360 ORNITHOLOGY AND OOLOGY. 



noxious insects in their different forms. It is perfectly safe 

 to say, that it would destroy a thousand insects in making 

 up the amount of food that I mentioned above ; and it is not 

 improbable, that, during this month, it actually eats that 

 number daily. 



During the first half of May, its labors are undoubtedly 

 beneficial ; for its food still consists almost entirely of in- 

 sects : but after the middle of that month, when the small 

 birds have begun to lay their eggs and hatch their young, 

 the Crow divides its diet pretty equally between them and the 

 insects. Now, it is not apparent, at the first glance, how 

 immensely injurious it becomes the moment it begins to 

 destroy the eggs and young of our small birds ; but we may 

 demonstrate it to an approximation. We will allow, that, 

 during the latter part of May, half of its food consists of 

 injurious insects and other vermin : it is therefore beneficial 

 in the whole month about twenty-three units. But it is 

 perfectly reasonable to say, that it destroys at least the eggs 

 or young of one pair of Sparrows, four in number ; one pair 

 of Warblers, four in number ; and one pair of Thrushes or 

 Starlings, four in number : for I have known one pair of 

 Canada Jays to kill and devour the half-grown young of four 

 families of Snowbirds (Junco liyemalis), sixteen birds in all, 

 in one forenoon ; and have seen a pair of crows, in two 

 visits to an orchard, within a half-hour's .time, destroy the 

 young birds in two robins' nests. 



Now, let us see what the injury amounts to that it does in 

 destroying the four eggs or young of the Sparrows, Warblers, 

 and Thrushes. It is a well-known fact, that the young of 

 all our small birds, whether insectivorous or graminivorous 

 in the adult stage, are fed entirely on insects. Bradley 

 says that a pair of Sparrows will destroy 3,360 caterpillars 

 for a week's family supplies. For four weeks, at the lowest 

 estimate, the young of our Sparrows are fed on this diet ; 

 and the family that the crow destroys would, in that time, 

 eat at least 13,440 noxious insects ; and, as they feed more 



