PROTECTIVE COLORATION 
503 
coloration for defensive purposes or offensive purposes.’’ So far as 
Mr. Thayer’s book or similar books confine themselves to pointing 
out cases of this kind, and to working on hypotheses where the 
facts are supplied by such cases, they do a real service. But it is 
wholly different when the theory is pushed to fantastic extremes, 
as by those who seek to make the coloration of big game animals 
such as zebras, giraffes, hartebeests, and the like, protective. I 
very gravely doubt whether some of the smaller mammals and 
birds to which Mr. Thayer refers really bear out his theory at all. 
He has, for instance, a picture of blue jays by snow and blue 
shadow, which is designed to show how closely the blue jay agrees 
with its surroundings (I would be uncertain from the picture 
whether it is really blue water or a blue shadow). Now, it is a 
simple physical impossibility that the brilliant and striking 
coloration of the blue jay can be protective both in the bare 
woods when snow is on the ground and in the thick leafy woods 
of midsummer. Countless such instances could be given. Mr. 
Thayer insists, as vital to his theory, that partridges and other 
protectively coloured animals owe their safety, not at all to being 
inconspicuously coloured—that is, to being coloured like their 
surroundings—but to their counter-shading, to their being coloured 
dark above and light below. But, as a matter of fact, most small 
mammals and birds which normally owe their safety to the fact 
that their coloration matches their surroundings, crouch flat when¬ 
ever they seek to escape observation; and when thus crouched flat, 
the counter-shading on which Mr. Thayer lays such stress almost, 
or completely, disappears. The counter-shading ceases to be of 
any use in concealing or protecting the animal at the precise 
moment when it trusts to its coloration for concealment. Small 
rodents and small dull-coloured ground birds are normally in fear 
of foes which must see them from above at the critical moment if 
they see them at all; and from above no such shading is visible. 
This is true of almost all the small birds in question, and of the 
little mice and rats and shrews, and it completely upsets Mr. 
Thayer’s theory as regards an immense proportion of the animals 
to which he applies it; most species of mice, for example, which 
he insists owe their safety to counter-shading, live under conditions 
which make this counter-shading of practically no consequence 
whatever in saving them from their foes. The nearly uniform 
coloured mice and shrews are exactly as difficult to see as the 
others. 
Again, take what Mr. Thayer says of hares and prongbucks. 
Mr. Thayer insists that the white tails and rumps of deer, 
antelopes, hares, etc., help them by 44 obliteration ” of them as they 
flee. He actually continues that 44 when these beasts flee at night 
before terrestrial enemies, their brightly displayed, sky-lit white 
