THE COMMON ROOK. 131 



portion consists of this injurious plant. The object of 

 the bird in performing this service for us is to obtain the 

 larvae of several species of insects, underground feeders, 

 that prey on the roots, as Linnaeus long ago observed 

 upon the subject of the little nard grass (nardus stricta). 

 This benefit is partly a joint operation : the grub eats 

 the root, but not often so effectually as to destroy the 

 plant, which easily roots itself anew; but the rook 

 finishes the affair by pulling it up to get at the larvae, 

 and thus prevents all vegetation ; nor do I believe that 

 the bird ever removes a specimen that has not already 

 been eaten, or commenced upon, by the caterpillar. 



The rook entices its young from the breeding trees, 

 as soon as they can flutter to any other. These young, 

 for a few evenings after their flight, will return with 

 their parents, and roost where they were bred ; but 

 they soon quit their abode, and remain absent the whole 

 of the summer months. As soon however as the heat 

 of summer is subdued, and the air of autumn felt, 

 they return and visit their forsaken habitations, and 

 some few of them even commence the repair of their 

 shattered nests ; but this meeting is very differently 

 conducted from that in the spring ; their voices have 

 now a mellowness approaching to musical, with little 

 admixture of that harsh and noisy contention, so dis- 

 tracting at the former season, and seems more like a 

 grave consultation upon future procedure ; and as winter 

 approaches they depart for some other place. The 

 object of this meeting is unknown ; nor are we aware 

 that any other bird revisits the nest it has once forsaken. 

 Domestic fowls, indeed, make use again of their old 

 nests ; but this is never, or only occasionally, done by 

 birds in a wild state. The daw and rock pigeon will 

 build in society with their separate kindred : and the 

 former even revisits in autumn the places it had nestled 

 in. But such situations as these birds require, the ruined 

 castle, abbey, or church tower, ledge in the rock, &c., 

 are not universally found, and are apparently occupied 

 from necessity. The rooks appear to associate from 

 preference to society, as trees are common everywhere ; 

 but what motive they can have in view in lingering 



