12 THE FOOD OF BIRDS IN INDIA. 



are beneficial, in very many cases they will prove to be diseased 

 or weak ; this destruction being then a benefit to the species. Again 

 many will be taken if abnormally coloured, the bird of prey being 

 the aid therefore in that natural selection which protects so many 

 forms of life from their foes. Young poultry suffer to some extent 

 from ravages by birds of prey, as well as from rats, mongooses and 

 snakes. These birds can be kept off to a large extent if not allowed 

 to breed in the vicinity, a fact already recognised by natives in some 

 parts of the country. It is during the breeding season that ravages 

 on poultry will mostly be committed by birds. On the other hand 

 there are numbers of birds which take nestlings and eggs from 

 smaller species ; while others will turn out some from their nests 

 (e.g., sparrows turn out martins) when they have built them, and 

 use the nest for themselves, so harrying these that nesting, and 

 therefore normal reproduction, are greatly interfered with and 

 checked. Both these cases, namely, destruction of young and eggs 

 of other birds and usurping their nests, should tell heavily against 

 the bird that does so, provided that the species the eggs belong to, 

 and the birds turned out of their nests, are of beneficial economic 

 importance. When considering, therefore, the economic importance 

 of any one species of bird from its food only, we realize how complex 

 a subject this is, and how much must be learnt about the bird under 

 all conditions of life before definite measures for protection or other- 

 wise can be adopted. 



Some birds are undoubtedly injurious to crops, &c., for part 

 of their lives, but before they can be classed as injurious their feed- 

 ing habits for the rest of their life must be carefully observed. 



As an instance of the above point, the Rosy Pastor (Pastor 

 roseus) is an excellent example combining both a marked beneficial 

 and a marked injurious action at different seasons. In some part 

 of the year it will, if allowed, do an immense amount of damage 

 to jowari when ripening ; at another the numbers of locusts it 

 destroys is enormous, and it also acts as an agent for limiting the 

 damage of locusts since by continuous persecution of these insects, 

 it drives them from one locality to another, thereby spreading the 



