THE GLACIAL RANGE CONTRACTION, ETC. 97 



we can then understand why it is that species breeding 

 commonly in Holland, Belgium, Germany, and even in 

 some instances Scandinavia and North-central Russia, 

 do not inhabit our area. Of the three British species 

 that regularly migrate south-east in autumn {conf. p. 84) 

 it is a most significant fact that they are common in 

 France (directly south of the British Isles) or Central 

 Europe, either as summer visitors or passing migrants, 

 yet are rare or abnormal in Iberia. Of the various 

 abnormal visitors to Britain, whose range in West 

 Europe does not reach as high as the British Isles, no 

 less than eight breed to the north of some part of our 

 area east say of Ostend, and where the North Sea is 

 150 miles or more across ; whilst others that breed a 

 long way south of us in the west approach us much 

 more closely in latitude in the east. Now all this 

 appears to suggest that the species breeding so close 

 and yet not visiting us are descended from the emigrants 

 that re-peopled Europe after the glaciers retreated from 

 Refuge Areas east say of E. long. 8^ spread slightly 

 to the west of that longitude in the north in one or two 

 instances, and in many instances attaining a higher 

 latitude than our own in districts directly north of that 

 Refuge Area — and present winter home. The individuals 

 of these species breeding in Iberia or North-west Africa 

 probably never ranged as high as our area in Pre-Glacial 

 times ; if they did, the Ice Age exterminated them, or 

 they were entirely absent from Western Europe, which 

 then extended down to the Canary Islands. Or did 

 they inhabit that area, we may presume that they were 

 sedentary as they are to-day, in the sense of not leaving 

 it in summer or winter ; or, yet again, the much smaller 



H 



