88 BIRD LIFE THROUGHOUT THE YEAR 



ing bleak ranges of hills, as shown by the fact that 

 those which land in South Devon diverge to either side 

 to avoid having to cross Dartmoor. It may seem 

 that inherited instinct has done enough in guiding the 

 migrants back to English shores, but she has still a 

 more wonderful task, that of enabling each bird to 

 find its way to its native district, in many cases to the 

 very spot where it was reared or which it frequented 

 the previous year. This seems to the writer the real 

 and inner mystery of migration. That birds are not 

 guided merely by the experience of their elders is 

 conclusively proved by the case of the cuckoo, where 

 the young birds of the year remain with us long after 

 the adult cuckoos have left. 



Who that sees the Swallows at the moment of arrival 

 make straight for the shed where they nested last year, 

 or the House Martin fly direct to the eaves, can doubt 

 that they are the identical birds whose departure he 

 watched in the autumn ? A pair of Wood Wrens 

 nested year after year within a yard of the same spot. 

 Over hundreds of leagues of land and sea the memory 

 of that shady bank deep in blue bells drew them with 

 the magnetic influence of home. Birds of the previous 

 year making for the spot where they were reared 

 and finding this occupied, or being perhaps driven 

 off by their elders, seek homes of their own. This 

 tends to a general dispersal, and, where the species is 

 increasing in numbers, to an extension of range into 



