SCHOOL DEPARTMENT 



Edited by A. A. ALLEN, Ph.D. 



Address all communications relative to the work of this 

 department to the Editor, Cornell Universit}', Ithaca, N. Y. 



CONCEALING COLORATION OF BIRDS 



In the last issue of Bird-Lore we discussed the general coloration of birds 

 and planned to consider the principles of concealing or protective coloration 

 at this time. 



There is one principle which underlies the coloration of all protectively 

 marked birds which does more than anything else toward rendering them 

 inconspicuous, and that is the principle of 'counter-shading', as it was named 

 by its discoverer, the late artist-naturalist, Abbot Thayer. It had long been 

 known by artists that to make objects appear solid and conspicuous on the 

 canvas, one must paint in their shadows, but it remained for Thayer to apply 

 the reverse of this practice, and to point out that the way to make solid objects 

 appear flat and inconspicuous was to paint out their shadows. He applied 

 this principle to the coloration of animals and recognized that protective 

 coloration is brought about largely by the lightest colors being placed on the 

 throat and belly, which parts are thrown into the deepest shadow, and the 

 darkest colors on the top of the head and back, which receive the greatest 

 light. Between the back and the belly there is a gradual change to lighter, 

 exactly counter-matching the amount of shadow, so that the apparent solidity 

 of the bird is thus destroyed or 'painted out.' 



This principle has been admirably illustrated by the celebrated bird artist, 

 Louis Agassiz Fuertes, with the two bird 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 balance the shadows exactly, with the result that, to 

 the amazement of onlookers, this one gradually 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 loses 

 its solidity, appears flat, and being 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 



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