152 Idle Days in Patagonia. 
body in birds is less solid; it is filled with air in the 
bones and feathers, and acts differently as a sound- 
ing board; furthermore, the extremely distensible 
esophagus, although it has no connection with the 
trachea, is puffed out with swallowed air when the 
bird emits its notes, and this air, both when re- 
tained and when released, in some way affects the 
voice. Then, again, the bird sings or calls, as a 
rule, from a greater elevation, and does not sit 
squat, like a toad, on his perch, but being lifted 
above it on his slender legs, the sounds he emits 
acquire a greater resonance. 
There are bird sounds which may be, and often 
are, likened to other sounds ; to bells, to the clang- 
ing produced by blows on an anvil, and to various 
other metallic noises; and to strokes on tightly- 
drawn metal strings; also to the more or less 
musical sounds we are able to draw from wood and 
bone, and from vessels of glass by striking them or 
drawing the moistened finger-tips along their rims. 
There are also sounds resembling those that are 
uttered by mammalians, as bellowings, lowings, 
bleatings, neighings, barkings, and yelpings. Others 
simulate the sounds of various musical instruments, 
and human vocal sounds, as of talking, humming a 
tune, whistling, laughing, moaning, sneezing, cough- 
ing, and so on. But in all these, or in a very large 
majority, there is an airy resonant quality which 
tells you, even in a deep wood, in the midst of an 
unfamiliar fauna, that the new and strange sound 
is uttered by a bird. The clanging anvil is in the 
