562 THE POPULAR SCIENCE MONTHLY 



Among the genera that move erect without crouching in the vicinity 

 of their prey, and catch it upon surfaces below their level, and which 

 are commonly effaced as to their top contours, by white in their costume, 

 are herons, cranes, pelicans and the omnivorous swans, geese and ducks. 

 And a similar use of white effaces the rear view of an immense number 

 of widely separated members of the animal kingdom which tend to be 

 seen by their pursuers against the sky. Among these are hares, deer 

 and antelopes, ground-nesting birds that commonly spring on wing 

 from the nest on being flushed, such as waders, ducks and geese, many 

 passerines, and such hawks as nest on the ground. These all wear some 

 white rump or tail pattern, which obliterates them in the most magical 

 way, against the sky, exactly while, in getting under way, they are for 

 a fateful instant within springing reach of the cougar, lynx or fox that, 

 with head close to the ground, has crept up to them. White patterns 

 abound on aerial passerines in general, but even white wing bars are 

 lacking from such as keep so close to the ground that no enemy sees 

 them against the sky. And among small rodents none has top-white 

 unless, like the jerboa, he jumps high enough to be seen by his pur- 

 suer against the sky. 



Now, while these white top patterns seem to be universally employed 

 wherever they can be of the above service, on the other hand, they are 

 conspicuously lacking from the rears of such ground-nesters as habitu- 

 ally run, instead of flying from the nest, and thereby avoid showing 

 against the sky, to terrestrial eyes. Such are gallinaceous birds, tina- 

 mou, rails and many other sedge-haunting species. (Gallinules whose 

 upturned tails present, as they fly, a white sky-picture, probably keep 

 their tails down when they slink from their nest.) 



The white patterns on the breasts of several kinds of bear, which 

 Mr. Pocock has classed as warning colors, serve perfectly the same 

 obliterative purpose that we find in all the rest of upward-facing white 

 patterns. (These patterns face upward when the bear stands erect, i. e., 

 face upward to the degree necessary for catching top light.) Now, we 

 find that for recognition a monochrome silhouette, especially in a 

 thicket, is far superior to a patterned one (see Fig. 8), and also Ave have 

 small grounds for thinking that such bears, when standing erect in the 

 jungle, have need to be afraid of being attacked by mistake by any of 

 their neighbors that would avoid them if they recognized them. On the 

 other hand, be the bear's object, in thus assuming man's attitude, either 

 aggression or defense, he gets the same general advantage out of escap- 

 ing detection, and the chance of enjoying this boon is, as we now realize, 

 greatly increased by the chance of this light patch being, at the right 

 moment, just sufficiently illuminated to pass for a sky-hole through the 

 dark mass of shrubbery of which the erect bear forms the dark center. 

 All woodsmen know that when one has followed with the eye some bird 



