490 



PERCHING BIRDS 



circumstance that the nostrils arc clear of the line of the forehead ; the 

 tail may have either ten or twelve feathers, although the latter number 

 obtains in all the British species ; and there is a spring and an autumn 

 moult, the former of which may, however, be incomplete. The group 

 is confined to the Old World, and a large number of its representatives 

 are migratory. 



Much stress has been laid on the fact that warblers differ from 

 thrushes by the absence of spotting in the young. The circumstance 

 is not, however, one of any great importance from a systematic point of 

 view, but is merely evidence that the warblers are the more specialised 

 of the two groups. In the adults of both the original spotted dress 

 has been lost, and in the warblers the same thing has occurred in the 



)-oung, which have assumed a 

 plumage similar to that of their 

 parents. 



From the foregoing obser- 

 \-ations it will be manifest that 

 practice, rather than reliance 

 on definition, affords the surest 

 means of recognising the mem- 

 bers of the warbler group. 



The whitethroat tj'pifies a 

 genus in which the beak is 

 comparatively slender, with a 

 rounded upper surface, and its 

 lower half paler at the base 

 than elsewhere ; the small first primary quill of the wing is consider- 

 ably less than half the length of the second ; the feathers of the 

 a.xillary region may be white, grey, or brown, but are never \'ellow ; 

 there are only three well-developed bristles on each side of the gape 

 of the beak : and the beak itself, from gape to tip, is shorter than the 

 middle front-toe, inclusive of the claw. 



The whitethroat itself is of the size of a hedge-sparrow, that is to 

 sa)', 5^ inches in length, and may be recognised by the generally 

 smoky grey hue of the upper-parts, the chestnut margins of the wing- 

 coverts and secondary quills, and the white under-parts, tinged on the 

 breast with purplish, darker on the flanks, and becoming brownish 

 white on the abdomen. A further aid to the identification of the 

 species is afforded by the circumstance that the first, or " bastard," 

 primary wing-quill is not larger than the feathers of the greater wing- 

 covcrts. The hen is duller-coloured, without the purplish tinge on the 



VVIHTKTIIKUAT NIAI.K 



