224 WAGTAILS AND PIPITS 



in the Hebrides, and part of the stream at least appears to pass through 

 the Shetland group, going, presumably, to the Fseroes and Iceland ; (3) at 

 the same time a very slight migration takes place through the more eastern 

 districts of Great Britain as far north as the Firth of Forth. As has been re- 

 marked, this is one of the few birds whose migrations are largely confined to our 

 western coasts ; it is also remarkable in that its vernal passage is so much better 

 known than its autumnal one. Its movements at the latter season are probably 

 the counterpart of those described above : (1) Details of the autumnal emigration 

 appear to be wanting ; (2) the autumn passage on the western route has only been 

 partially recorded, e.g. from the Hebrides ; the season is remarkably short, ex- 

 tending from mid- August to mid-September; (3) to the Lothians the white- 

 wagtail is known as a bird of double passage, and it probably is so to the eastern 

 districts of England as well, but the available information is especially incomplete 

 for autumn. On the east of Scotland north of the Forth, as well as on the east 

 of Ireland, the white- wagtail is of exceptional occurrence, and there is some ground 

 for believing that the large numbers which pass through Fair Isle, and the Shet- 

 lands generally, take the western route. [A. L. T.] 



4. Nest and Eggs. Practically indistinguishable from those of the pied- 

 wagtail. (PL B.) Average size of 100 eggs, -8 x '59 in. [20'43 x 15-11 mm.]. 

 The breeding habits of the two races are also similar. [F. c. R. J.] 



5. Food. Similar to that of the pied- wagtail. [A. L. T.] 



6. Song Period. Spring and summer according to Naumann, who adds 

 that the hen also sings, her efforts being, however, much less finished. One 

 would expect an autumn song-period. [F. B. K.] 



GREY-WAGTAIL [Motacilla boarula, Linnaeus [M. melanope, Pall.]. 

 Rock-wagtail. French, hochequeue ; German, graue Bachstelze ; Italian, 

 ballerina gialla]. 



i. Description. Distinguished from all the other British wagtails by 

 the great length of the tail, and the uniform slate-blue of the upper parts. 

 (PI. 25.) The male, in breeding dress, has the upper parts slate-blue, relieved 

 by a white superciliary stripe, and a narrow line of white extending from the 

 base of the beak backwards below the auriculars, to terminate on the sides of 

 the neck; the upper tail-coverts are of a greenish yellow. The throat is 

 black, and the rest of the under parts are sulphur yellow, brightest on the under 



