232 



BIRDS. 



As regards greater elevations, Hinxman found several pairs 

 nesting about Inchrory and in Glen Builg, and young birds were 

 met with at an elevation of 1700 feet.^ 



Since the last paragraph was penned, we have acquired very 

 good evidence of a similar wave, entering the Great Glen from 

 the south-west, and proceeding along the trough to the north-east.- 

 The Kedstart has been considered quite rare on Loch Ness until 

 lately, but is now — in 1895 — recognised as common by natives, who 

 know it by a Gaelic name. We observed it abundantly in June 

 1895 along the north-west side of Loch Ness, but along the tribu- 

 tary glen of Urquhart — over five miles of road between Drumna- 

 drochit and Loch Meiklie — we did not observe one single bird 

 during the same time, although there were equally suitable nesting 

 haunts in plenty. Again, around Inverness, Buckley had not seen 

 one bird in the same (present year, 1895) up to the dates of the 

 first week or ten days in June. 



We are indebted to an American author for the following diagrams, and we apply 

 it upon the same general principle (or law ?) which he illustrates under his title, — 

 Evolution of the Colors of North American Land Birds, by Charles A. Keeler, 

 p. 160 ; San Francisco, 1893. 



a a a a a 



0(1)0 



b b b b b 



In order to apply it to our present purpose : — 



Let the lines a b represent in each figure indicate the valley of the Spey. The 

 Redstart in its earlier stages of dispersal populated the main valley along what at 

 that time represented the great main line of least resistance (vide Mr. Keeler's argu- 

 ment, op. cit. pp. 159, 160). 



1 Mr. Sim found it abundant on Upper Dee around Braemar in 1893, but in 

 greater or less numbers it has occupied Deeside for years. It may be thought that 

 we go too much into details of distribution of our commoner species ; but we believe 

 that such details will some day serve a useful purpose, when the averages come to be 

 taken, not only of the distribution of difiiereut years and seasons, but also of the 

 advance or decline the species make in altitudinal range — from decade to decade, or 

 year by year, according to climatic changes. 



