Plumage of Herons 



colouring in the male is admired by the female ; 

 and in this manner he sought to overcome some 

 difficulties to his theory which certain birds 

 presented. 



Writing of the heron family, he says : 

 "The young of the Ardea asha are white, the 

 adults being slate-coloured ; and not only the 

 young, but the adults of the allied Buphus 

 coromandus in their winter plumage are white, 

 their colour changing into a rich golden buff 

 during the breeding season. It is incredible 

 that the young of these two species, as well as 

 of some other members of the same family, 

 should have been specially rendered pure white, 

 and thus made conspicuous to their enemies ; or 

 that the adults of one of these two species should 

 have been specially rendered white during the 

 winter in a country which is never covered with 

 snow. On the other hand, we have reason to 

 believe that whiteness has been gained by many 

 birds as a sexual ornament. We may therefore 

 conclude that an early progenitor of the Ardea 

 asha and the Buphus acquired a white plumage 

 for nuptial purposes, and transmitted this colour 

 to their young ; so that the young and the old 

 became white like certain existing egrets, the 

 whiteness having afterwards been retained by 

 the young whilst exchanged by the adults for 

 more strongly pronounced tints. But if we 

 could look still further backwards in time to 



3 1 ? 



