ON THE MINOR FAUNAL AREAS 13 



defined " avenues of advance" which I ventured to designate 

 " lines of least resistance? 



Next, I followed with a mammal the Squirrel. 1 This 

 animal similarly became extinct over a great area of Scotland, 

 but probably lingered in one old timbered tract of Moray. 

 It became resuscitated by various re-introductions, and we 

 traced its increase and extension of range, not only from these 

 centres, but also, as we believe, from the centre of its 

 resuscitation, caused by the planting of young timber in 

 close proximity to its indigenous haunts in the old pine 

 woods of Rothiemurchus, Abernethy, and Glen Feshie of 

 Spey. 



Again, I illustrated the decline of certain species partly 

 owing to the intervention of man, partly to changing circum- 

 stances among their native haunts, and other causes in a 

 paper upon the " Past and Present Distribution of some of 

 the Rarer Animals of Scotland," 2 and in a paper upon the 



' Great Spotted Woodpecker in Scotland " 3 a species once 

 again endeavouring to reach into Scotland through our 

 south-eastern Border counties in late years. 



I next followed with a series of papers upon the increase 

 and extension of range of several carefully selected species, 

 to show the varying avenues of approach and the circum- 

 stances affecting each species. 



Thus the Stock Dove 4 reached north and along our East 

 Coast. The Redstart, 5 long a breeding species in England 

 and the south, suddenly increased and spread north by a 

 peculiarly sinuous course, though one fairly accurately defined, 

 crossing between " Forth " and " Clyde," and then passing 

 up the West Coast through Argyll, increasing rapidly in 



1890 or thereabouts, crossed the dividing low cols between 



1 "The History of the Squirrel in Great Britain." (Edinburgh : M'Farlane 

 and Erskine, 1881.) 



2 Reprinted from "Zoologist," iSSi, pp. 8-23, 81-90, 161-171 ; and 1882, 

 pp. 1-9, 41-45 ; including notices of the (i) Wild Cat, (2) the Marten, (3) the 

 Polecat, and (4) the Badger. 



3 'On the Decrease of the Great Spotted Woodpecker in Scotland,' reprinted 

 from the "Zoologist," 1880, pp. 85-89 ; and a later paper on the same subject, 

 "Ann. Scot. Nat. Hist.," January 1892, pp. 5-17. 



4 'On the Stock Dove,' etc., " Proc. Roy. Phys. Soc. Edin.," 1883, 

 pp. 54-66. 



5 See "A Vertebrate Fauna of the Moray Basin" (Edinburgh: David 

 Douglas, 1895), under the species, vol. i. pp. 227-233. 



