ABOUT BIRDS IN GENERAL. 



Birds as a class occupy a place between mammals 

 and reptiles, but nearer reptiles. Unlike and far apart 

 as birds and snakes now are, fossil remains prove 

 that they have a common ancestry, that both are de- 

 scended from what is called reptilian stock, and have 

 arrived at their present forms by a long and wonderful 

 process of evolution. A character still common to 

 both is egg-laying, although reptiles, with few excep- 

 tions, do not incubate. 



Birds, standing between mammals and reptiles, have 

 no marked peculiarities of structure not found in one 

 or the other class, except that of body-covering; they, 

 and they only, are clothed in feathers. This ideal 

 clothing is light, warm, and non-conducting, thus 

 permitting a high temperature to be maintained. The 

 heat of a bird's body is about no degrees, against 98 

 degrees in mammals and 40 degrees in reptiles. 



Birds are said to be protectively colored when the 

 tints of their plumage harmonize with their haunts, 

 making them inconspicuous to their enemies. The 

 brown, striped Sparrows, Quail, and Whip-poor-will 

 are good examples of protective coloration in birds 

 that are much on the ground, and Vireos and female 

 Tanagers of those that live in trees. 



Birds do not perspire. They have an oil-gland at 

 the base of the tail from which they press out a drop 

 of oil with the beak, and dress or " preen " their 

 feathers. This gland is specially developed in water- 



