198 ANNALS OF SCOTTISH NATURAL HISTORY 



pedicle of the arch of the last cervical vertebra is opposite 

 the centre of the foramen magnum, the spinal canal con- 

 sequently passing into the skull in an oblique direction. 



INCREASE AND DECREASE OF CERTAIN 

 SPECIES OF BIRDS IN THE TAY AREA. 1 



By Col. JOHN CAMPBELL, M.B.O.U. 



THE distribution of birds, and the influences which affect 

 their increase or decrease in different parts of the country, 

 have always had a special interest for ornithologists. 



Although climatic conditions, and consequent scarcity 

 or abundance of food, play an important part in those 

 changes, more especially when we inquire into the decrease 

 of certain species, it is difficult to account for the appearance 

 of birds in districts where they had been previously unknown, 

 and for their settling down in those districts and making 

 them their permanent home. 



The question is whence they came, and what induced 

 them to come ? Numerous theories have been propounded 

 to account for this phenomenon, which I myself shall not 

 attempt to elucidate further than by suggesting that over- 

 population may have driven these birds from the districts 

 where they were bred, and caused them to seek new ground 

 where food was more abundant and the conditions of climate 

 and surroundings as favourable as the districts from which 

 they came. Any how, it is a case of fy sm's, fy reste at 

 least, let us hope so. Apart from the question of natural 

 conditions, however, comes that of protection as a means of 

 increasing our bird population, and persecution as a means 

 of diminishing it. 



With regard to the increase of birds, in the following 

 paper I propose to give five typical examples of certain 

 birds breeding in the Perthshire district birds which 

 twenty years ago had either not been recorded, or, if 

 recorded, only as occasionally breeding or as winter visitors. 



L We would be glad to see such subjects taken up and amplified for every 

 Natural Area in Scotland. EDITORS. 



