496 APPENDIX E 



effect of the white rump is minimized, as is alsr the effect of the "counter- 

 shading"; for the light-colored under parts are pressed against the earth, 

 and the little kid lies motionless, trusting to escape observation owing 

 to absence of movement, helped by the unbroken color surface which is 

 exposed to view. If the adult prongbucks really ever gained any bene- 

 fit by any "protective" quality in their coloration, they would certainly 

 act like the kids, and crouch motionless. In reality the adult prong- 

 buck never seeks to escape observation, never trusts in any way to the 

 concealing or protective power of any part of its coloration, and is not bene- 

 fited in the slightest degree by this supposed, but in reality entirely non- 

 existent, concealing, or protective power. The white rump practically never 

 has any obliterative or concealing function; on the contrary, in the great 

 majority of instances, it acts as an advertisment to all outside creatures of 

 the prongbuck's existence. Probably it is an example of what is known 

 as directive coloration, of coloration used for purposes of advertisement 

 or communication with the animal's followers. But however this may be, 

 it is certain that there is not the smallest justification for Mr. Thayer's 

 theory so far as the prongbuck is concerned. 



It is practically the same as regards the rabbit or the hare. Any one 

 who has ever been in the woods must know, or certainly ought to know, that 

 when hares are sitting still and trying to escape observation, they crouch 

 flat, so that the white of the tail and rump is almost concealed, as well 

 as the white of the under parts, while the effect of the counter-shading 

 almost or entirely vanishes. No terrestrial foe of the hare would ever 

 see the white rump against the sky-line unless the animal was in rapid 

 motion (and parenthetically I may observe that even then it would only see 

 the rump against the sky-line in an infinitesimally small number of cases). 

 Of course as soon as the animal is in motion it is conspicuous to even the 

 most dull-sighted beast of prey; and Mr. Thayer's idea that the white 

 rear patch may mislead a foe as it jumps upon it is mere supposition, un- 

 sustained by any proof, and contrary to all the facts that I have observed. 

 Civilized man, who is much more dull-sighted than most wild things, can 

 always see a rabbit when it runs because its white is then so very con- 

 spicuous. Here again I do not think there is the slightest value in Mr. 

 Thayer's theory. The white rump is certainly not a protective or ob- 

 literative marking; it is probably a directive or advertisement marking. 



The Virginia deer, utterly unlike the prongbuck, does often seek to 

 evade observation by lying close, or skulking. When it lies close it lies 



