124 HABITS OF BIRDS. 
I have seen,” he adds, “ eight or ten rooks come, 
upon such occasions, and setting upon the new nest 
of the young couple, all at once tear it in pieces in 
a moment. Such is the severity with which even 
native rooks are treated; but if a foreign rook 
should attempt to make himself a denizen of their 
society, he would meet with no favour: the whole 
grove would at once be up in arms against him and 
expel him without mercy.’”* 
Rooks, if we may judge from our own observa- 
tion, are more particular even than sparrows in,the 
circumstance of having sentinels while they are 
feeding in parties after the breeding season; for 
while providing for their young family, they, in 
general, cater apart. These rook sentinels are so 
vigilant, that it is by no means easy to get within 
shot of a foraging party; and hence it is popularly 
believed that rooks can smell gunpowder. We 
have often proved, however, that it is just as diffi- 
cult to approach them without alarming the senti- 
nels, when only carrying an umbrella, as when 
armed with a fowling-piece ; but that they seem to 
have some knowledge of firearms appears ‘from 
their being alarmed if a walking-stick is levelled at 
them, though no noise is made; a knowledge most 
probably acquired by the reiterated experience of 
having their nest-trees fired at when the young are 
fit to be made into pies. It is stated in some ac- 
counts of newly-discovered countries, that the birds 
were not at first frightened by the presentment of a 
fowling-piece, but soon became so after some ex- 
perience of its effects. We also think it not un- 
likely that the crows acquire part of the skilful vi- 
gilance which they exhibit as sentinels during the 
building of their nests, when one of a pair usually 
watches the nest while the other makes excursions 
to procure materials. 
* Animated Nature, iii., 168. 
