126 Thayer on Protective Coloration. \j^X\ 



objects manifest themselves to the eye, is effaced at every point, 

 the cancellation being as complete at one point as another, as in 

 Fig. C of the diagram, and the spectator seems to see right 

 through the space really occupied by an opaque animal. 



Fig. i of a Ruffed Grouse shows this arrangement of color and 

 light. This bird belongs to the class in which the arrangement is 

 found in its simplest form, the color making a complete gradation 

 from brown above to silvery white beneath, and conforming to 

 every slightest modelling ; for instance, it grows light under the 

 shelving eyebrow, and darker again on the projecting cheek. 



When he stands alive on the ground, as in Fig. 2, his oblitera- 

 tion by the effect of the top light is obvious. 



Writers say " he is so nearly like the color of his surroundings 

 that you cannot see him." Fig. 3 is to show that they ascribe 

 the concealment to the wrong cause. I merely took the bird 

 shown in Fig. 2, and accurately tinted his under parts with brown 

 to match his back, and in less degree tinted his sides, till I had 

 reduced him to uniformity of color all over; but I did not, of 

 course, change his upper surfaces at all. In short, I extended 

 his ' protective ' colors all over him. 



Now observe the effect on replacing him in a life-like position. 

 He is completely unmasked. The reader has but to compare 

 the distance at which he can distinguish a bird in No. 2 and in 

 No. 3 respectively, to see whether simple ' protective coloration,' 

 as ordinarily defined, is the true cause of this concealment, or 

 whether this compound gradation of color and light is the true 

 cause. 



Fig. 4 and Fig. 5 show that his colors are powerless to conceal 

 him in any position except the upright one which he holds when 

 alive, and Figs. 6 and 7 do the same for the Woodcock. 



In Figs. 5 and 6, notwithstanding the fact that we have even the 

 strongest ' protective ' colors towards us, the bird is by no means 

 concealed. 



The Woodcock series corresponds to that of the Ruffed Grouse. 

 Fig. 8 shows a female on her nest, very difficult to find. In Fig. 9 

 the bird has been treated exactly as I treated the Ruffed Grouse 

 in Fig. 3. Observe that she is essentially more conspicuous, 

 though not a feather of her upper parts has been artificially painted. 



