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 world 
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 
