94 The Naturalist in La Plata. 



such an instinct as that ; and in regions where hawks 

 are extremely abundant most of the birds would be 

 in a constant state of trepidation. On the pampas 

 the appearance of the comparatively harmless 

 chimango excites not the least alarm among small 

 birds, yet at a distance it closely resembles a hen- 

 harrier, and it also readily attacks young, sick, and 

 wounded birds ; all others know how little they 

 have to fear from it. When it appears unexpectedly, 

 sweeping over a hedge or grove with a rapid flight, 

 it is sometimes mistaken for a more dangerous 

 species ; there is then a little flutter of alarm, some 

 birds springing into the air, but in two or three 

 seconds of time they discover their mistake, and 

 settle down quietly again, taking no further notice 

 of the despised carrion-eater. On the other hand, 

 I have frequently mistaken a harrier (Circus cinereus, 

 in the brown state of plumage) for a chimango, and 

 have only discovered my mistake by seeing the com- 

 motion among the small birds. The harrier I have 

 mentioned, also the C. macropterus, feed partly on 

 small birds, which they flush from the ground and 

 strike down with their claws. When the harrier 

 appears moving along with a loitering flight near 

 the surface, it is everywhere attended by a little 

 whirlwind of alarm, small birds screaming or chirp- 

 ing excitedly and diving into the grass or bushes ; 

 but the alarm does not spread far, and subsides as 

 soon as the hawk has passed on its way. Buzzards 

 (Buteo and Urubitinga) are much more feared, and 

 create a more widespread alarm, and they are 

 certainly more destructive to birds than harriers. 

 Another curious instance is that of the sociable 



