wager] nesting song BIRDS 237 



be determined. Some times the old birds flew into the meadow 

 and at other times, and more frequently, over the thicket where 

 were wild gooseberry, cherry, haws, and other shrubs and trees. 



The parent birds were not observed to eat the masses of 

 excreta, though it is possible that they did. They always left 

 the nest quickly and flew some little distance with the masses in 

 their beaks. Xone were found to have been dropped near the 

 nest. 



The fact of the rapid increase in the weight of the nestlings 

 is in conformity with the observations made by many others. If, 

 however, we carrj- it over and assume a similar rate of growth in 

 the human young, it becomes especially striking. Assuming that 

 to a baby weighing seven pounds, food was supplied in a corres- 

 pondingly large amount, and that the baby could digest it with 

 equal facility, the baby would then grow to average adult propor- 

 tions and weight of 150 lbs. in less than a month. Xow after 

 the nestlings have left the nest, they are fed and cared for by 

 their parents for at least two weeks, before they begin to acquire 

 the ability to shift for themselves. Our baby, then, now grown 

 to adult weight, would receive further care and doubtless all of 

 his education, in a little over another month's time, after which 

 he would be expected to take his place in the world and shift for 

 himself. This rapid growth and development on the part of the 

 young birds is. of course, a remarkable adaptation since it per- 

 mits of their being reared while food is plentiful, and, too, en- 

 ables the young to harden and adjust themselves to their neces- 

 sities before the time of migration sets in. 



One cannot have observed birds such as these busy ones 

 bringing to their young, with ceaseless regularity, large numbers 

 of insect larvae, many of which are known to be destructive to 

 man's interests, without coming to an appreciation of the great 

 value of the bird. In addition to the song sparrow are many 

 others whose feeeding habits are similar. If not disturbed, many 

 species of birds nest within the area»of an acre, and in a square 

 mile there may be scores or even hundreds of nests. Multiply 

 then the work for a single day, of a pair of song sparrows by 

 scores of hundreds and one has the result of birds* efforts in 

 feeding their young. As a factor in keeping down the insect 

 hosts, they cannot be overestimated. They are one of Nature's 

 checks in preserving the balance. 



It is only fair to append the names of those who assisted in 

 the obser\-ation, since to them, as well as to the writer, belongs the 

 credit for this paper. They are : Louise Boswell. Bertha Cramer, 

 Myrtle Drury. Emma Foy. Marion Hayward. Alma Henricks, 

 Florence Moses. Ida Smith, Lola Swift, Genevieve \'ernor. 



