Vol. XXIX1 



9112 



J Allen, The Concealing Coloration Question. 505 



cealing properties of the deer's white flag, it may still be that this 

 concealment is only incidental, for I suspect that in the deer's case, 

 as in the case of the Spotted Sandpipers before referred to, the 

 white markings may still serve the purpose of directing the deer's 

 companions. The deer's head is carried above the level of his 

 tail or perhaps on a level with the uplifted tail, so that normally 

 the flag would appear to another deer against a very different back- 

 ground from that which the panther or wolf would see it against; 

 that is, of course, when the deer in front is not bounding high in 

 the air, but the flag is thrown up first while the deer is still on the 

 ground and may even be carried that way at a slow canter, and 

 then, too, the following deer is also bounding and so could often 

 catch the white gleam from the deer in front as its tail relieved 

 against the foliage or the ground. I merely throw this out as a 

 suggestion of a possible reconciliation of the theory of directive 

 markings with that of the inherent concealing power of all markings. 

 There is much to be learned about these things, and common sense 

 plus experiment and thought will be a safer tutor than unaided 

 common sense. I will add that the last time I saw the deer throw 

 up their white flags, the white, being seen against an evenly clouded 

 sky, was inconspicuous. Of course, it was visible, because this 

 was in the daylight and the deer were in plain sight, but it de- 

 tracted from, rather than added to, the conspicuousness of the deer. 

 Sexual selection is another theory that seems to me not at all 

 incompatible with Thayer's main contention. Bright colors, as 

 he shows, or endeavors to show, are not necessarily revealing, but 

 that is not saying that they may not be attractive to the opposite 

 sex. It seems to me that many of the bright and beautiful colors 

 and markings in the plumage of birds may be produced by sexual 

 selection but afterwards acted upon by natural selection. Sexual 

 selection, that is, may supply a short cut to the production of con- 

 cealing colors when they happen to be bright ones; or, to put it in 

 another way, natural selection may set bounds (I borrow the expres- 

 sion from Roosevelt) to the colorations produced by sexual selec- 

 tion. It seems to me that Mr. Thayer is unnecessarily shy of 

 sexual selection. I cannot see that it tells against his theories 

 at all, and it is a reasonable explanation of the primary, or perhaps 

 I should say the secondary, cause of many forms of coloration. 



