Fig. 10. Goldfinches Pyramid of Five Young and One Adult at later Stage in Nest-life. Type of direct feeding by regurgitation, where all birds are served at each visit, and some more than once. Note uniformity in response and in size of the nestlings.
The initial instincts of the young depend upon the degree of development attained at birth, and are manifested in every phase from a precocious bird like the snipe, which is horn seeing and with a full coat of down, to the altricious cedar wax wing, which is stark naked, and is blind up to the second or fifth day. The precox emerges with feathers wet with the amniotic fluid, and remains at the nest at least long enough to dry off, while the more slowly maturing hawk or eaglet, though down-clad and alert from the first, is tended for weeks or months at the nest. MacPherson, who has described the home life of the golden eagle, which he carefully watched on a cliff in the highlands of Scotland, found that the young were fed at the eyrie eleven weeks before they were ready for independent flight.
The initial responses of the altrix, of which the cedarbird, and, with some qualification, the cuckoo, may be taken as a type, to be seen at birth or shortly after, are (a) the power of orientation, (b) the grasping reflex of the feet, (c) the food-response, (d) the call note, and (e) the characteristic actions in muting, following feeding, as a result of the stimulus of food, and possibly of the attitude of inspection assumed by the adult. Later follow other specific call and alarm-notes, pecking, gaping, stretching, spreading in response to heat, preening, bristling and certain attitudes expressive of fear, flapping and flight.
