Ornithological and Other Oddities 



least two dozen distinct crosses have been ob- 

 served, some of them several times, such as those 

 between the mallard (Anas boscas) and pintail 

 (Dafila acuta), and between the smew (Mergtis 

 albellus) and golden-eye {Clangula glaucion). 

 Wild hybrids between the small birds are much 

 rarer, but several cases of the interbreeding of 

 the linnet and the goldfinch with the greenfinch 

 are known. Generally speaking there is, however, 

 little wild hybridism outside the game-birds and 

 waterfowl, with the exception of a special class of 

 cases now to be noticed. 



This is when two species differing practically 

 only in colour, as opposed to those I have men- 

 tioned above, where the form and size are also 

 distinct, come into contact locally. In cases like 

 these a great deal of interbreeding takes place, 

 and, the hybrids breeding back to the parent 

 stocks, the locality of meeting is populated by a 

 collection of intermediates. This occurs where 

 the carrion crow (Corvus corone) meets the 

 hooded crow {Corvus comix) ; where the Euro- 

 pean and Himalayan goldfinches (Carduelis car- 

 duelis and C. caniceps) encounter each other ; and 

 where the blue rollers of India and Burma 

 (Coracias indicus and C. affinis) come into con- 

 tact, to say nothing of many other cases. 



It is a question, however, whether this can be 

 called true hybridism, since it may reasonably be 



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