140 ON THE INSTINCTS OF BIRDS. 
sufficient trial had been made of it, another was im- 
mediately resorted to. 
Chickens, in their early attempts to catch flies and 
other winged insects, show little or no address; but 
repeated failures teach them to use more circum- 
spection, and they soon learn to distinguish between 
an active vigilant prey and the inanimate substances 
on which they likewise feed. This cautiousness of 
proceeding is clearly the effect of information ob- 
tained by experience, and affords an example of an 
instinctive power being excited to activity by the 
intellect ; but a still more extraordinary instance of 
acquired knowledge is given by Montagu, in the Sup- 
plement to the ‘Ornithological Dictionary.’ This 
gentleman observed two Crows by the sea-shore 
employed in removing some small fish (the refuse of 
a fisherman’s net) from the edge of the flowing tide. 
They carried them, one by one, just above high-water 
mark, and there deposited them under large stones 
or broken fragments of rocks, after having amply 
satisfied the immediate calls of hunger. Now it must 
be conceded that these birds were aware that the 
advancing flood would sweep away their prize unless 
they conveyed it beyond the limit of its usual rise, 
or their conduct is quite inexplicable. It is equally 
plain that this knowledge, in the practical application 
of which they manifested so much foresight and 
sagacity, could be derived from observation and ex- 
perience only; because if it originated in a blind 
