82 AUDUBON THE NATURALIST. 
of food—by the keenness of their vision, so that 
when skimming a barren track, they soar high, 
with extended front, in order to survey hundreds 
of acres at once. Finding the earth abundantly 
supplied, they fly low; and, when enticed to 
alight by a particularly plentiful spot, they hover 
round in circles to review it. The dense mass 
they then form, presents, during its evolutions, 
the most beautiful appearances ; now a glistening 
sheet of azure,—when their backs are in view; 
and, again, by sudden simultaneous change, a 
canopy of rich deep purple. Lost for a moment, 
midst the foliage, they again emerge, and, flap- 
ping their wings, with a rushing noise, as of — 
distant thunder, sweep through the forests to 
see if danger is near. Their aerial motions are 
‘so extraordinary as to resemble the action of 
military discipline. In the process of throwing 
up the withered leaves, in search of food, the 
rear ranks pass continuously over the main 
body, alighting in front, in such rapid succes- 
sion, that the whole force seems still on wing, 
If menaced by a hawk, they rise suddenly with 
the might of a torrent, and pressing into.a solid 
mass, dart forward in undulating lines, descend 
and” sweep close over the earth with wonderful 
velocity, mount perpendicularly in a yast co- 
lumn, and, when high aloft, wheel and twist 
within their lines, which then resemble the coils 
