235 NATURAL HISTORY. 



to be followed, if lie read the lesson aright. Birds teach us many things perseverance, fidelity, 

 parental affection, thrift, cleanliness, and many other domestic virtues, which are to be seen carried out 

 in their life in the greatest perfection. In the following pages the birds will be passed in review, and 

 the habits of some of the most striking and important forms will be detailed. But, although every 

 species and genus cannot be noticed here, it is necessary to assure the student that in every 

 country even in England, where so much has been done for Ornithology he will find an ample 

 reward in the- study of all birds ; and that even the commonest species cannot be neglected, 

 for there is always something new to learn and to record in their life-history. To quote 

 Dr. A. E. Brehm, one of the most accomplished observers of nature, who, carefully trained by his 

 father, a true naturalist also, has studied the feathered tribes in many climes : 



" He who is only half at home with nature on this earth of ours will be able to approxi- 

 mately to appreciate the feelings with which the naturalist wanders and travels from place to 

 place : wherever he may be he finds friendly forms. For years he has silently watched the interior 

 economy and household arrangements of animated nature, and yet he has not seen all ; and on this 

 account he is never in want of employment. Eveiy bird is a personal friend : the old ones he knows 

 almost as well as he knows himself, and the new ones must be studied. How much more is there yet 

 to observe ! Rich as he may be in experiences, every fresh ramble brings him fresh mental treasure. 

 The relations existing between him and the bird become each day more and more intimate ; he knows 

 the lives and habits of each : when each arrives, or takes its departure : where is its abode : how it is 

 made : when it is occupied by a happy troop of nestlings : when deserted. The naturalist knows his 

 friends by their notes, flight, and bearing. In his eye the bird never ceases to exist : alive or dead it 

 is always interesting in his eyes, for in either case the bird is associated with a poesy of feeling in 

 creative nature which he would put into words. Every new bird raises his spirits a step higher ; every 

 fresh discovery is a step onward in the knowledge of the ways and means of all things. He is indebted 

 to his friends for many a happy hour ; their lives are a pattern worthy of imitation."* 



Here, then, we may ask What is a bird ] How can a bird be told from all other Vertebrate 

 animals 1 The chief character which distinguishes the class of birds is undoubtedly the clothing of the 

 body with feathers. Other characters they also possess, but not exclusively. For instance, they have the 

 power of flight developed in the greatest degree : but there are some birds, such as the Apteryx, the 

 Ostrich, and the Cassowary, which cannot fly at all ; while, on the other hand, there are flying mammals, 

 such as Bats, Flying Squirrels, and there are flying reptiles, which can progress through the air by 

 means of flight. Again, birds lay the eggs from which they produce their young ; but so do many 

 reptiles and fish : so that this cannot be considered a prerogative of the class of birds. Their bill is 

 hard and sheathed in horn; but so is that of the Duck-billed Platypus (page 231), an animal belonging 

 to the Monotreme Mammals ; and Turtles also have beaks. Most, but not all, birds build nests ; 

 and in this they stand almost alone among the higher animals; but nest-building propensities are 

 developed in many of the Mammalia in the Lemurs and Mice, for instance while it cannot be 

 assigned as a habit peculiar to birds, as the wonderful nests made by some fish conclusively prove. 



All birds, whether they fly or not, are clothed with feathers, and this distinguishes the class Aves 

 in the existing state of nature. The majority are specially adapted for flight : and as this is 

 undoubtedly the most vigorous form of locomotion, the greatest muscular efforts being required to 

 raise and sustain a body above the ground and to propel it rapidly through the air, a large 

 development of muscular energy is necessary. The great strain on the circulation of the blood 

 is met by a heart not only as complete as in the Mammalia, but with stronger and a peculiar 

 valvular mechanism for propelling that fluid vigorously through the body. Moreover, in addition 

 to their lungs, birds possess a singular provision of air-receptacles within the body, and these 

 are connected with a series of cavities, also filled with air, which occupy the interior of most of the 

 bones. These cavities serve not only to give lightness to the bird's body, but they also assist the lungs 

 in aerating the blood, so that birds may be said to enjoy a double respiration. As birds exceed mam- 

 mals in the activity of their breathing and circulatory system, so also they possess a higher degree of 

 animal heat, their temperature ranging from 106 to 112 Fahr. This high temperature, which exceeds 



* Dr. Brehm : " Bird-life," pp. 503, 504. 



