COLORATION 145 



We must also remember those animals which, although 

 not concealingly colored, yet crouch and hide precisely as if 

 they were; the steinbok, for instance, and the white- tail 

 deer with its red coat showing against the green foliage of 

 spring and summer, crouch motionless and take the utmost 

 advantage of cover. It is probable that the race experi- 

 ence through immemorial ages has instilled into the major- 

 ity of the higher vertebrates the prime value as survival 

 factors of immobility, and of taking advantage of cover, in 

 order to escape observation. When other and more power- 

 ful factors intervene these two may, of course, lose all im- 

 portance and be abandoned; many animals which have not 

 developed concealing coloration, such as adult prongbuck 

 and white goat, wildebeest and zebra, never seek to es- 

 cape observation, whether by immobility or by taking ad- 

 vantage of cover. Nevertheless, other animals which have 

 not developed a genuine concealing coloration, such as the 

 bongo, and the wapiti with its pale, advertising rump, do 

 crouch behind cover and seek by immobility to escape ob- 

 servation. Yet other animals have developed a concealing 

 coloration and take advantage of it. 



As regards the immense majority of birds and mammals, 

 habit and cover remain of such overwhelming importance 

 that coloration is either not a survival factor at all or else 

 becomes such — that is, becomes a factor telling against 

 survival — only if very, very striking hues are developed; 

 and probably only rarely under these circumstances. To 

 mice and shrews, immobility, night, and the actual physical 

 screen of earth, grass, or snow are all-important; the colora- 

 tion may be of any one of many tints or patterns without 

 producing the smallest survival effect. This is equally true 



