40 



If our experiments are conclusive, young crows require more 

 than half tlieir own weight of mixed animal and vegetable food 

 daily. If in computing the amount of food eaten by adult crows 

 we assume that they can live on half this amount, or only five 

 ounces of food per day, it is plain that one thousand birds would 

 consume three hundred and twelve pounds daily. If their food 

 on any one day consisted almost entirely of field mice, injurious 

 insects, wild berries and seeds, they would be, on that day, very 

 beneficial to the farmer. If, on the other hand, their food on a 

 certain day consisted of toads, the young or eggs of poultry and 

 wild birds, corn or other grains and cultivated fruit, they would be, 

 on that day, very injurious to the farmer. The question as to 

 whether the crow is beneficial or injurious depends entirely on how 

 the account balances at the end of the year. 



The crow cannot fail to be very valuable to agriculture if its 

 food habits are on the average more beneficial than injurious. If, 

 however, the balance is upon the other side, the bird may become 

 a serious pest. If in times of plenty its numbers increase beyond 

 all reasonable bounds it is likely to grow injurious in proportion to 

 its numbers. When crows become so plentiful in any locality that 

 they cannot find a sufficiency of animal food for their young they 

 are likely to turn their attention to poultry and wild birds, and also 

 to do more injury to farmers' crops. 



In summing up the evidence for and against the crow, it must 

 be admitted : first, that the crows injure the corn crop to some 

 extent, and some other crops slightly; second, they are somewhat 

 destructive to the eggs and young of poultry and wild birds ; 

 third, they distribute the seeds of poisonous plants ; fourth, they 

 destroy some beneficial insects, probably killing more than they 

 eat ; fifth, they eat large numbers of frogs and toads. On the 

 other hand: (1) the services of the crow in destroying noxious 

 insects can hardly be overestimated ; (2) crows are of great ser- 

 vice in destroying field mice and other small mammals ; (3) crows 

 are useful to some extent as scavengers. 



While it may be impossible with the data at hand to determine 

 the exact economic status of the crow in Massachusetts, the ques- 

 tion asked at the beginning may be answered in a general way. 

 The wholesale destruction of crows is said to have been followed 

 by a remarkable increase of injurious insects, and from what is 

 now known about the crow's food we may conclude that, unless 

 the birds become unduly numerous, they are likely to be of great 

 service to the farmer. It will pay the farmer to sacrifice some 

 portion of his products to the crow, provided he uses care that the 

 cunning bird does not overreach him in the bargain. 



