Sexual Selection 297 
Entirely new light upon the seasonal appearance of epigamic 
characters is shed by the recent researches of C. W. Beebe}, who 
caused the scarlet tanager (Piranga erythromelas) and the bobolink 
(Dolichonyx oryzivorus) to retain their breeding plumage through 
the whole year by means of fattening food, dim illumination, and 
reduced activity. Gradual restoration to the light and the addition 
of meal-worms to the diet invariably brought back the spring song, 
even in the middle of winter. A sudden alteration of temperature, 
either higher or lower, caused the birds nearly to stop feeding, and 
one tanager lost weight rapidly and in two weeks moulted into the 
olive-green winter plumage. After a year, and at the beginning of 
the normal breeding season, “individual tanagers and bobolinks were 
gradually brought under normal conditions and activities,” and in 
every case moulted from nuptial plumage to nuptial plumage. “The 
dull colors of the winter season had been skipped.” The author justly 
claims to have established “that the sequence of plumage in these 
birds is not in any way predestined through inheritance......, but 
that it may be interrupted by certain factors in the environmental 
complex.” 
1 The American Naturalist, Vol. xu11. No. 493, Jan. 1908, p. 34. 
