160 ORNITHOLOGY AND OOLOGY. 



pounds of flesh a day, and drink five or six gallons of 

 water. 



The question immediately presents itself, How can this 

 immense amount of food, required by the young birds, be 

 supplied by the parents ? Suppose a pair of old robins, with 

 the usual number of four young ones. These would require, 

 according to the consumption of this bird, two hundred and 

 fifty worms, or their equivalent in insect or other food, daily. 

 Suppose the parents to work ten hours, or six hundred min- 

 utes, to procure this supply : this would be a worm to every 

 two and two-fifths minutes ; or each parent must procure a 

 worm or its equivalent in less than five minutes during ten 

 hours, in addition to the food required for its own support. 



After the thirty-second day, the bird had attained its full 

 size, and was intrusted to the care of another person during 

 his absence of eighteen days. At the end of that period, 

 the bird was strong and healthy, with no increase of weight, 

 though its feathers had grown longer and smoother. Its 

 food had been weighed daily, and averaged fifteen penny- 

 weights of weight, two or three earthworms, and a small 

 quantity of bread each day, the whole being equal to eigh- 

 teen pennyweights of meat, or thirty-six pennyweights of 

 earthworms ; and it continued up to the time of the pres- 

 entation of the report. The bird having continued in con- 

 finement, with certainly much less exercise than in the wild 

 state, to eat one-third of its weight in clear flesh daily, the 

 Professor concludes that the food it consumed when young 

 was not much more than must always be provided by the 

 parents of wild birds. The food was never passed undi- 

 gested ; the excretions were made up of gravel and dirt, 

 and a small quantity of semi-solid urine. 



He thought that every admirer of trees may derive from 

 these facts a lesson, showing the immense power of birds 

 ^to destroy the insects by which our trees, especially our 

 apple-trees, elms, and lindens, are every few years stripped 

 of their foliage, and often many of them killed. 



