102 THE BOOK OF NATURE STUDY 



leafy branches more or less conceal them from wandering egg- 

 stealing birds above. Other pigeons, however, lay their eggs 

 in caves, as the rock-pigeon ; or in burrows, as the stock-dove ; 

 so that we may perhaps assume the custom of building of nests 

 in trees* is a comparatively recent custom. 



NestKng Birds. Few themes in ornithology can be made 

 more interesting or more instructive than the subject of nestling 

 birds. 



These can be divided into two classes those which on hatching 

 are blind, naked and helpless, and those which are thickly clothed 

 with down and able to run about from the moment they leave 

 the shell. The latter represents the more ancient condition. 

 Young chickens, and young ducks, present two distinct types of 

 such active nestlings ; and they differ strikingly in one impor- 

 tant particular to wit, the methods by which they escape 

 their enemies. Young chickens to-day, in this respect, differ 

 in no way from their wild relatives the jungle-fowl, or from 

 young pheasants, partridges and grouse. In all these it is 

 necessary that the power of flight should be acquired at the 

 earliest possible moment, and consequently the development of 

 the wings is pushed forward with extraordinary rapidity, so 

 much so that in many species the young can fly at eighteen hours 

 old, and long before the down feathers of the rest of the body 

 are lost. Young ducks, like the young of wild geese and swans, 

 on the other hand, seek safety by swimming, and consequently 

 the wings develop exceedingly slowly, so much so that the body 

 is feathered long before the wings acquire their quills, so that 

 when nearly full grown they are to all intents and purposes 

 wingless. 



Another feature of young chickens should be noticed. In 

 some breeds the nestlings are striped, a broad dark band down 

 the middle of the back being especially conspicuous. The young 

 of all wild game-birds, young grebes, and the young of the ostrich 

 tribe are all striped ; the stripes in the grebes and ostriches being 

 more numerous than in the species just referred to. These mark- 

 ings, like the stripes of zebras, conspicuous though they appear 

 when in a museum, or in captive birds, have really a protective 



