MIGRATION 
LXXXI 
The Sol way Firth has been hkened by H. A. Macpherson 
to "a great ornithological junction," and " this likening 
of the meeting place of the two main hnes of Bird flight 
to a railway junction was a very happy analogy." 
" Species that are quite abundant along the east coast 
of England and Scotland may cross England at its narrowest 
part opposite the Solway Firth, either in scanty numbers, 
very rarely, or not at all. West of the Solway Firth such 
species become scarcer still. It is noteworthy that a directly 
northward flight in spring is rather exceptional ; all have a 
more or less westward bend in their direction. On the 
contrary, the autumn flight is far more direct, and goes 
almost, if not quite, due south."* 
Mr. G. F. Scott-EUiot has stated : " Civilisation and 
human immigrants have followed the hne of the Glasgow 
and South-Western Railway from the earliest prehistoric 
times. This is due probably to the depth and great inland 
extent of the valley, "f This valley of the Nith is a very 
well-defined " fly-line," up and down which the birds pass 
in a north and south direction, in their vernal and autumnal 
migration, respectively ; their emigration flight being in a 
direction which would take them down channel midway 
between the Isle of Man and the opposite headlands of 
England. 
The other " fly-Hne," utihzed by such species as the Field- 
fare and Redwing, is directly east or west, according to 
season. 
The average dates of arrival and departure of the various 
species have been given, so far as possible, when writing of 
the birds of Dumfriesshire individually in the subsequent 
pages ; but it should be remembered that just as " One 
swaUow maketh not summer," so the appearance of an indi- 
vidual is no real proof of the general immigration of that 
species. For example, towards the end of February or early 
* Ann. Scot. Nat. Hist., 1903, p. 202. 
t Flora of Dumfriesshire, p. ix. 
All 
