NUMBER XXIII 

 HOMING OF SEA-SWALLOWS 



HOMING pigeons have been used by man for 

 more than two thousand years, and we know 

 that after some training they are usually successful 

 in returning from great distances to their cots. 

 But we do not understand how they manage to do 

 this. Still less can we explain the fact that a 

 swallow may return from its wintering in Africa to 

 the Scottish farmstead where it was born the 

 year before. 



Some very interesting experiments on the homing 

 of sooty and noddy terns (or sea-swallows) have 

 been recently made by Professor J. B. Watson and 

 Dr. K. S. Lashley. They worked at Bird Key, one 

 of the islands of the Tortugas group at the mouth 

 of the Gulf of Mexico, where the terns nest in tens 

 of thousands. It is the most northerly part of the 

 terns' migrating range. 



The experiments are as follows : A bold, vigorous 

 tern is caught, it is marked with oil-paint on the 

 head and neck ; two tags (small and large, but 

 otherwise duplicate) are prepared, recording the 

 date, the place, and the kind of marking ; the small 

 tag is tied round the bird's neck ; the large tag is 



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