^°i^i^'] COLE, Variations in the Black-hacked Magpie. 51 



Variations in the Black-backed Magpie 



[Gymnorhina tibicen) 



P.y C. !•■. COIJ-:. R.A.O.L'., Wan^^iratta, Xictoria. 



I'robably there i.=; no other species Ijelonging to the avifauna 

 of Austraha that varies so nmch in the adult ])lumage as does 

 Gymnorhina tibicen, and in so conspicuous a type of marking, as 

 that ui)on the back, from which it derives its vernacular name 

 ■'IJlack-backed .Magpie," thus separating, at a cursory glance, this 

 bird from its allied s])ecies, the White-backed Magpie ( G. 

 Icuconota). Hoth species are to be met with in the north-east 

 of \'ictoria, tibicen being common, whilst leuconota is rather 

 rare. It is no uncommon sight to see from 50 to 100 of the 

 libicen s]iccies, in the late autumn, feeding upon freshlv-f allowed 

 land. 



It was owing to seeing odd "white-backed" birds associated 

 with the "black-backed" birds, and others having this black 

 marking splashed with white, that my suspicions were aroused. 

 The variations in the markings upon the back of many birds 

 dissimilar from that of the birds with the typical marking were 

 many and interesting. These variations were features peculiar 

 to this species. G". tibicen, and that this variation in colour upon 

 the back of individual birds, from a uniform l)lack to white, was 

 strong evidence that many of the "white-backed" birds associated 

 with the other types already referred to. were really variations of 

 G. tibicen. 



If the tibicen and leuconota sjjecies had, and were still mating, 

 this would account for this variation in the colour of the back. 

 Probably, at times, this mating does occur wdiere the two species 

 inhabit the same locality, but the writer has failed to prove that 

 this is so. If this mating should take place, it would be a natural 

 sequence that many of the progeny would have this conspicuous 

 marking upon the back, varying from black to white, as depicted 

 in Figures A, B. C, D, E, and the progeny would perpetuate this 

 variation. ]\Iy object in compiling this article upon this species 

 is to prove, after years of close observation, that this variation 

 is perpetuated, and that a "white-backed" Magpie seen in the 

 north-east of \'ictoria is not necessarily a G. leuconota, but it may 

 be a variation of G. tibicen. There is a probability of this varia- 

 tion increasing to such an extent in numbers as to exceed the 

 ;)arent-typed species — the "Black-backed" Magpie. Roughly 

 speaking, in \\"angaratta and adjacent districts the percentage 

 of birds classed under "variation" is very noticeable, at times 

 five out of six birds seen being variations, and it may be safely 

 stated that approximately 30 per cent, to 35 per cent, are varia- 

 tions. 



