THE FOOD OF NESTLING BIRDS. 295 



boring sorts, and the others were like the ants eaten by the 

 downies, the sorts that cultivate plant lice. Flickers 

 also eat borers, but they are much more largely ground 

 birds than are any others of the woodpeckers. 



All Mr. Judd's observations showed clearly that, 

 except pigeons and doves, the birds examined fed their 

 young first on animal food, and changed the diet only 

 gradually, and this only when the parent birds were not 

 insect- or flesh-eaters. This is due not only to the fact of 

 the soft, lax walls of the young bird's stomach, but also 

 to the other fact that animal food in general has a higher 

 nutritive value, and is more easily digested by the bird 

 than is vegetable food. 



Professor Samuel Aughey gives some interesting 

 figures calculated to show vividly how much a bird may 

 really accomplish in the destruction of insects. He 

 says: "During an outbreak of the Rocky Mountain 

 locusts in the 70's I saw a long-billed marsh wren carry 

 thirty locusts to her nestlings in one hour. At this 

 rate for seven hours a day, a brood would consume 

 two hundred ten locusts per day. And the passerine 

 birds of the eastern half of Nebraska, allowing only 

 twenty broods to the square mile, would destroy daily 

 162,771,000 of the pests. The average locust weighs 

 about fifteen grains, and is capable each day of consuming 

 its own weight of standing forage crops, corn and wheat. 

 The locusts, therefore, eaten by the nestlings would have 

 been able to destroy in one day 174,397 tons of crops, 

 which at $10 a ton, would have been worth $1743.97. 

 This case may serve as an illustration of the vast good 

 that is done every year by the destruction of insect pests 

 fed to nestling birds." (From Report of the Entomo- 

 logical Commission, 1900.) 



