ADAPTATION TO ENVIRONMENT 29 



ROCKY MOUNTAIN 

 WHITE TAILED 



PTARMIGAN 



SHOWING 



TRANSITIONAL PLUMAGE 



1 MOTHER *NP CHICKS 



JUL.Y 11,1900. 



2 FALL PLUM/^GE 



SEPT. 23,1902: 



3 WINTER PLUMAGE 



Nov. o 



Photos by 



R WAE.R.EN 

 Mt. Emmon.s 



nison. C-oorvty 

 COLOR. APO. 



FIG. 1. PROTECTIVE COLORATION OF THE ROCKY MOUNTAIN WHITE- 

 TAILED PTARMIGAN. 



