BIRDS AND THEIR RELATIONS TO MAN 3 



devised a machine which under his control can do laboriously 

 and at great risk what the bird does naturally and easily. To 

 birds man is indebted for his first lessons in navigating the 

 water as well as for his ideas about airships. 



Voices of birds. With few exceptions the different kinds of 

 animals have natural languages through which individuals of 

 the same species can to some extent hold communication with 

 each other, and which are partly intelligible to other creatures. 

 In all mammals except man, and in most birds, the range of 

 expression is very limited and the sound of the voice is dis- 

 agreeable ; but a great many species of birds have very pleasing 

 notes, many have very beautiful natural songs, and some readily 

 learn the songs of other species. Man learned melody from 

 the song birds. There are also many species of birds that can 

 imitate a great variety of sounds, and even learn to speak words 

 and short sentences. Birds that learn to talk often show intel- 

 ligence in their use of words. This is the more remarkable be- 

 cause the intelligence of birds is not of a high order, but is 

 distinctly inferior to that of the common domesticated mammals. 



Social relations of birds. In aerial birds (except the cuckoos) 

 the male and female pair, build a nest, and both take part 

 in the incubation of the eggs and the feeding of the young. 

 Usually a pair once mated remain mated for life and are very 

 devoted to each other. In wild land birds the pairing habit is 

 not of advantage to a species, but still the tendency to single 

 matings is very strong. When land and water birds are domes- 

 ticated man tries to break them of this habit because the males 

 produce no eggs and he prefers to eat them while they are 

 young and their flesh is tender. But, as will appear in detail 

 when the different species of birds of this class are described, 

 he does not always succeed in doing this. Even the domestic 

 fowl and duck, in which pairing has been prevented for cen- 

 turies, often show a strong tendency to pair ; and the females 

 with broods of young usually separate from the flock until the 



