12 OUR DOMESTIC BIRDS 



were grown in succession, the third and last making the adult 

 plumage of the bird. This coat remains until the following 

 summer or fall, when it is molted and replaced by a new one. 



Flight. The habit of flying is objectionable in domestic birds 

 because it makes them more difficult to control. It has no di- 

 rect use except in pigeons kept for flying. There is, however, 

 a very important connection between development for flying 

 and the value of birds for the table. The muscles of the wings 

 furnish the greater part of the edible meat of most birds. The 

 most desirable birds for food purposes are those which have the 

 wing muscles well developed, yet not quite strong enough to 

 enable them to fly easily. In such birds the breast meat re- 

 mains comparatively soft through life, while in birds that fly 

 well it becomes hard in a very short time. That is why the 

 breast meat of the pigeon is relatively tougher in an old bird 

 than the breast meat of a fowl or turkey. 



The balance between capacity for flight and neglect to use it, 

 which is desired in birds grown for the table, is secured by 

 giving them opportunity to exercise their wings moderately but 

 not for progressive practice in flying, which would soon enable 

 them to fly easily over the fences used to confine them. To regu- 

 late such exercise the perches for birds that roost are made 

 low, or in an ascending series in which each perch after the 

 first is reached from the one below it, while fences are made so 

 much higher than the distance the bird is accustomed to fly 

 that the failures of its first efforts to go over them discourage 

 it. Ducks and geese, which do not roost, flap their wings a 

 great deal, and if they have room often exercise them by half 

 running and half flying along the ground. 



Mechanism of the wing. In its structure and in the muscular 

 power that moves it, the wing of a bird is a wonderful piece of 

 mechanism. A bird in flying strikes the air with its wings so 

 rapidly that the movements cannot be accurately counted. The 

 heron, which is a slow-flying bird, makes from one hundred 



