Fig. 4. Robin ix Similar Phase of the Feeding Progress, but with young 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 characteristic 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 inserted 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 predigested 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 swallowing 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 generally, 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
