THE BIRD DEPARTMENT 



465 



But to return to the gorgeous tanagers and the incon- 

 spicuous grouse, surely there is some reason for the dif- 

 ference in coloration which study might lead us to under- 

 stand. We soon discover that brilliant color in almost 

 every species is restricted wholly to the male bird and a 

 moment's thought convinces us that the law of " The 

 Survival of the Fittest " would soon weed out any bright- 

 colored females should they arise, by drawing attention 

 to their nests and inviting the destruction of their off- 

 spring. The very exceptions to the rule further sub- 

 stantiate it, for when bright colors are normal to the 

 females, as in the kingfisher and red-headed woodpecker, 

 nature protects the offspring by causing the eggs to be 

 laid in holes in trees or tunnels in the bank where the 

 female is entirely hidden from sight while incubating. 



Another means of protecting conspicuously colored 

 birds is by endowing them with extreme wariness and it 



THE KIXG BIRD AT ITS NEST IN ORCHARD 



The king bird is sometimes called " Bee Martin " because of its supposed habit 

 of destroying honey bees. Investigations have shown that it catches but few bees 

 and these mostly drones, and that it is a highly desirable bird because of the ob- 

 jectionable insects which it destroys and its habit of driving off crows and hawks. 



is seldom that any one of them will allow as close an 

 approach as do their dull-colored mates and relatives. 

 They seem to realize that they are conspicuous and rely 

 upon their alertness to escape. Moreover, is it not of 

 direct benefit to the species that there should be a con- 

 spicuous decoy to lure away from the vicinity of the nest 

 any enemy that should pass that way ? for even should the 

 male be seen and captured, the offspring might still persist. 

 Brilliancy of plumage probably originates in every 

 species through excess of strength and bodily vigor, and 

 this fact undoubtedly tends to perpetuate and increase the 

 brilliancy, whenever the bright colors are not directly dis- 

 advantageous to the species, by assuring to the brilliant, 

 vigorous bird the best mate and strong offspring. Then 



it may well be asked why the males of all species are not 

 conspicuously colored and able to rely upon their wits to 

 escape their enemies. But think for a moment which are 

 the brightly colored birds and which the dull. The 

 tanagers, the trogons, the honey creepers, the tropical 

 flycatchers, the buntings, the gulls, the terns, the herons 

 and the flamingoes are all birds that spend their lives 

 either in the tree tops or in the great open spaces where 

 enemies cannot lurk. The nearer the ground a bird 



A LEAST BITTERN ON ITS NEST -IN CATTAILS OF THE MARSH 



An example of mimicry among birds the shape of the bird in this posture, as 

 well as the color, simulating its haunts, so that it is most difficult to see it among 

 the cattails. 



dwells and the denser the coverts, the nearer may an 

 enemy approach and the more easily may it lie concealed. 

 Thus it is clear why the gaudy tanager is confined to the 

 tree tops and why the streaked sparrow must simulate its 

 dry grass haunts if it would persist. Birds dwelling 

 within reach of skulking enemies seldom wear brilliant 

 colors or bear feathers that are continuously conspicu- 

 ous. They are protectively colored and often fit in with 

 their environment to such an extent as to be practically 

 invisible. The ways in which this concealment is brought 

 about are varied and interesting. 



Concealing Coloration 



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 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 



