364 THE FOOD OP BIRDS IN INDIA. 



bird is so destructive in Behar as the Rose-ringed Parroquet. and 

 there is not a word to be said in its favour. 



Of other destructive birds, which should be destroyed, the Bee- 

 eaters, the House-sparrow and the common Indian Green Barbet 

 are the only ones included in the birds investigated here and which 

 occur commonly in Behar. 



What is the economic value of these birds which live in densely 

 cultivated areas, such as Behar ? One has only to read the lists of 

 the food of the beneficial species to get an idea of the immense part 

 they play in reducing insect damage. Nearly all insects have 

 special enemies such as parasites which attack each individually, but 

 which produce alternative abundance and scarcity of each insect ; 

 that is, with the natural action of the special checks such as parasites, 

 you get alternate " Waves " of insect pest and parasite ; this is 

 where the birds' importance is shown ; they are not restricted, they 

 eat many kinds of insects and when a pest has for the time got ahead 

 and is abundant, the birds are there to feed on it just because it 

 is abundant and because at one time one is abundant, at another 

 time another is, and the birds eat them all. To put it figuratively 

 they cut off the tops of the waves and tend to keep them all at a 

 uniform level, none being ever destructively abundant. In my 

 opinion from man's point of view this is the special function in 

 nature of birds and if the bird population is small, outbreaks of in- 

 sects are frequent. To gain a better idea of their action read over 

 the groups of insects they eat (pp. 323-345). Locusts and grasshop- 

 pers are all injurious and " they are eaten by practically every species 

 of insectivorous bird and form one of the main supplies from which 

 birds in India draw their food/' We have only one record of a 

 bird taking a mantis which is usually a beneficial insect. The in- 

 jurious bherwa (Schizodactylus monstrosus) is taken by many birds 

 as also are the injurious crickets. Termites (White-ants) are, when 

 they emerge from the nest in the flying state, eaten voraciously and 

 probably few escape. Yet every one of these flying females is cap- 

 able of starting a new nest if it can escape long enough to burrow 

 into the soil, and undoubtedly the birds destroy an enormous per- 



