The Audubon Societies 65 



warmth of the body and in preserving the bird's life in case of hard times, when 

 food is scanty. 



Let us briefly sum up in conclusion the few facts we ha\'e learned about I he 

 plan of a bird: 



1. A bird is a vertebrate and is built on a vertebrate plan. I'he presence of a back- 

 bone, a closed blood-system, a t\vo-la_\ered skin, and ne\-er more than four limbs. ;ire 

 some of the things which make a bird a vertebrate. 



2. .V bird has a peculiar covering of feathers, whkli distinguisiu-s it from all ollur 

 ireatures. 



j. .\ bird is not onh' ca[iablc of llight, but possesses the most i)crfect known mrcluiTi 

 ism of flight. 



4. The wings of a bird are its most important de\ices of flight, l)ut these (lejjend 

 for their rigidity upon their attachment to a firm breastbone by means of large muscles; 

 for their lightness upon hollow bones and a system of air-sacs, and also upon a feather 

 covering; and, for their flexibility, upon joints that move only in certain desired direc- 

 tions, as well as upon the close but pliable feathers which they support. 



5. In addition to wings, a bird must have some means of steering its course and of 

 kee|)ing its equilibrium in flight. The neck and tail, and in some instances the feet, 

 and certain movements of the wings, assist it in attaining a perfect and easy flight. 



0. Not all birds live on the wing, and need therefore to be adapted to finding their 

 food on the ground or in the water. The hind-limbs, or legs, of a bird are variously 

 modified to meet this need; and, whereas the wings of different kinds of birds are very 

 similar, their legs and feet are often extremely dissimilar. 



7. The Loon belongs to a group of birds known as divers. It is remarkable for the 

 peculiar position of its hind-limbs, which are used more as oars under water than as 

 legs on land. Diving birds have no equal on water, but they are quite helpless on land, 

 and fly rather jioorly, or not at all. in air. 



SUGGESTIONS 



Where are the claws of a bird found? Did you ever know of a bird that had claws 

 on its wings? 



How niuch heavier do you think a bird is than the air in which it flies? 



Can a bird fall down out of the air? 



Why cannot a bird move its wings around in a rotary way as we do our arms? Mow 

 does the Penguin use its wings? 



Draw the Loon, and make enlarged drawings of its bill and feet. 



Draw the Grebe and make enlarged drawings of its bill and feel. Compare these 

 drawings. 



Learn to write correctly the following words: 



vertebrate \ertebra (plural, adaptation rigidity 



flexibility vertebr:ej equilibrium structure 



cassowary Penguin stability conserve 

 preser\e 



What is the derivation of Loon? Look up Penguin, Ostrich, and Kiwi in Newton's 

 Dictionary of Birds, or elsewhere. — A H. W. 



