338 BIRD BEHAVIOUR 



come extinct with the killing off of the whole stock. 

 One can understand how such a variety can recur, 

 from the account given by a contributor to Wright's 

 " Poultry Book " of the constant recurrence of a 

 few silver-grey ganders in his strain of the ordinary 

 dark-grey Toulouse Geese, after he had once used a 

 gander of that colour. 



Albinistic variation in birds is commoner in 

 New Zealand than anywhere else, and it is interest- 

 ing to note that it affects the introduced British 

 birds as well as the native species, no doubt because 

 in both cases in-breeding has followed the intro- 

 duction, natural or artificial, of but a small stock ; 

 I have noticed that the plumage of most native 

 New Zealand birds is extraordinarily soft and fluffy, 

 no doubt another form of degeneration, as soft 

 loose plumage is one of the surest signs of degeneracy 

 in captive or domesticated birds. Albinism is gene- 

 rally replaced by lutinism, or yellow coloration, in 

 green birds, whether pure green or olive-green; 

 thus we are familiar with the yellow variety of the 

 Canary, originally an olive-green bird, and in India 

 a yellow variety of the pure green Ring-necked 

 Parrakeet not unfrequently occurs. Such Parrakeets 

 retain the red beak, and, if males, the red neck- ring ; 

 red having a curious tendency to persist in varieties 

 otherwise abnormally coloured. 



Melanism or abnormal blackness is usually rarer 

 than albinism, but much commoner in birds of 

 prey 'except Owls. It must be remembered that 

 albinos and lutinos often have pink eyes, and there- 



