The Horticultural Value of the Crow. 47 



during these months may be called beneficial ; although the good resulting 

 from them is of so little amount, that we might safely regard them as 

 neutral. But, to be beyond the chance of doing it an injustice, we will 

 assume, that, during the three months above mentioned, the crow does as 

 much good as during the whole month of April. 



Let us adopt, in this discussion, a system of numerals to signify the 

 relative values of this bird through the year; taking the unit i to represent 

 the labors of each day. The crow is therefore valuable, during January, 

 February, and March, 30 units : and, in April, is unquestionably 30 units 

 more ; for its food then consists almost entirely of 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 insects : 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 23 

 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 snow-birds {yunco hyemalis) — 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 



