98 THE MIGRATION OF BRITISH BIRDS 



size of that Refuge Area (II.)> and consequently fewer 

 number of individuals, would not demand such a wide 

 extension of northern range in Post-Glacial times, as 

 amongst the much more numerous individuals that 

 occupied the eastern Refuge (III.)- It is even possible 

 that the Glacial Epoch did not affect the individuals 

 of these species in Refuge Area II. at all. 



The White Stork [Ciconia alba), for instance, breeds 

 commonly in Iberia and North-west Africa. It also 

 breeds in Holland, Germany, and South Sweden, but 

 misses the British Islands. Why .'' There can be little 

 doubt that the birds breeding in Iberia were never 

 affected by the Glacial Epoch, but the birds breeding in 

 Holland, Germany, and Sweden undoubtedly were, and 

 were all exterminated, especially through their inability 

 to rear offspring. A portion of the species, however, 

 occupied Refuge Area III., and from those Storks 

 that peopled that area the individuals have descended 

 that breed in North-west Europe to-day, as is to my 

 mind surely indicated by the line of their migration at 

 the present time, namely, across France, Italy (where 

 they are not known to breed), and down the Danube 

 valley, across Turkey and Asia Minor. Significantly 

 enough, the Storks that migrate south-east from 

 northern areas winter the furthest south in Africa, pene- 

 trating down the Nile valley to the Cape ; whereas 

 those breeding in North-west Africa and Iberia — a 

 much more southerly area — only appear to draw south 

 to West Africa, and in my opinion reach that locality 

 by coasting round the Sahara east, south, and west 

 again, as they did when that area was a sea : as is usual 

 in such cases, the White Stork is only an abnormal 



