GAY PLUMES AND DULL 



back is more like that of the rocker reversed; it 

 touches head and tail, and has far less freedom of 

 movement than has the nuthatch. The head of the 

 latter often points straight out from the tree, and 

 the eye takes in all the surroundings to an extent 

 that the creeper's cannot. 



Of course it is not safe to claim that one can al- 

 ways put his finger upon the exact thing that makes 

 one species of birds more numerous than an allied 

 species ; the conditions of all animal life are complex, 

 and involve many factors more or less obscure. 

 In the present case I am only trying to point out 

 how slight a part color seems to play in the problem, 

 and how prominent a part food plays. Our ruffed 

 grouse holds its own against the gunners, the trap- 

 pers, the hard winters, and all its numerous natural 

 enemies, not, I think, because it is protectively col- 

 ored, but because it, too, is a miscellaneous feeder, 

 ranging from berries and insects to buds and leaves. 

 The quail has the same adaptive coloring, but not 

 the same range of food supply, and hence is more 

 easily cut off. Birds that subsist upon a great variety 

 of foods, no matter what their coloring, apparently 

 have the best chance of surviving. 



VI 



There seem to be two instincts in animal life that 

 work against the influence of environment upon 

 the colors of animals, or the tendency in Nature to 

 87 



