Existing Theories not Satisfactory 



exercise has caused the development and in- 

 heritance of plumes in some species, why not 

 in the others ? 



Again, Cunningham is not correct in saying 

 that sexual dimorphism is " virtually absent " in 

 the Columbidae. Few birds display so striking a 

 sexual dimorphism as the Orange Dove (Chryscena 

 victor) of Fiji, in which the male is bright orange 

 and the hen green. We have already cited the 

 case of the curious sexually dimorphic red turtle- 

 dove. Now, the courting attitudes and actions 

 of this species are precisely the same as those of 

 other allied turtle-doves ; why, then, have these 

 exercises caused only one species to become 

 sexually dimorphic ? 



Our survey of the more important attempts 

 which have been made to explain the phenomena 

 of sexual dimorphism leads to the conclusion that 

 these still require elucidation. We have weighed 

 each theory in the balance and found it wanting. 



The outstanding feature of sexual dissimilarity 

 is the apparently haphazard manner of its occur- 

 rence. 



We have already alluded to the case of the 

 doves in India. In that country four species are 

 widely distributed namely, the Spotted Dove 

 (Turtur suratensis), the Ring or Collared Dove 

 ( Turtur risorius), the Little Brown Dove ( Turtur 

 cambayensis\w\& the Red Turtle-dove (CEnopopelia 



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