COLORATION 147 



is never a survival factor which operates in natural selection, 

 or else so very rarely that it can in practice be disregarded. 



In very many cases where the young are concealingly 

 colored, the adults have a different and relatively a revealing 

 coloration; and in very many cases where the female is 

 concealingly colored, the male has a revealing coloration. 

 This means, in all probability, that the evolution has been 

 from a concealingly colored form to a form in which both 

 sexes when adults, or else the adult males, are revealingly 

 colored ; there could be no more striking proof of the un- 

 importance of coloration as a survival factor, and of the fact 

 that it is quite impossible that in most cases among the 

 higher vertebrates their present adult coloration can have 

 been developed by natural selection. Evidently in the 

 varied lives led by most adult birds and mammals the im- 

 portance of the animal's senses, and its truculence, wari- 

 ness, prowess, speed, agility, and ability to take advan- 

 tage of cover so far outweigh coloration that the latter 

 becomes negligible as a survival factor. In some cases, 

 however, it is a survival factor; this is especially true as 

 regards many young birds and brooding mothers, which of 

 necessity must trust to immobility for escape at critical 

 periods; but it is also true of old birds of both sexes in 

 various species of night-hawks, grouse, woodcock, etc. 



Spotted fawns and young tapirs, and striped and spotted 

 chicks of various birds, probably indicate ancestors of such 

 coloration in a very remote past, although there is no in- 

 dication of a change of habitat. On the supposition that 

 these striped and spotted patterns have a concealing value, 

 this may mean that these ancestors were more immobile 

 than their present-day descendants; it may mean that the 



