The Making of Species 



Wallace's view that the dull plumage of the 

 hen bird is due to her greater need of protection 

 is based on the assumption that the hen bird alone 

 takes part in incubation. 



Is this assumption a correct one? 



It certainly is not in all cases. As D. Dewar 

 has stated in Birds of the Plains, the showy 

 white cock Paradise Fly-catcher (Terpsiphone 

 paradisi] sits in broad daylight on the open nest 

 quite as much as the hen does. And this may 

 prove to be true of many other species of 

 birds. Again, the cocks of the various species 

 of Indian sunbirds are brightly coloured while 

 the hens are dull brown. In these species the 

 hen alone sits on the eggs, but, as the nest is 

 well covered-in, the hen might display all the 

 colours of the rainbow without being visible 

 to passing birds. Moreover, as D. Dewar 

 pointed out in a paper read before the Royal 

 Society of Arts (Journal, vol. Ivii., p. 104), 

 although, in most species of Indian dove, the 

 sexes show little or no dissimilarity, there is one 

 species (CEnopopelia tranquebarica) which ex- 

 hibits considerable sexual dimorphism. But the 

 nesting habits of this peculiar species are in 

 all respects similar to those of the other species 

 of dove. Why then the marked dissimilarity of 

 the sexes ? 



Another objection to the theory of Wallace is 

 that urged by J. T. Cunningham (Archiv fiir 



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