HABITS OF BIRDS 



759 



so that they have hardly heard the voices of their kind, may utter the 

 characteristic note of the species, but they sing the song imperfectly. 

 Many birds, apart from those who have been educated, have 



Fig. 456. — Wings coming down, — From Marey. 



" words," expressing pleasure, pain, sense of danger, presence of food, 

 and the like. But there is a difference between uttering words and 

 having a language, which implies the expression of a judgment. 



Fig. 457. 



-Wings completely depressed. — From Marey, 



Courtship. — Birds usually pair in the springtime, but there are 

 many exceptions. A few, e.g. some of the birds of prey, live alone 

 except at the pairing time ; others, notably the doves, always live 

 together in pairs ; many, such as rooks, parrots, and cranes, are 



