Page:Popular Science Monthly Volume 76.djvu/545

Rh from the gullet (Figs. 5 and 6), and the berries or insects come out entire, but covered with slime, more than one bird being quickly served at each visit. In woodpeckers and goldfinches, which are fed at longer intervals, the food comes up in the form of a "pap" or "mash," probably from the stomach in part, to judge from the outlines of the neck, and all are fed rapidly as before.

The nestling gives the "opening" response, and shows its "food-target," while the parent, if a robin, vireo or one of many altrices, "aims*" (Figs. 3 and 4) and inserts the food deep into the throat, presses it gently down, and watches it, watches, we may say for the swallowing reflex of the throat. If not quickly taken, the food is whisked out and passed around, one bird after another being tried in succession, until a throat with the proper reaction-time is found. There is commonly no distribution of food among the offspring, on any other basis than this. The youngster which can react most promptly, is thus favored, because he holds up most of the food; accordingly he grows fastest, and outstrips his competing nest-mates. The young cowbird drives the children of its nurse quickly to the wall because it reacts with greater vigor from the first, and interferes with any proper distribution of the food. It is not uncommon to see the same bird, usually the larger and stronger one, fed two or three times in succession, but the full gullet checks the swallowing reflex, and thus automatically applies a brake to the greediness of a nestling, which might otherwise gorge itself to suffocation.