THE 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 W aiblers. 
THE TRUE WARBLERS. GENUS SYLVIA. 
Sylvia, Scop., Ann. I. Hist. Nat., p. 154 ( 1 7 
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 ol 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 Warblets, 
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 ot 
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 grey 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 
