CHAPTER II. 

 Birds. 



THE one chief characteristic by which birds are distinguished from all other 

 animals is that they alone have their bodies covered with feathers. These are 

 of two kinds the " down " feathers and the " contour " feathers the latter 

 arranged on certain definite parts of the body so methodically that they can 

 be identified, practically in all cases, hi the same place on every species. A 

 glance at the diagram (page 50) will show the arrangement of the chief feathers 

 and groups of feathers better than any description. 



Birds are warmer blooded than mammals, their temperature being 106 to 

 108 F. This is due, in part, to the more extended development of their 

 breathing apparatus, as well as to the superior protection of their feathers. 

 In addition to their lungs, birds have certain air spaces in different parts of 

 their bodies communicating with them, so that they can make use of more 

 oxygen than mammals, and thus produce greater heat. In addition, some 

 of their bones are hollow, and contain air. These characteristics make the 

 bird very light in weight, and so specially adapted for flying. 



Note also that, instead of teeth, birds possess a gizzard, which serves as 

 the masticating organ. This is in reality a mill in which the food is ground 

 up, and consists of two strong and muscular portions covered with a tough 

 skin. Within are always some small stones or pieces of grit, which are in a 

 constant state of movement as the two parts of the gizzard rub together. 



It is worth while to observe the skeleton of a bird, with its special points 

 of difference from our own the many bones in the neck, which enable the 

 bird to revolve the head with far greater freedom ; the extraordinary breast- 

 bone with its keel, to which the powerful wing muscles are attached ; and the 

 fewness of the ribs. 



I am not hi favour of " collecting " eggs, unless it is done with a purely 

 scientific aim. The student will do far better to observe birds and their 

 nests than to take their clutches. Many of our British birds are in danger of 

 extinction at the hands of would-be collectors. What is to be said, for in- 

 stance, of one who told me with triumph that in one season he had taken 

 eight nests of kingfishers ! If eggs are taken, for purposes of study and com- 

 parison, it is sufficient to take one from a nest ; the rest number, and general 

 colouring and size can be made a matter of notebook and pencil, and if need 

 be, of camera and lens. There is no necessity whatever for the taking of the 



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