JHE WARBLERS, 179 



through an entire moult, but the plumage thus acquired is not 

 very different from the one it wore before, and its first winter 

 dress is very similar to that of its parents. If there is any 

 variation in the winter plumage of the adult and young birds, 

 it generally consists in the under surface of the latter having a 

 tinge of yellow. Before returning, however, to its breeding 

 place in the following spring, a migratory Warbler (and most 

 Warblers are migratory) goes through another complete moult 

 in its winter quarters, so that the spring plumage of both old 

 and young bird is precisely the same. In the Thrushes, as 

 will be seen later on, the method of moulting and the plumage 

 of the young birds is different from that of the Warblers. 



THE TRUE WARBLERS. GENUS SYLVIA. 

 Sylvia, Scop., Ann. I. Hist. Nat., p. 154 (1769). 

 Type, S. sylvia (Linn.). 



The classification of the Warblers depends as much on the 

 style of plumage as upon structural characters, and it is not 

 surprising, therefore, to find that it is a task of extreme diffi- 

 culty to classify these birds in a satisfactory manner. The 

 monographic work done by Mr. Seebohm in the " Catalogue 

 of Birds " is of great assistance in the study of the Warblers, 

 but it is remarkable that the characters assigned for the dif- 

 ferentiation of such obviously distinct forms as, for instance, a 

 Garden-Warbler and a Reed- Warbler, should be of so trivial a 

 character. 



Thus, if we summarise the peculiar features which are sup- 

 posed to be distinctive of the genus Sylvia we find that they 

 amount to the following : Bill typical, not flattened like that of 

 a Reed- Warbler, but somewhat slender, with rounded culmen 

 and exposed nostrils, and the base of the lower mandible paler ; 

 the bastard-primary considerably less than half the second quill, 

 but extending well beyond the primary-coverts, occasionally 

 not reaching to this distance ; the axillaries never yellow, but 

 either white or gr^y or brown ; the bill from the gape to the 

 tip less than the length of the middle toe and claw; the 

 rictal bristles, three in number, weak, and the supplementary 

 hairs nearly obsolete, according to Mr. Oates, who also gives as 



N 2 



