Book News and Reviews 



259 



upon living in the densest cover, or ability 

 to take advantage of comparatively scant 

 cover. A study of the big antelopes that 

 live in the reeds, and of the big and small 

 antelopes that live in the jungle, and of 

 most of the birds of the tree tops, will 

 show that in all these places with very 

 thick cover, or with varied cover, conceal- 

 ing coloration plays little or no part; for 

 the animals that do not possess it thrive 

 as successfully as those that do. 



"(lo) It is easy to understand that ad- 

 vertising and concealing coloration should 

 alike be indifferent to animals that live 

 in such cover as to hide both them and 

 their coloration. But many mammals and 

 birds live absolutely or practically in the 

 open, or under conditions where adver- 

 tising coloration does in fact advertise 

 them at a much greater distance than 

 would be the case if they lacked it; and 

 yet even under these conditions hundreds 

 of species of highly advertising coloration 

 prosper as well as, although apparent^ 

 no better than, those with a concealing 

 coloration. Gulls, Cormorants, Loons, 

 Grebes, Guillemots, Fulmars in the water; 

 Herons, Storks, Ibises, Plover on the 

 plains or the edges of marshes, lakes and 

 rivers; big antelope and zebra on the 

 plains; Blackbirds, Grackles and Bob- 

 olinks in the meadows and pastures ; 

 all illustrate this fact. The numerous 

 species of Bee-eater which I saw in 

 Africa all had an intensely advertising 

 coloration, and lived under conditions 

 which accentuated the advertising qual- 

 ity of the coloration. The topi, with its 

 very bold and inversely countergraded 

 coloration, is no more nor less at home in 

 the places where it dwells than is the 

 countershaded eland, with its much less 

 conspicuous coloration. A male Grants' 

 gazelle, which is countershaded and not 

 very advertisingly colored, is no less and 

 no more at home than the female of the 

 same species, which has an advertising 

 black stripe along the body, or than the 

 smaller Thompson's gazelle, which also 

 has the black stripe, together with the 

 habit of perpetually twitching its tail 

 whenever it is standing up. The Yellow- 



headed Blackbird has an extraordinarily 

 advertising coloration; but I cannot see 

 that it affects the welfare of the species 

 one way or the other. 



"Among certain species of birds, how- 

 ever, there is a contrast in the behavior 

 of those that are advertisingly colored 

 and those that are not. On the plains. 

 Thrashers always skulk and seek cover in 

 which to hide, while Blackbirds, which of 

 course are infinitely more conspicuously 

 colored than the Thrashers, walk and sit 

 boldly in the open. The Meadowlark, 

 which has a highly advertising breast 

 coloration, but a concealing back color- 

 ation, skulks and takes advantage of 

 cover in a way which the Robin never 

 does. On the other hand, there are other 

 cases where birds that are concealingly 

 colored take no advantage of their color- 

 ation, and behave exactly as do their 

 kinsfolks that are advertisingly colored. 

 The Kingbirds, and especially the Scissors- 

 tailed Flycatchers, are very conspicuous, 

 and are good examples of advertising 

 coloration, when in their ordinary sur- 

 roundings. Most of their near kin, the 

 Phoebes, are inconspicuously colored; 

 but neither the Phoebes nor the Wood 

 Pewees seem to take advantage of their 

 coloration in order to try to conceal 

 themselves. Most of the small Flycatch- 

 ers do live in thickets, where their incon- 

 spicuous coloration may be of benefit to 

 them; but the great-crested Flycatcher, 

 which is colored substantially like the 

 Western Kingbird, is unlike the King- 

 bird in its habits, and at least sometimes 

 seeks to take advantage of cover. There 

 are innumerable instances of this kind. 



"(ii) In short, as one might antici- 

 pate, when we deal with the coloration of 

 birds and mammals we deal not with 

 any one cause, but with a varied and 

 complex tissue of causes. Forces have 

 been at work to develop concealing 

 coloration in many species, and counter- 

 vailing forces have worked with greater 

 or less strength to counteract the in- 

 fluence of the first, in some species com- 

 pletely succeeding and in others partially 

 succeeding. Some birds and mammals 



