Photographs by W. P. Dando, F.Z.S. 
RUDDY SHELDRAKE, HYBRID SHELDRAKE. 
HYBRID BIRDS. 
I1—By FRANK FINN, B.A., F.Z:S. 
as lover of birds may congratulate himself on the fact that his favourite class of 
animals has supphed more information to the student of the fascinating and 
difficult problems of hybridism than any other, birds being themselves more prone to 
hybridism than other creatures, and having been studied by so many observers both 
in the wild state and in confinement. 
Wild hybrids are indeed rare, but they are of much more frequent occurrence 
than is generally supposed. They are most numerous among the species of the Grouse 
family; the cross between the Blackcock (Lyrwrus tetriz) and the Capercailzie (Tetrao 
urogallus) occurs every year, and has even received a special name (Rakkelhane) from 
Scandinavian sportsmen. Many instances of crosses between the Blackcock and Red 
Grouse (Lagopus scoticus) have also been recorded; but, curiously enough, the latter 
bird and the Ptarmigan (Lagopus mutus), although so much more nearly related, 
appear never to interbreed. Various other grouse crosses have occurred, but for variety 
of hybrids the Grouse must give place to the Ducks. In this family at least two 
dozen distinct crosses have been observed, some of them several times, such as those 
between the Mallard (Anas boscas) and Pintail (Dafila acwta) and between the Smew 
(Mergus albellus) and Golden-Hye (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 differmg practically only in colour, as opposed to those 
I have mentioned above, where the form and size are also distinct, come into contact 
locally: Im 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 imtermediates. This occurs where the Carrion Crow (Corvus corone) meets the 
Hooded Crow (Corvus corniz); where the Huropean and Himalayan Goldfinches 
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