324 



BOARD OF AGRICULTURE. [Pub. Doc. 



caterpillars to their young, or feeding them, or both : black- 

 and-white warbler, blue jay, scarlet tanager, wood thrush, 

 chickadee, yellow-throated vireo, red-eyed vireo, crow, cat- 

 bird, black-billed cuckoo, yellow-billed cuckoo, yellow war- 

 bler and chestnut-sided warbler. 



Those birds which not only eat hairy caterpillars but also 

 feed them to their young are doubly useful, because of the 

 enormous amount of insect food required by young birds. 

 Our experiment shows that young crows weighing fifteen 

 and one-half to sixteen ounces require at least ten ounces of 

 food each day for their growth and development. Professor 

 Treadwell fed a young robin in twelve hours forty-one per 

 cent more than its own weight in worms. The same bird 

 consumed nearly half its own weight of beef in a day. 



Young birds must have animal food in order to grow and 

 develop rapidly, and this food consists mainly of insects. 

 An idea of the constant feeding required by the young may 

 be gained from the followino; brief account of the work of 

 two pairs of birds during the greater part of the day. 



On June 13, 1899, Mr. Mosher watched a pair of red- 

 eyed vireos feeding their young. There were three young 

 about a day old in the nest. It was near the ground and the 

 birds could readily be observed. The observer did not 

 reach the nest until nearly 7 a.m. (when the birds had 

 already been feeding their young probably for at least two 

 and one-half hours) and left at 5 p.m., at which time the 

 day's work was not finished, so that this cannot be consid- 

 ered a complete record of the day. Visits were made by one 

 or other parent, — 



Between 7 and 8, 14 times. 

 Between 8 and 9, 9 times. 

 Between 9 and 10, 12 times. 

 Between 10 and 11, 7 times. 

 Between 11 and 12, 16 times. 



Between 12 and 1, 9 times. 

 Between 1 and 2, 12 times. 

 Between 2 and 3, 15 times. 

 Between 3 and 4, 13 times. 

 Between 4 and 5, 18 times. 



making altogether 125 visits in ten hours. As these young 

 birds were very small, only a few insects were brought each 

 time, and most of those brought were so small that they 

 could not be positively identified ; but caterpillars form a 

 considerable part of the food of these birds at this season. 



