1902.] F. Finn— General Notes on Variation in Birds, 1&3 



in proportion as they were more unnaturally treated. But this is not the 

 case ; the Java Sparrow and Collared Dove, bred for generations in small 

 cages, do not vary more than wild birds ; Avhereas the Pheasant, which 

 lives almost a completely natural life, is more variable than these. 



Climate does not directly induce colour- variation. The same colours 

 constantly recur in domestic birds in Europe and in India, without 

 variation in intensity. But some types of colouration may be absent 

 altogether in one or the other country. Here an indirect action of 

 climate, weeding out colours which are correlated with an unsuitable 

 constitution, ma}' be reasonably suspected. 



For so soon as a correlation between colour and some constitutional 

 quality is detected, it will probably be found that selection steps in 

 even in domesticated birds not bred for colour. Fighting cocks are very 

 variable in colour, being judged solely by courage and prowess in the 

 pit, and hence not selected deliberately for colour-points. Yet the 

 quasi-natural selection to which they are exposed seems to act in sup- 

 pressing some few colours ; cuckoo-coloured (barred-grey) birds — so 

 common among unselected fowls — were rare in English fighting game, 

 and I have never seen a cuckoo-coloured Aseel or Indian game-cock. In 

 this breed, which is even more courageous than the English game, and 

 has to fight under more trying conditions, the range of colour is alto- 

 gether more limited than among English birds; the hen, for instance, 

 is never of the wild "partridge" colour, and very rarely shows any 

 approach to it, though the cock usually has some likeness to the male of 

 Gallus galhis, the Red-Jungle Cock, his ancestor. 



On the other hand, the duck, domesticated in so unnatural a climate 

 as that of India, shows much the same variations as it does in England. 



Every species we have taken under our protection varies in its own 

 way; the two tame geese, Grey and Chinese, so nearly allied that they 

 produce a fertile hybrid, have not an identical range of variation. 



The variations of domestic birds have mostly an abnormal and 

 unnatural appearance, like casual variations among wild forms; this 

 may in some cases be explained. For instance, most domestic 

 species produce a white variety, and albinoes are common among wild 

 birds ; yet these are usually unfitted for the struggle for existence on 

 account of their colour, and accordingly we find few white species. Those 

 we do find may reasonably be supposed to have originated as albinistic 

 sports ; in the family where white species are commonest — the Herons — 

 we still find yet other species which commonly produce temporary or 

 permanent albinoes. A bird with the primary quills only white at once 

 looks unnatural, and yet it is an extremely common variation among 

 both tame and wild birds. Examination of the white quills, either in 



