SELF-COLOURS AND STRIPES 137 



they have down at all, have it self-coloured, usually 

 black, white, grey, or buff. There is an interesting 

 exception, however, in the case of the Osprey 

 among birds of prey, whose helpless young have 

 variegated down, although in such birds the down 

 is generally white. 



Among the birds with active young, too, there are 

 conversely groups or species which have se^coloured 

 down ; young Rails are black, young Cranes tawny, 

 or, in the case of the splendid Stanley Crane of 

 South Africa (Tetrapteryx paradisea), grey, and 

 cygnets grey or white. And among the Game-birds, 

 which so generally have striped down, that of the 

 young chicks of the desert Seesee Partridge (Ammo- 

 perdix bonbami) is plain buff; and so is that of 

 Hemprich's Gull (Larus bemprichi), which breeds 

 on the scorching rocks of the Red Sea. 



Taken into consideration with the fact that the 

 young of the common Fowl, which are naturally 

 strongly striped, as may be seen in the young of 

 such breeds as the Brown Leghorn, which are 

 coloured like the original Jungle-Fowl, generally 

 appear in buff, black, yellow, or grey down, the 

 conclusion seems at first irresistible that in the case 

 of patterned chicks the pattern is necessary for pro- 

 tection, and that where security does not depend 

 on coloration, it tends to disappear. Thus, the 

 Cranes and Swans are strong birds and can protect 

 their young and the Rails are clever skulkers and 

 never go far from cover, so that the young of these 

 may have lost the pattern just as nestling birds 



