192 



THE WORLD OF ANIMAL LIFE 



other kind of animal has. These are placed very close to the body, 

 and are so smooth on the surface as not to impede the bird in 

 flight. The tail-feathers are used for steering, like the rudder 

 of a boat. 



The plumage of birds, especially in the warmer climes, is often 

 very beautiful. That of the cock bird is usually more brilliant 

 than that of the hen. In many cases it is difficult at first to believe 

 that the two birds are of the same species. 



Once every year birds "moult", that is, shed their feathers. 

 During this period they are very dull; but as new feathers quickly 

 grow in place of the old ones, they are soon as lively as ever again. 

 The eggs of birds exhibit great variety in shape and colouring, 

 and the latter is often very beautiful. Birds that build in holes 

 often lay white eggs, or nearly white — white with a few brown 



specks at the broad end. Those which 

 nest on the ground as a rule lay eggs 

 which closely resemble their surroundings 

 in colour, and are thus often difficult to 

 find. 



In the case of the larger birds the 

 young are hatched almost fully fledged, 

 and are at once able to run about. The 

 eggs are therefore generally laid in a very 

 rough - and - ready nest, and sometimes 

 simply on the bare ground. But in the 

 case of the small birds the young are pro- 

 duced in a more helpless condition, and 

 have to be carefully protected until they 

 are able to fly. 



Birds show wonderful ingenuity in the 

 building of their nests. Some build with 

 mud, others with hay, straw, or sticks; 

 others again weave moss, horse-hair, and 

 wool into a very cosy nest; and some even stitch large leaves 

 together. All succeed in making very snug homes for the young 

 birds, usually well hidden from the eyes of a possible enemy. 



It may seem strange that a bird does not fall off a tree when 



u, Section of bone of mammal 

 showing marrow; b, section of 

 bone of bird. 



