87 



Variation in Birfcs. 



By F. Finn, B.A., F.Z.S. 



The subject of variations in birds is of the highest import- 

 ance to all students of the class, but fanciers are almost the only 

 people who can be said to have truly scientific knowledge of the 

 subject— that is, knowledge based on observation and experiment ; 

 for it is by observing and breeding from variations that all results 

 in the Fancy have been obtained. 



We may divide variations in birds into two classes ; those 

 which may be called spontaneous, and those which are induced 

 by circumstances. The former may be divided into two cate- 

 gories — individual variations, or the difference between one bird 

 and another (such variations forming a continuous series), and 

 abrupt or discontinuous variations, in which the varying indi- 

 vidual presents a wide difference from others of its kinds. 



Examples of induced variation are familiar to everybody 

 in the colour-fed Canary and those Bullfinches which become 

 black by the use of hemp seed. Spontaneous and natural 

 variation is, of course, familiar to all fanciers, for it is on these 

 that one places the value of show birds. I may instance the 

 Goldfinch as a bird which may vary much individually, whilst in 

 the Sparrow the individual variations are much less perceptible. 



Examples of abrupt or discontinuous variations may be 

 found iii such variations as the white Blackbird, cinnamon 

 Sparrow, etc. 



These abrupt colour variations generally fall under three 

 heads, the white, or more or less complete albino, the black type 

 or melanistic, and the pallid type, which may be either grey or 

 cinnamon. Such birds as the yellow Canary and Budgerigar 

 seem to represent the albino forms of green birds, since white 

 Canaries are almost unknown and white Budgerigars completely 

 so. Intermediate variations between the albino and normal form 

 are of course common, being the well-known pied specimens, of 

 which the London Sparrow furnishes numerous examples. It is 

 notable that intermediate forms between cinnamon or grey 

 varieties and the normal type seem very rarely to occur, although 

 the pale or pallid form may be varied with white. Thus, in the 



