MIGRATION. 
Throughout these remarks on Migration I must particularly 
acknowledge the assistance of Mr. R. Service, whose interest 
in the subject is so well known, and to his paper on Bird 
Migration in Solway "* I constantly refer. 
As has already been pointed out, the avifauna of a county 
depends greatly upon its physical features, while its geo- 
graphical position is an even more important consideration. 
Situated as Dumfriesshire is in the western half of Great 
Britain, it is not to be wondered at that many of the rare 
stragglers which from time to time occur on the east coast, 
should never have penetrated so far west as to enter the 
confines of the county, which seems in fact to lie just outside 
the range of the general east coast migrants. 
The map will show that the Mth, the Annan, the Esk, 
and in fact all our rivers, flow into the Solway Firth. " All 
of these flow in the same general direction, and have for ages 
been scooping out valleys that all trend in a southerly 
direction. The Firth that receives this large volume of 
fresh water has its outlet into the Irish Channel, the arm of 
the sea that divides Scotland and England from Ireland. 
There is no doubt that in comparatively recent geologic 
times the Irish Channel was a great tidal river, of which the 
Solway streams were its northernmost tributaries, and that 
this ancient river valley was the route by which the birds 
came and went in long by-past ages — a route which has left 
so strong an impression on posterity that the birds still 
travel along what is now a broad sea-way. "f 
* Ann. Scot. Nat. Hist., 1903, pp. 193-204. 
t Op. cit., 1903, p. 193. 
