PROTECTIVE COLORATION 
507 
whole thesis is that such is the case. But as a matter of fact, the 
great majority of these mammals, when they seek to escape 
observation, crouch on the ground, and in that posture the light 
belly escapes observation, and the animal’s colour pattern loses 
very much of, and sometimes all of, the “ full obliterative shading 
of surface colours ” of which Mr. Thayer speaks. Moreover, when 
crouched down in seeking to escape observation, the foes of the 
animal are most apt to see it from above, not from below or from 
one side. This is also the case with carnivorous animals which 
seek to escape the observation of their prey. The cougar crouches 
when lying in wait or stalking, so that it is precisely when it is 
seeking to escape observation that its lighter-coloured under parts 
are obscured, and the supposed benefit of the “ obliterative shading 
pattern ” lost. I do not intend without qualification to take 
ground one way or the other on this general question ; but it is 
certainly true that any such sweeping statement as that quoted 
above by Mr. Thayer is as yet entirely unproved. I have no doubt 
that in most cases animals whose colours harmonize with their 
environment, and which also seek to escape observation by remain¬ 
ing motionless when they think there is danger, are very materially 
helped by their concealing coloration ; but when this concealment 
is said to be due to the obliterative shading as described by 
Mr. Thayer, it is certainly worth while considering the fact that 
the so-called obliterative pattern is least shown, or is not shown at 
all, at the only time when the animal seeks to escape observation, 
or succeeds in escaping observation—that is, when it crouches 
motionless, or skulks slowly, with the conscious aim of not being 
seen. No colour scheme whatever is of much avail to animals 
when they move, unless the movement is very slow and cautious; 
rats, mice, gophers, rabbits, shrews, and the enormous majority of 
mammals which are coloured in this fashion are not helped by their 
special coloration pattern at all when they are in motion. Against 
birds of prey they are practically never helped by the counter¬ 
shading, but merely by the general coloration and by absence of 
movement. Their chief destroyers among mammals—such as 
weasels, for instance—hunt them almost or altogether purely by 
scent, and though the final pounce is usually guided by sight, it is 
made from a distance so small that, as far as we can tell by 
observation, the “ counter-shading ” is useless as a protection. In 
fact, while the general shading of these small mammals’ coats may 
very probably protect them from certain foes, it is as yet an open 
question as to just how far they are helped (and indeed in very 
many cases whether they really are helped to any appreciable 
extent) by what Mr. Thayer lays such special stress upon as being 
“ full obliterative shading (counter-shading) of surface colouring.” 
Certainly many of the markings of mammals, just as is the case 
