THE COMMON CROW. 361 



or less upon the same diet during their stay with us, killing 

 certainly as many as fifty insects each daily, the family 

 would devour two hundred per diem, or, before they leave 

 us in September, as many as twenty thousand. The War- 

 blers are entirely insectivorous, and we can certainly allow 

 them as great destructive capacity as the Sparrows. The 

 four that the crow destroys would have devoured, before 

 they leave us in autumn, at least thirty thousand cater- 

 pillars and other insects. A pair of thrushes has been 

 actually seen to carry over a hundred insects, principally 

 caterpillars, to their young in an hour's time : if we sup- 

 pose that the family mentioned above be fed for only six 

 hours in the day, they would eat six hundred per diem, at 

 least while they remain in the nest, which being three weeks, 

 the amount would be 12,600 ; and before they leave us in 

 the fall, allowing only fifty each per day, — a very small 

 number, — they would, in the aggregate, kill twenty thou- 

 sand more. 



Now, we find that the Crow in one day destroys birds 

 that would together eat 96,040 insects before they would 

 leave us for their winter homes, or about ninety-six times as 

 many as it would eat in a day if its food consisted entirely 

 of them. It is therefore injurious, during the last half of 

 May, — keeping our original calculation in view, — 598 

 units. 



During the whole month of June and the first half of 

 July, while its family are in the nest, it is at least doubly 

 destructive ; for its young are possessed of voracious appe- 

 tites, requiring an abundance of food to supply them. Al- 

 lowing, then, that of its and their diet, half consists of insects 

 during this period, it is beneficial about forty-six units ; but, 

 as at least one-half of the other half consists of young birds 

 and eggs, it is injurious, during the same period, at least 96 

 units daily, or 4,320 units for June and the first half of 

 July. The remaining quarter of its and their food, during 

 this time, consists of berries and various small seeds and 



