THE PARADISE FLYCATCHER 161 



gamous ones there must of necessity be considerable 

 competition for hens. 



The second point upon which I desire to lay stress 

 is the active part taken by the cock paradise flycatcher 

 in incubation. This, again, is, I believe, nothing very 

 uncommon, even in sexually dimorphic species, for 

 I have myself put a cock minvet (Pericrocotus peregrinus) 

 off the nest. Yet this fact seems to dispose of Wallace's 

 theory that the more sombre hues of the hen are due 

 to her greater need of protection, since she alone is 

 supposed to incubate. 



As a matter of fact, a bird sitting on a nest is not, in 

 my opinion, exposed to any special danger, for it seems 

 that birds of prey as a rule only attack flying objects. 



Finally, there is the extraordinary metamorphosis 

 undergone by the cock in his fourth year. It is 

 difficult to see how this can have been caused by the 

 preference of the hen for white cock birds, since a great 

 many chestnut ones are observed to breed ; the di- 

 morphism must, therefore, have originated late in the life 

 history of the species, and although a hen bird might 

 prefer a white to a chestnut husband, it is difficult to 

 believe that she would prefer a skewbald one, and this 

 skewbald state must have been an ancestral stage if we 

 believe that the transition is due to feminine selection 

 of white birds. I may be asked, " If you decline to 

 believe that the hen has greater need of protection 

 than the cock, how do you account for the phenomena 

 of sexual dimorphism, and if it is not sexual selection 

 which has caused the white plumage of the cock 

 paradise flycatcher to arise, what is it ? " 



M 



