32 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 perpendiculai'ly in a last co- 

 lumn, and, when high aloft, wheel and twist 

 within their lines, which then resemble the coils 



