PERCHING BIRDS. 135 
rookery was destroyed under the belief of the farmers 
that its inhabitants were hostile to their interests, and 
consumed a large quantity of corn. But mark the 
result. Two years passed away, and the farmers con- 
gratulated themselves on being rid of their winged foes, 
little thinking that they had other foes in their place 
whose approach was more difficult to detect. In the 
second year many fields of wheat suffered from wire- 
worm ; but in the third their ravages had become so 
general throughout the district as to occasion serious 
alarm. Little could be done to suppress their numbers 
until the rooks were again thought of, and the evil was 
traced to its true source. The rookery was permitted to 
be re-established by the return of many who had escaped 
the massacre, and who still cherished a partiality for 
their native trees, but who had hitherto been continually 
driven off. Their rapidly increasing numbers soon re- 
duced the insect pest, leading the farmers to acknow- 
ledge the error into which they had fallen, and henceforth 
to look upon the rook as a friend instead of an enemy. 
When rooks are feeding they always station several of 
their number as sentinels, and very faithful they are in 
sounding the alarm on the approach of a foe; they are 
not only vigilant in their watch, but evince a large 
amount of sagacity, an amusing instance of which was 
communicated to me by a friend on whose statement I 
can rely, and who witnessed the occurrence. 
A very large field had been sown with wheat, and in 
the centre a little hut had been erected to shelter the 
boy who had to tend the field, and to enable him to 
reach all parts of it. A gentleman who wished to obtain 
a few birds to hang up in his own fields thought this 
would be a good opportunity of procuring them, for they 
