80 FOOD OF THE YOUNG 



But altricial birds which may be hatched at longer intervals are 

 brooded more or less constantly for days or until their own feathers 

 are sufficiently grown to protect them. Even then, when exposed to 

 rain or sun, the parent may stand above them with half-spread 

 wings. 



Food. The young of prsecocial birds feed themselves, but either 

 learn by experience or are taught by their parents what they shall eat. 

 Recall a Hen clucking to her chicks and picking up and dropping bits 

 of food she desires them to have. Even the act of drinking is not 

 instinctive. (See especially Lloyd Morgan's ''Habit and Instincts.") 



The young of altricial birds, not only when they are in the nest, but 

 as long as a month after leaving it, are fed by the parents. The nature 

 of the food and the manner in which it is given are subjects of far too 

 great import to be adequately treated here. The food, at first, is usually 

 more or less digested in the crop or stomach of the parent whence it is 

 regurgitated into the mouth of the young. With Passerine birds, this 

 method, when employed, is soon abandoned, and food in a more or 

 less natural state is captured and given directly to the open-mouthed 

 offspring; but the Flicker, Hummingbirds, and Doves, for example, 

 feed only by regurgitation, inserting their bill far into the mouth of 

 their young. 



Young Pelicans, Cormorants, Water Turkeys, Spoonbills, and 

 Ibises thrust their bill down the throat of their parents. Flamingoes 

 introduce the tip of their great bill into that of their single chick, giving 

 it, by regurgitation, a few drops of predigested liquid food, an exceptional 

 method of feeding among prsecocial birds; young Herons grasp the bill 

 of their parent at the base with their own, as one would with a pair 

 of scissors, when the old bird either disgorges food into the nest or skill- 

 fully into the mouth of the young. Hawks tear the food into bits 

 and give it to their young, and larger insects are beaten or pulled 

 apart by Passerine birds, both parents sometimes working together at 

 the task. 



The young of Passerine birds are fed every few minutes throughout 

 a greater part of the day, but the young of larger birds are waited on 

 less frequently, hours often elapsing between meals, at which, however, 

 they receive large portions. 



The rate of growth of young birds, particularly of young perching 

 birds, is little short of marvelous. Herrick ('08, p. 187) writes of a 

 young Cedar Waxwing the weight of which "doubled on the first day, 

 more than trebled on the second, and nearly quadrupled on the third. 

 On the twelfth day, when it weighed approximately one and one-fifth 

 ounces, and had increased in weight thirteen-fold, it left the nest." 

 "At a corresponding rate of growth," he adds, "a ten-pound baby when 

 one day old would weigh twenty-one pounds, and at the age of twelve 

 days one hundred and thirty-four pounds." A young Song Sparrow, 

 studied by Owen, weighed, on hatching, 2.9 grams, and when at the 

 age of seven days it left the nest, 16 grams. (The Auk, 1899, p. 222.) 



