Unfortunately it is quite impossible to give any key which will 
render it easy to discriminate these races one from another, as all the 
differences are ones of comparative depth of colouring only, although 
typical specimens are easily separable when laid alongside one another. 
Roughly speaking it may be said of the five subspecies that— 
Streptopelia turtur turtur is a very rare straggler from north Persia 
and Asia Minor. 
S. turtur arenicola is an equally rare straggler into north-west India 
from southern Persia and Arabia. 
S. turtur ferrago is a migratory bird, breeding in the Himalayas 
and visiting almost every part of India in the cold weather. 
S. turtur meena is the common resident form over Continental 
India, eastern India, and Burma. 
S. turtur orientalis is the resident species in the extreme north. 
From the key it is seen that I consider all the above birds to be 
subspecies of Streptopelia turtur, whilst Hartert and others consider 
S. orientalis orientalis and S. orientalis meena form another group. 
To me, however, they all appear to be geographical races of the same 
species, and if it is correct to say that turtur turtur grades into turtur 
arenicola, and that again into turtur ferrago, so it seems to me that turtur 
arenicola grades into turtur orientalis, and there are a few birds in the 
British Museum Collection which form an excellent connecting link 
between the two subspecies. 
