874 



The Book. 



[Dec, 



Before pronouncing a verdict upon the rook, let us consider 

 the significance of these figures from the point of view of the 

 food supplies of the country. 



From careful calculations we find that each rook consumes 

 about 16 oz. of food per week, or 52 lb. in a year. Accepting 

 this figure, as being probably reasonably accurate, it follows 

 that* 10, 000 rooks will consume in a year about 232 tons of 

 food, and in order to obtain this they destroy about — 

 80 tons of cereals, 

 32 tons of potatoes and roots. 



74 tons of beneficial insects. 

 65 tons of injurious insects, slugs, snails. &c. 



It seems clear that the birds examined preferred cereals to any 

 other kind of food. Further, we know that, generally speaking, 

 there is no scarcity of the kinds of insects upon which the 

 rooks feed, and that they could have eaten more, but that 

 they chose cereals, possibly as being easier to obtain in the 

 first instance and then as the result of an acquired taste. In 

 all probability there were too many birds feeding upon the 

 same kind of food in a given area, and that which was the 

 most plentiful and most easily procured was taken. 



Supposing the rooks had not destroyed this great bulk of 

 injurious insects, would these latter not have done as much 

 harm to cereals, roots, &c., as the rooks did? We think not, 

 as a considerable percentage would have been eaten by star- 

 lings, jackdaws and black-headed gulls. 



Moreover, there is fairly conclusive evidence that the rook 

 has rapidly increased during the last ten or fifteen years, and 

 records show that where the balance of Nature is disturbed in 

 this manner, a bird almost invariably changes its diet. In 

 other words, rooks are provinpj injurious because there are too 

 many of them. 



Even when reduced in numbers the rook would still continue 

 to feed upon cereals to a certain extent, but the percentage 

 would be considerably lower; in short, the benefits it conferred 

 would exceed the injuries it inflicted, and therefore it would 

 be to the ultimate benefit of the farmer to lose such a per- 

 centage of cereals in order to have destroyed the greater 

 percentage of injurious insects, &c., for by no other agency 

 could he so economically and so thoroughly attack these 

 particular pests. 



The conclusion we arrive at respecting the economic position 

 of the rook, therefore, is that there are now too many of this 

 species in the country and, as a result, too many birds feeding 



