174 



When man makes no efforts to destroy them, birds of every 

 species will multiply in proportion to their supply of food, on 

 the one hand, and to their shelter and conveniences for build- 

 ing their nests and rearing their young, on the other. Black- 

 birds diminish in numbers, while Robins multiply, as the coun- 

 try is cleared and cultivated, and the improved tillage causes 

 an increased supply of their insect food. This is because the 

 protection which the Robin receives is denied to the Black- 

 bird. But if men are disposed to complain of the larger pro- 

 portion of Robins in their own vicinity, let it be remembered 

 that the greater amount of land in high cultivation requires a 

 proportionally greater number of these birds to devour the in- 

 sects which are engendered by the more extensive cultivation 

 of the soil ; and if they are kept below this limit, the insects 

 upon which they feed will have an insufficient check upon their 

 over-multiplication. 



It is necessary, for the interest of agriculture, that birds 

 should be fully up to their supply of insect food ,• but this 

 cannot be, on account of the numerous ways in which they are 

 exposed to destruction ; by cats, by birds of prey, by gunners, 

 and by juvenile nest-hunters. It is the duty of legislators, 

 therefore, to make laws for their protection ; and to render 

 these laws effective, public opinion must be enlightened with 

 respect to the utility of birds ; and the people should be made 

 to understand that, as soon as the abundance of insects is in- 

 creased disproportionally to the number of birds that feed upon 

 them, their crops will suffer in the same proportion. Not an 

 acre of cultivated land in the whole country should be without 

 a pair of Robins ; and protection should be extended to all 

 other birds, except the rapacious tribes. 



