PULL OF THE NORTH 301 



but that as time progresses the pull increases in power 

 and brings them back to the right line. 



The power of this pull was observable in all the late 

 migrants during these rushes, which often came a 

 month after the usual time of the ending of migration, 

 and it was easiest to observe in plover and shore birds. 



When, out on horseback in the morning in late 

 March or in April, I encountered flocks of these belated 

 travellers — plover, curlew and sandpiper — I often tried 

 to force them to fly south. They appeared tired as if 

 they had been travelling all night, and were hungry 

 and seeking food in the short dew-wet grass, but 

 always with their heads to the north. Not a bird 

 would be seen to turn aside in any other direction. 

 Riding to the north side of the flock, I would suddenly 

 wheel round and charge at it, and up they would 

 spring, almost vertically, and fly over my head to a 

 distance of forty or fifty yards, then drop down and 

 go on looking for something to eat, still walking north. 



One can but infer that the attraction, the impelling 

 force — the "pull of the north," as I have called it — 

 increases until in the belated travellers it is an actual 

 physical pain, a pain and a sense of extreme fear, 

 which is intensified if the bird attempts to fly south. 



Then as to the perturbations or aberrations in 

 migration also manifested in the migrant previous to 

 departure — the irregularities which suggest that the 

 cause of migration, the force behind the impulse, is 

 itself subject to permutations and aberrations, which 

 affect the nervous system of the migrants. On this 

 subject, together with the one just discussed, the 



