AND OTHER WAGTAILS. 137 



that we must look for close specific correspondence between the 

 two Continents, instead of divergence as regards the same spe- 

 cies. Certainly, the same Motacilla ought not to be notably 

 different in the two Continents. 



Of the two Wagtails in question, M. alba and M. dukhu- 

 nensis, Mr. Seebohm states nothing regarding the song of each. 

 All black and white Wagtails have songs, and that of M. mada- 

 raspatana is particularly good. Suppose M. alba and M. du- 

 khunensis have different songs ; what then ? But similarity of 

 song won't prove identity, for I don't think any one could dis- 

 tinguish the songs of Erythrosterna parva and E. liyperytlira 

 without seeing the birds. The call-notes of the black and white 

 Wagtails are wonderfully alike, so are those of the Budytes. 



The points of difference in M. alba and M. dukhunensis 

 worth noting are : — 



1. M. alba has, as a rule, a darker grey back than the other. 



2. M. alba does not show nearly such white greater coverts 

 as the other bird, and it ought to do so if the same. It never 

 does, and on this alone specific identity is impossible. Now I 

 can always separate the immature of M. luzoniensis (M. alboi- 

 des apud Seebohm) by the superior whiteness of the greater 

 coverts, and this is the only mode of separation where both 

 birds occur — at Patna and Dinapore for instance. I, therefore, 

 from my own observation, attach the greatest importance to the 

 white wing-coverts that Mr. Seebohm thinks lightly of. With 

 reference to the white wing-coverts, Mr. Seebohm says : tl The 

 latter form seems to be confined to Siberia and India." 



Intermediate and apparently connecting examples are not 

 conclusive ; they prove great similarity or close affinity, and 

 nothing more. By intermediate or undecided birds, two species 

 could be united which the pronounced birds of each would 

 utterly condemn. A fully mature or perfect bird against a 

 fully mature bird is a fair comparison. Take a fine-plumaged 

 M. duhhunensis ; let it weather and wear for some months, 

 and its wing-coverts will have lost so much of their white ends 

 that it would match an alba in better plumage, and thus the 

 two species are bridged over ; falsely so, I say, in such delicate 

 cases fresh feather must be compared against fresh feather, and 

 birds should be of the same age. 



On the other hand, search the alba district for the white wing- 

 coverts of dtckhunensis, and you completely fail. 



3. Dukhunensis is, 1 believe, the larger bird of the two ; 

 and the bill is stronger and I think rather longer as well. 



4. The young of alba, in first plumage, have a pale 

 yellow or straw-coloured tint about the head, strongly differing 

 from the pure white of the lower parts. I have shot great 



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