CHAPTER V 



THE GENERAL HABITS AND FUNCTIONS OF BIRDS 



The flight of birds Flightless birds The fitness of birds 

 for an aerial existence Various modes of flight Gliding 

 flight : how performed Flight by active strokes of the 

 wings: how performed The movement of the wings 

 Soaring or sailing flight : how performed Terrestrial 

 and aquatic motion of birds Birds unable to progress 

 upon the ground Running, walking, and hopping 

 movements Progress in water The food of birds 

 Modifications of the bill Common to various distantly 

 related groups Social, gregarious, or solitary instincts 

 of birds Mimicry in birds Protective colours and 

 resemblances of birds Forest birds Desert birds 

 Marsh and swamp birds Moorland and mountain 

 birds Arctic birds Variation in birds Of external 

 structure and colour Dimorphism in birds Sexual 

 dimorphism Dimorphism independent of sex 

 Structural dimorphism. 



WE have now reached that stage in the story of 

 the Birds where it becomes necessary to devote 

 a chapter to their general Habits and Functions. 

 We have traced their history from their early 

 origin down to the present era, and briefly 

 sketched their general characteristics, anatomical 

 and otherwise ; we have grouped all living birds 



