18 



apple trees. It was found almost impossible to complete the 

 experiments, as very many caterpillars were taken from the nets 

 by birds. I saw a chipping sparrow break through the nets and 

 secure a large caterpillar. More than 50 species of birds feed 

 on such hairy larvae, and Mr. Felt noted that 60 per cent of 

 the caterpillars used in these experiments were taken by birds 

 which broke into the nets. 1 



Quantity of Insects eaten by Young Birds. 



Fortunately the young of insectivorous birds grow almost as 

 rapidly as many of the insects on which they feed. Most of 

 the young of the smaller birds are well grown and able to fly 

 in from one to three weeks after they leave the egg. This rapid 

 growth calls for a tremendous amount of animal food. A 

 young robin fed by Professor D. Treadwell made no gain in 

 weight until the fourteenth day, when it received 68 angle- 

 worms. Later the same bird consumed in a day nearly one-half 

 its own weight of beef. A young man eating at this rate would 

 consume about 70 pounds of steak daily. 2 



Mr. C. W. Nash fed a young robin daily for fifteen days from 

 50 to 70 cutworms or earthworms. By experiment he found 

 that it would eat 165 cutworms in a day. 3 



Mr. A. H. Kirkland kept and fed some young crows. His 

 records show that on less than 8 ounces of food daily one bird 

 tended to lose in weight, and only when the food was increased 

 to 10 ounces was there a marked tendency toward a daily gain. 

 The digestion of many young birds is so rapid that the stomach 

 is emptied of food in from twenty minutes to two hours, ac- 

 cording to the character of the food eaten. 



Mr. F. H. Mosher watched two red-eyed vireos feeding young, 

 and found that in ten hours the parents together brought food to 

 the nest one hundred and twenty-five times. 4 



Professor Aughey states that during a locust year in Nebraska 

 he saw a pair of long-billed marsh wrens in an hour take 31 



1 Forbush, E. H., and Fernald, C. H.: The Gypsy Moth, Massachusetts State Board of Agri- 

 culture, 1896, pp. 215, 216. 



2 Treadwell, D.: Proceedings of the Boston Society of Natural History, Vol.6, pp. 396-399. 

 * Birds of Ontario in their Relation to Agriculture, Ontario Department of Agriculture, Bul- 

 letin No. 218, p. 64. 



Useful Birds and their Protection, Massachusetts State Board of Agriculture, 1907, pp. 45-52, 



