BIRDS. 



127 



And," continues Mr. Milne, "for some years after the woodmen 

 complained that they could not get enough seed for planting, the 

 cones were so barren." 



Now, around Perth, Mr. Malloch has only one entered on his 

 registers between 1893 and 1898, of date 17th November 1894; so 

 their extensions are by no means general, but seem steady and 

 confined for the most part to a more or less continuous drift south- 

 wards, which can hardly fail to give the impression that their 

 advances are systematic, and resulting from congestion at their 

 older and more northern headquarters. As pointed out in a pre- 

 vious treatment of the species {vide our Fauna of Moray), as 

 these northern nesting straths and forests become thus congested, 

 the pressure becomes greater, and we have seen that considerable 

 winter visitations have been witnessed in the west of the mainland 

 of Scotland, and even extending to the isles ; and of necessity a 

 migration has been performed to relieve this decided congestion over 

 a vast area, represented by the whole forests of Speyside, and the 

 increase at many localities in the north-east of Moray and as far 

 north as Sutherlandshire. When these northern localities, which 

 are at present suitable for their healthy occupancy, are filled, the 

 surplusage in the natural course of procreation and increase must, 

 by a very evident Natural Law, escape to pastures new, whether south 

 or east or west. 



At the present time, their dispersal appears to have received 

 most checks in a westward direction. In that direction the advance 

 is certainly slowest, except that in quite recent years an autumn 

 migration has developed, and been duly recorded, down along the 

 west coast ; and even a somewhat similar movement has been in- 

 dicated in some of the Outer Hebrides, and such extensions of the 

 westerly drift of the migrants of any species which formerly has 

 only been known to occupy eastern areas in the nesting season, have 

 always struck me as a distinct indication of internal pressure from 

 congestion, and preliminary to a possible extension of breeding range 

 in the future. Needless to repeat that I do not mean the above 

 remark to be held as applying to all species, for in some at least there 

 is good evidence that quite a different pressure may be exercised 

 from west to east instead of from east to west. Need I refer to 

 any of those I have before instanced 1 I hope not, as I cannot 

 make my views any clearer than I have done before ; though, from 

 the absence of remark about them, perhaps they have not been 

 made clear enough. 



