consisting of small lumps of predi- 

 gested fish, when two hours old, and at the nest. Although this food 

 was placed within easy reach of the chick, and was even picked up and 

 held before its bill, no other encouragement was given and it was never 

 inserted into mouth or throat. 



The essence of the direct method of feeding is to test the swallow- 

 ing reflex of the nestling. The food may be carried in gullet or stomach, 

 and regurgitated from one or both to the mouth, before service, or it 

 may be carried visibly in the bill, as in robins and passerine birds gen- 

 erally, and fed direct from bill to throat, one bird only, as a rule, being 

 fed at each visit of the parent. Thus cedar-birds regurgitate mainly 



