186 THE COMMON ROOK. 



on it, first pulling up the plant which concealed 

 it, and then drawing the larvae from their holes. 

 By what intimation this bird had discovered its 

 hidden food we are at a loss to conjecture; but the 

 rook has always been supposed to scent matters 

 with great discrimination. 



It is but simple justice to these often censured 

 birds, to mention the service that they at times 

 perform for us in our pasture lands. There is no 

 plant that I endeavour to root out with more per- 

 sistency in these places than the turfy hairgrass 

 (aira caespitosa). It abounds in all the colder parts 

 of our grass lands, increasing greatly when undis- 

 turbed, and, worthless itself, overpowers its more 

 valuable neighbours. The larger turfs we pretty 

 well get rid of ; but multitudes of small roots are 

 so interwoven with the pasture herbage, that we 

 cannot separate them without injury; and these 

 our persevering rooks stock up for us in such 

 quantities, that in some seasons the fields are 

 strewed with the eradicated plants. The whole 

 so "torn up does not exclusively prove to be the 

 hair-grass, but infinitely the larger portion con- 

 sists 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 



