SOLITARY AND GREGARIOUS. 125 
The sentinels of gregarious birds were observed 
by the ancients, and legends told of them no less 
exaggerated than those of our modern crow-courts. 
‘““The cranes,” says Aristotle, as we may translate 

Crane. 
the passage, “have a leader, as well as sentinels 
placed in their rear rank, so that their alarm-call may 
be heard.”* Pliny gives a still more minute detail of 
their proceedings. Speaking of their migration, he 
* Hist. Anim., ix., 10. 
L 2 
