INTRODUCTION. 



EVERYONE knows what a bird is ! Whether it be an 

 Ostrich, a Canary or a Barn-yard Fowl we immediately 

 distinguish it as a bird by its covering of feathers, if by 

 nothing else. Birds form a separate " class " of the 

 Vertebrate Sub-kingdom of animals, and agree with the 

 mammals in possessing a four-chambered heart and hot 

 blood. In addition to their covering of feathers they are 

 characterised by the fact that they produce their young 

 from eggs laid by the female (a point that is, however, 

 shared by most reptiles, and by several of the lower 

 mammals), and that the forelimbs, in the shape of wings, 

 are usually adapted for flight. Their bones are moreover 

 usually rendered lighter by being partly hollow and filled 

 with air, in addition they have a number of " air-sacs " 

 within their bodies, which is also of assistance in flight. 

 Lastly, all modern birds are toothless, at least as far as 

 actual or true teeth are concerned. 



The majority of the members of the avian world are 

 notable for their graceful form, and their power of being 

 able to transport themselves through space with ease 

 and rapidity, a fact which enables them to travel enor- 

 mous distances. 



Birds are, comparatively speaking, perhaps better known 

 and have attracted more notice than any other group of 

 animals, the beauty of the plumage of many birds, the 

 gift of sweet song with which others are endowed, their 



