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 

 maiinnals and birds which normally owe their safety to the fact 

 that their coloration matches their surroundings, crouch Hat 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 ce;ises 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 innnense 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 " obliteration " of them as they 

 flee. He actually continues that " when these beasts flee at night 

 before terrestrial enemies, their brightly displayed, sky-lit white 



