592 THE AMERICAN NATURALIST [Vol. LI 



Dichromatism is then, both geographically and sys- 

 tematically, a widespread phenomenon in owls. The red 

 phase appears to be quite independent of geographic 

 locality in its origin. Hasbrouck attempted to show with 

 regard to Otus asio that the red phase had arisen gradu- 

 ally from the gray, which it was slowly supplanting in 

 certain areas. He believed that the grays inhabited 

 regions of greater humidity (Florida, northern range of 

 ncBvius) and the reds the drier interior, yet grays occur 

 in Florida and reds are found, though uncommonly, in 

 Maine. He also reported reds as occurring exclusively 

 in the relatively humid Mississippi valley. But, as Allen 

 pointed out, any such correlation with climatic or environ- 

 mental factors hopelessly breaks down because both t}T)es 

 are found indiscriminately over at least the greater part 

 of the eastern range. All writers agree that the two types 

 of plumage are independent of age, sex or season, and 

 that in many localities at least both occur together and 

 freely interbreed. Hasbrouck states, however, that gray 

 males far outnumber red males, while red females out- 

 number gray females 4 : 1. Confirmation of this point is 

 to be desired, as it suggests sex-linkage of the red con- 

 dition. It is further stated that on the continent of 

 Europe the red owls are said always to be females and 

 the grays males. 



All young birds of Otus asio are gray in the down, the 

 red first appearing in the feathers. Observations go to 

 show that red birds mated with red may give (1) all red 

 offspring, (2) all gray, or (3) both red and gray. When 

 one parent is red and the other gray, the same three re- 

 sults may follow. Further, Hasbrouck claims that gray 

 X gray gives always only gray young. This is probably 

 true, but since the result is based on observation of only 

 six matings of this kind in regions where reds occur, it is 

 much to be desired that further observations on this point 

 should be recorded. 



The obvious hypothesis to explain these facts is that 

 the red phase appeared as a mutation from the gray, and 



