NATURAL HISTORY, 153 



ing numbers in this district. The only way in which I can account 

 for these birds being winter visitors here, instead of summer mi- 

 grants as they are in the more northern counties, is that the 

 southern limit of their northern summer residence is above the 

 line of the most southern parts of the British Isles ; whilst the 

 northern limit of their southern retreat is the lower latitude of 

 our southern coasts. 



