466 



AMERICAN FORESTRY 



apply the reverse of this practice and to point out that 

 the way to make solid objects appear flat and inconspicu- 

 ous was by painting out their shadows. He applied thi> 

 principle to the coloration of animals and recognized that 

 the protective coloration is brought about largely by ani- 

 mals being colored lightest on the throat and belly, which 

 parts are thrown into the deepest shadow, and darkest on 

 the head and back which receive the greatest light. Be- 



of the marshes is striped like the shadows and lights of 

 the cattails, and the sandpipers and plover are specked 

 like the sand of the sea shore. 



With insects this simulation of pattern is often carried 

 to the extreme. There are butterflies and moths whose 

 markings imitate exactly the dead leaf or the bark upon 

 which they rest and even the shape of the wing is modi- 

 fied to make the simulation more complete. This scheme 

 of Nature is called mimicry. With birds mimicry is much 

 less perfect, but the screech owl, with its feathers drawn 

 close and its ear tufts erect, certainly simulates very well 

 a broken piece of bark. The night hawk, sitting length- 

 wise on the limb, looks like the broken stub of a branch 

 and the least bittern in the marsh, with its bill pointing 

 toward the zenith, the feathers of its long thin neck drawn 

 tight, resembles a broken reed ; so much so, in fact, that 

 they will often remain on the nest in this posture 

 until almost touched. 



In the plumages of certain birds that are normally 

 very difficult to see when at rest, we find a very different 



PkdobyH.D. Rrtd 



FIND THE SECOND BIRD MODEL 

 Two models were placed side by side on the gravel path. One was painted 

 uniformly and the other was " counter-shaded " like a real bird. The " counter- 

 shading has rendered the second model almost invisible, and as only a very 

 sharp eye can see it. it is perhaps well to explain that it is directly behind' the 

 plainly visible model. 



tween the back and the belly there is a gradual change to 

 the lighter, exactly counter-matching the amount of 

 shadow, so that the solidity of the bird is " painted 

 out," so to speak. 



This principle has been well illustrated by the cele- 

 brated bird artist, L. Agassiz Fuertes, with the two 

 models here shown. Two blocks of wood were cut out 

 in the general form of a bird and colored uniformly dark. 

 He placed them out-of-doors on a gravel walk in good 

 light and then with his brush proceeded to paint out 

 the shadows on one of them by adding touches of white 

 paint so as to just balance the shadows, with the result 

 that this one eventually disappeared from view. 



The principle of " counter-shading," like other great 

 discoveries, is very simple. The human eye and probably 

 all eyes judge the solidity of an object by the shadows 

 which it casts, and an object which throws no shadows 

 upon its underparts has no solidity. Through counter- 

 shading, then, the bird appears flat and when it does so, 

 it falls off into the background and becomes a part of it. 

 If, in addition, its color pattern is similar to its haunts, 

 it becomes practically invisible. And so we find the grouse 

 and the woodcock, living on the forest floor, with a color 

 pattern of spots and patches of light and dark brown ; 

 the sparrows and meadowlarks of the fields are streaked 

 with huffy and rufous, like the dead grasses; the bittern 



FIND THE KILLDEER 



The Icilldcer has some very conspicuous markings, but is difficult to see in its 

 haunts because these "ruptive marks" break up its continuity and render it 

 unbirdlike. 



color pattern which seems at variance with all that has 

 been said. Instead of there being a gradual transition 

 from the dark to the light areas, there is a sudden abrupt 

 change, often heightened by a black border. On the head 

 of the wood duck, for example, the white of the throat 

 extends up on the cheeks in the form of crescents. These, 

 together with the white stripes through the crest and the 

 black and white bars on the sides, would seem to make it 

 most conspicuous. Similarly with the killdeer, its brown 

 head is separated from its back by a conspicuous white 

 ring and its snowy breast is crossed by two coal black 

 bars. In spite of these marks, one finds that both the 

 wood duck and killdeer in their natural environments are 

 very inconspicuous, and we are led to believe that these 

 ruptive marks, as they have been called, serve apparently 

 to split up the bird into several pieces, destroy its continuity 

 of form and thereby conceal it by making it unbirdlike. 



One other class of markings we might consider here 

 since they are similar to the ruptive marks in being them- 





