THE PHYLOGENETIC VALUE OF COLOR CHARACTERS IN BIRDS. 



By Witmer Stone, A.M. 



The question of the origin and significance of color patterns and color combi- 

 nations in the plumage of birds is far from being satisfactorily explained. The 

 correlation between dark suffused tints and a dark humid environment* and 

 between light, bleached tones and an open, desert environment is familiar, even 

 though opinions may differ as to the part played in their production by light 

 and moisture on the one hand and protective resemblance on the other. 1 Further 

 cases of alleged concealing or protective coloration have frequently been cited 

 especially among the Limicoloe but certain recent attempts to account for 

 practically all types of coloration on these grounds are so extravagant as to make 



2 



seriously question the whole theory of protective color patterns 

 Were all color patterns the result of the concealment or protection that 

 they afford to the animal possessing them, there would certainly be little chance 

 for the resemblances in general type of coloration which we often find in species 

 of the same genus or same family, living in different countries and in different 

 environments. 



Furthermore in the light and dark forms characteristic respectively of desert 

 or humid areas we are able to ascribe only the relative intensity of the shades of 

 color to the effect of moisture or sunlight, not the fundamental color pattern or 

 primary tints, which are obviously due to other causes. 



In certain cases too the intensity of color and to some extent the color pattern 

 itself have been found to vary in island areas which so far as can be determined 

 have precisely the same environment. The most closely related forms so far as 

 coloration is concerned are often the most remote geographically. Mr. G. S. 

 Miller, Jr., has described such a condition among the mouse deer of the islands 

 of the Rhio-Linga Archipelago. 3 In such instances there seem to be certain in- 

 herited tendencies which develop along lines of least resistance as it were, in 

 different combination and varying intensity in each isolated colony, the resultant 

 forms converging or diverging without regard to geographic relationship. 



All these cases, however, relate to color forms differing but slightly from one 

 another and the brilliant color combinations especially frequent among tropical 

 birds are hardly to be explained by any theory of concealment or protection, 

 nor have they been satisfactorily explained in any other way. The problem is 



1 Cf. Beebe, Geographic Variation in Birds with Especial Reference to the Effects of Humidity. 

 Zoologica, I, No. 1, 1907, pp. 1-41 (N. Y. Zool. Soc. Publ.). 



* Cf. G. H. and A. H. Thayer, Concealing Coloration in the Animal Kingdom, 1900; also Barbour and 

 Phillips, The Auk, 1911, pp. 179-188, and Roosevelt, Bull. Amer. Mus. Nat. Hist., XXX, 1911, pp. 119-231. 



» Proc. U. S. Nat. Mus., XXXVII, pp. 1-9, Sept., 1909. 



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